2025/05/12

Spring Boot 3 Data 2

Spring Data JPA

JPA: Java Persistence API,提供 POJO 物件持久化的標準規格,可把 Java 物件直接映射到資料庫中

JPA 是規格,Hibermate, TopLink, OpenJPA 都是 JPA 的實作。目前以 Hibernate 為 Java 最流行的 JPA framework。

Spring Data JPA 底層也是使用 Hibernate,最後透過 JDBC 連接資料庫。

spring-boot-starter-data-jpa 自動設定了 JPA,自動設定類別是

  • JpaRepositoriesAutoConfiguration

  • HibernateJpaAutoConfiguration

pom.xml

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
        </dependency>

        <dependency>
            <groupId>org.hibernate.orm</groupId>
            <artifactId>hibernate-community-dialects</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

application.yml

spring:
  application:
    name: data2

  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost/testweb
    username: root
    password: password

  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true
    properties:
      hibernate:
        # dialect: org.hibernate.dialect.MySQLDialect
        dialect: org.hibernate.community.dialect.MySQLLegacyDialect

傳統的 JPA 必需要設定 persistence.xml,但在 spring boot 不需要。

Entity class 只需要有 @Entity@SpringBootApplication 或是 @EnableAutoConfiguration 就會自動掃描所有 @Entity

Data2Application 直接啟動即可

@SpringBootApplication
public class Data2Application {

    public static void main(String[] args) {
        SpringApplication.run(Data2Application.class, args);
    }

}

UserController.java

package com.test.data2.controller;

import com.test.data2.entity.UserDO;
import com.test.data2.repo.UserRepository;
import lombok.RequiredArgsConstructor;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RequiredArgsConstructor
@RestController
public class UserController {

    private final UserRepository userRepository;

    @GetMapping("/user/info/{id}")
    public UserDO getUserInfo(@PathVariable("id") long id){
        UserDO userDO = userRepository.findById(id).orElseGet(null);
        return userDO;
    }

}

UserRepository.java

package com.test.data2.repo;

import com.test.data2.entity.UserDO;
import org.springframework.data.repository.CrudRepository;

public interface UserRepository extends CrudRepository<UserDO, Long> {

}

UserDO.java

package com.test.data2.entity;

import jakarta.persistence.*;
import lombok.Data;

import java.io.Serializable;
import java.util.Date;

@Data
@Entity(name = "user")
public class UserDO implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(nullable = false, unique = true)
    private String username;

    @Column(nullable = false)
    private String phone;

    @Column(name = "create_time", nullable = false)
    private Date createTime;

    @Column(nullable = false)
    private Integer status;

}

啟動後,可從網址 http://localhost:8080/user/info/2 取得 userid = 2 的資料

console 會出現 sql

Hibernate: select ud1_0.id,ud1_0.create_time,ud1_0.phone,ud1_0.status,ud1_0.username from user ud1_0 where ud1_0.id=?

note:

如果掃描不到,可加上 @EntityScan 指定 package/class

Spring data JPA 的 db operation 稱為 repository

  • org.springframework.data.repository.CrudRepository

  • org.springframework.data.repository.ListCrudRepository

  • org.springframework.data.repository.ListPagingRepository

  • org.springframework.data.repository.PagingAndSortingRepository

  • org.springframework.data.repository.kotlin.*

  • org.springframework.data.repository.reactive.*

UserRepository interface 會被自動掃描到,在 controller 能自動注入使用


MyBatis

MyBatis是一個Java持久化框架,它通過 XML 或 annotation 把物件與儲存程序或SQL語句關聯起來,對映成資料庫內對應的 record。

MyBatis-Plus 是 MyBatis 的封裝。


Redis

REmote DIctionary Server: Redis,是一種 key-value 的 NoSQL memory database。通常用在 cache 資料。

spring-boot-starter-data-redis

org.springframework.boot.autoconfigure.AutoConfiguration.imports 有註冊幾個自動設定類別

  • RedisAutoConfiguration

  • RedisReactiveAutoConfiguration

  • RedisRepositoriesAutoConfiguration

RedisAutoConfiguration 對應的參數綁定類別是 RedisProperties

在 application.yml 設定即可使用

spring:
  application:
    name: data3
  data:
    redis:
      host: localhost
      port: 6379
      database: 0
      password: password
#      client-type: jedis

RedisTemplate

有兩個預設的模板可直接使用

  • RedisTemplate

    可處理 <Object, Object>

  • StringRedisTemplate

    只能處理 <String, String> 的資料,預設使用 JDK 的 serializer

因為 StringRedisTemplate 繼承自 RedisTemplate,必須設定兩個 RedisTemplate,所以要搭配 @ConditionalOnSingleCandidate 注入

RedisTemplate 提供的 interface:

interface desc
GeoOperations 地理空間
HashOperations Hash data
HyperLogLogOperations HyperLogLog
ListOperations List
SetOperations Set
ValueOperations String
ZSetOperations Ordered Set

設定 pom.xml,要加上 spring-boot-starter-integration, spring-integration-redis

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-integration</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.integration</groupId>
            <artifactId>spring-integration-redis</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

要新增一個連線,注入 StringRedisTemplate 使用

package com.test.data3;

import lombok.RequiredArgsConstructor;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ValueOperations;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RequiredArgsConstructor
@RestController
public class RedisController2 {

    private final StringRedisTemplate stringRedisTemplate;

    @RequestMapping("/redis2/set")
    public String set(@RequestParam("name") String name, @RequestParam("value") String value) {
        ValueOperations<String, String> valueOperations = stringRedisTemplate.opsForValue();
        valueOperations.set(name, value);
        return valueOperations.get(name);
    }

}

呼叫網址 http://localhost:8080/redis2/set?name=test&value=12345 ,就會設定一個 redis key,可使用 redis-cli 檢查

> redis-cli -a password
127.0.0.1:6379> keys *
1) "test"
127.0.0.1:6379> get test
"12345"

也可以直接注入對應的 RedisTemplate 使用 valueOperations

@RequiredArgsConstructor
@RestController
public class RedisController3 {

//    private final StringRedisTemplate stringRedisTemplate;

    @Resource(name = "stringRedisTemplate")
    private ValueOperations<String, String> valueOperations;

    @RequestMapping("/redis3/set")
    public String set(@RequestParam("name") String name, @RequestParam("value") String value) {
        valueOperations.set(name, value);
        return valueOperations.get(name);
    }

}

自訂 RedisTemplate

@Configuration
public class RedisConfig {

    @Bean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {
        RedisTemplate<String, Object> template = new RedisTemplate<>();
        template.setConnectionFactory(factory);

        StringRedisSerializer stringSerializer = new StringRedisSerializer();
        RedisSerializer jacksonSerializer = getJacksonSerializer();

        template.setKeySerializer(stringSerializer);
        template.setValueSerializer(jacksonSerializer);
        template.setHashKeySerializer(stringSerializer);
        template.setHashValueSerializer(jacksonSerializer);
        template.setEnableTransactionSupport(true);
        template.afterPropertiesSet();

        return template;
    }

    private RedisSerializer getJacksonSerializer() {
        ObjectMapper om = new ObjectMapper();
        om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        om.activateDefaultTyping(LaissezFaireSubTypeValidator.instance,
                ObjectMapper.DefaultTyping.NON_FINAL);
        return new GenericJackson2JsonRedisSerializer(om);
    }
}

這裡 key 使用了 StringRedisSerializer, value 使用了 GenericJackson2JsonRedisSerializer

以下是幾個常用的 serializer

serializer desc
StringRedisSerializer String/byte[] 轉換器
JdkSerializationRedisSerializer JDK serializer
OxmSerializer XML serializer
Jackson2JsonRedisSerializer JSON serializer, 需要定義 JavaType
GenericJackson2JsonRedisSerializer JSON serializer, 不需要定義 JavaType

MongoDB

springboot 提供兩種 starter

  • spring-boot-starter-data-mongodb

  • spring-boot-starter-data-mongodb-reactive

首先修改 pom.xml

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-mongodb</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
        </dependency>

在 org.springframework.boot.autoconfigure.AutoConfiguration.imports 註冊了幾個自動設定類別

  • MongoDataAutoConfiguration

  • MongoReactiveDataAutoConfiguration

  • MongoRepositoriesAutoConfiguration

  • MongoAutoConfiguration

  • MongoReactiveAutoConfiguration

設定 application.yml

spring:
  data:
    mongodb:
      uri: mongodb://localhost:27017/test

使用 mongoTemplate

@RequiredArgsConstructor
@RestController
public class MongoController {

    public static final String COLLECTION_NAME = "test";
    private final MongoTemplate mongoTemplate;

    @RequestMapping("/mongo/insert")
    public User insert(@RequestParam("name") String name, @RequestParam("sex") int sex) {
        // add
        User user = new User(RandomUtils.nextInt(), name, sex);
        mongoTemplate.insert(user, COLLECTION_NAME);

        // query
        Query query = new Query(Criteria.where("name").is(name));
        return mongoTemplate.findOne(query, User.class, COLLECTION_NAME);
    }
}

新增 User.java

package com.test.data4;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.springframework.data.mongodb.core.mapping.Document;

@NoArgsConstructor
@AllArgsConstructor
@Data
@Document(collection = "test")
public class User {
    private long id;
    private String name;
    private int sex;

}

發送網址 http://localhost:8080/mongo/insert?name=test&sex=1

就會 insert 一筆資料到 mongodb collection: test

/* 1 */
{
    "_id" : NumberLong(708252679),
    "name" : "test",
    "sex" : 1,
    "_class" : "com.test.data4.User"
}

MongoRepository

新增 UserRepository

package com.test.data4;

import org.springframework.data.mongodb.repository.MongoRepository;

import java.util.List;

public interface UserRepository extends MongoRepository<User, Long> {

    List<User> findByName(String name);

}

修改 MongoController.java

    private final UserRepository userRepository;

    @RequestMapping("/mongo/insert2")
    public User repoInsert(@RequestParam("name") String name, @RequestParam("sex") int sex) {
        // add
        User user = new User(RandomUtils.nextInt(), name, sex);
        userRepository.save(user);

        // query
        return userRepository.findByName(name).get(0);
    }

發送網址 http://localhost:8080/mongo/insert2?name=test2&sex=1

就會新增 test2


Elasticsearch

springboot 支援3種客戶端

  • Elasticsearch 官方 REST 客戶端

  • Elasticsearch 官方 Java API Client

  • spring data elasticsearch 提供的 ReactiveElasticsearchClient

pom.xml

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
        </dependency>

在 org.spingframework.boot.autoconfigure.AutoConfiguration.imports 註冊了

  • ElasticsearchDataAutoConfiguration

  • ElasticsearchRepositoriesAutoConfiguration

  • ReactiveElasticsearchRepositoriesAutoConfiguration

  • ElasticsearchClientAutoConfiguration

  • ElasticsearchRestClientAutoConfiguration

  • ReactiveElasticsearchClientAutoConfiguration

參數綁定 ElasticsearchProperties

參數 spring.elasticsearch.*

application.yml

spring:
  elasticsearch:
    uris: http://localhost:9200
    connection-timeout: 5s
    socket-timeout: 10s
    username: elastic
    password: password

這邊是用關閉 xpack,使用 http 的方式連線

改用 https 可參考

ref: spring-boot-starter-data-elasticsearch es带x-pack后台配置 - 微信公众号-醉鱼Java - 博客园


使用 ElasticsearchTemplate

EsController.java

import lombok.RequiredArgsConstructor;
import org.apache.commons.lang3.RandomUtils;
import org.springframework.data.elasticsearch.client.elc.ElasticsearchTemplate;
import org.springframework.data.elasticsearch.core.mapping.IndexCoordinates;
import org.springframework.data.elasticsearch.core.query.Criteria;
import org.springframework.data.elasticsearch.core.query.CriteriaQuery;
import org.springframework.data.elasticsearch.core.query.Query;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RequiredArgsConstructor
@RestController
public class EsController {

    public static final String INDEX_JAVA = "java";
    private final ElasticsearchTemplate elasticsearchTemplate;

    @RequestMapping("/es/insert")
    public User insert(@RequestParam("name") String name, @RequestParam("sex") int sex) throws InterruptedException {
        // add
        User user = new User(RandomUtils.nextInt(), name, sex);
        IndexCoordinates indexCoordinates =  IndexCoordinates.of(INDEX_JAVA);
        User save = elasticsearchTemplate.save(user, indexCoordinates);

        // delay and query
        Thread.sleep(1000l);
        Query query = new CriteriaQuery(Criteria.where("name").is(name));
        return elasticsearchTemplate.searchOne(query, User.class, indexCoordinates).getContent();
    }
}

User.java

@NoArgsConstructor
@AllArgsConstructor
@Data
@Document(indexName = "java")
public class User {
    private long id;
    private String name;
    private int sex;

}

使用 UserRepository

修改 EsController.java

    private final UserRepository userRepository;
    @RequestMapping("/es/repo/insert")
    public User repoInsert(@RequestParam("name") String name, @RequestParam("sex") int sex) {
        // add
        User user = new User(RandomUtils.nextInt(), name, sex);
        userRepository.save(user);

        // query
        return userRepository.findByName(name).get(0);
    }

UserRepository.java

import org.springframework.data.elasticsearch.repository.ElasticsearchRepository;

import java.util.List;

public interface UserRepository extends ElasticsearchRepository<User, Long> {

    List<User> findByName(String name);

}

程式跟 MongoDB 類似

2025/05/05

Spring Boot 3 Data 1

spring boot 支援資料庫、connection pool、transaction 自動設定。資料庫還支援 H2, HSQL, Derby 嵌入式資料庫。NoSQL 支援 Mongodb, Neo4j, Elasticsearch, Redis, GemFire or Geode, Cassandra, Couchbase, LDAP, InfluxDB。比較常用的是 Redis, MongoDB, Elasticsearch。


嵌入式資料庫

存放在記憶體的資料庫

不需要設定 URL,只要引用 library 即可

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>org.hsqldb</groupId>
            <artifactId>hsqldb</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

資料來源 DataSource

java 是透過 javax.sql.DataSource 連接關聯式資料庫。spring boot 只需要引用 spring-boot-starter-data-jdbc 即可,另外還需要該關聯式資料庫的 JDBC driver,例如 MySQL 要用 mysql-connector

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jdbc</artifactId>
        </dependency>

        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
        </dependency>

spring-boot-starter-data-jdbc 包含預設的 HikariCP connection pool

DataSource 自動設定的類別是 DataSourceAutoConfiguration

自動配置檔案 org.springframework.boot.autoconfigure.AutoConfiguration.imports

因為資料庫自動設定類別使用 @ConditionalOnClass,如果 classpath 裡面有以下兩個類別,就會自動完成設定

  • DataSource.class

  • EmbeddedDatabaseType.class

會先設定外部關聯式資料庫 DataSource,再設定嵌入式資料庫。如果沒有自動設定的類別,就會使用 connection pool 的預設設定值

application.yml 的設定參數為 spring.datasource.*

spring:
  application:
    name: data1

  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    #driver-class-name: org.mariadb.jdbc.Driver
    url: jdbc:mariadb://localhost/testweb
    username: root
    password: password

也可以使用 MariaDB 的 driver

        <dependency>
            <groupId>org.mariadb.jdbc</groupId>
            <artifactId>mariadb-java-client</artifactId>
        </dependency>

driver-class 也要同時修改

    driver-class-name: org.mariadb.jdbc.Driver

因 Dialect 在 MySQL 版本有差異,啟動 application 會出現這樣的錯誤資訊

org.hibernate.dialect.Dialect            : HHH000511: The 5.5.68 version for [org.hibernate.dialect.MySQLDialect] is no longer supported, hence certain features may not work properly. The minimum supported version is 8.0.0. Check the community dialects project for available legacy versions.

這時候要調整使用的 Dialect

        <dependency>
            <groupId>org.hibernate.orm</groupId>
            <artifactId>hibernate-community-dialects</artifactId>
        </dependency>

application.yml

spring:
  jpa:
    properties:
      hibernate:
        # dialect: org.hibernate.dialect.MySQLDialect
        dialect: org.hibernate.community.dialect.MySQLLegacyDialect

啟動時,同時會看到 Hikari connection pool 的 log

HikariPool-1 - Starting...
HikariPool-1 - Added connection org.mariadb.jdbc.Connection@3a175162
HikariPool-1 - Start completed.

自訂 DataSource

直接註冊一個實作 DataSource 的 bean 即可

package com.test.data1;

import org.mariadb.jdbc.MariaDbDataSource;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;

@Configuration(proxyBeanMethods = false)
public class DbConfig {
    @Bean
    @ConfigurationProperties(prefix="spring.datasource")
    public DataSource dataSource() {
        return new MariaDbDataSource();
    }

}

也可定義兩個 DataSource,但第一個要設定為 @Primary

package com.test.data1;

import org.mariadb.jdbc.MariaDbDataSource;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;

import javax.sql.DataSource;

@Configuration(proxyBeanMethods = false)
public class DbConfig2 {

    @Primary
    @Bean
    @ConfigurationProperties(prefix="spring.datasource.xx.one")
    public DataSource dataSource1() {
        return new MariaDbDataSource();
    }

    @Bean
    @ConfigurationProperties(prefix="spring.datasource.xx.two")
    public DataSource dataSource2() {
        return new MariaDbDataSource();
    }
}

透過 AbstractRoutingDataSource#determineCurrentLookupKey 決定哪一個 data source。


Connection Pool

spring boot 預設使用 HikariCP

自動設定類別是 PooledDataSourceConfiguration

spring 提供以下幾種 connection pool,依照 libary dependency 判斷順序選擇

  • HikariCP

  • Tomcat

  • DBCP2

  • Oracle UCP

如果都沒有,就直接使用JDBC connection

可設定 spring.datasource.type ,這樣就不會自動選擇 connection pool

spring:
  datasource:
    type: org.apache.commons.dbcp2.BasicDataSource

資料庫初始化

spring boot 可在啟動時處理 DDL, DML

目前是用 SqlInitializationAutoConfiguration 自動設定

對應參數綁定是 SqlInitializationProperties,可透過 spring.sql.init.* 參數設定

spring:
  application:
    name: data1

  datasource:
    #driver-class-name: com.mysql.cj.jdbc.Driver
    driver-class-name: org.mariadb.jdbc.Driver
    url: jdbc:mariadb://localhost/testweb
    username: root
    password: password
  sql:
    init:
      mode: ALWAYS
      continue-on-error: true
      schema-locations: sql/create_user.sql
      data-locations:
        - classpath:sql/insert_user.sql

mode: 資料庫初始化模式

  • ALWAYS: 會對外部關聯式資料庫初始化,application 每一次啟動,該 sql 都會被執行一次

  • EMBEDDED: 只會對 embedded database 自動初始化

  • NEVER

continue-on-error: true,初始化錯誤,要不要繼續執行。如果 mode 為 ALWAYS,就會忽略重複 insert 有 primary key 的資料的錯誤

schema-locations: DDL script

data-locations: DML script


JdbcTemplate

JdbcTemplate 是 spring 用來簡化 JDBC operation 的 wrapper,只需要引用 spring-boot-starter-data-jdbc 就可以使用

自動設定類別是 JdbcTemplateAutoConfiguration,裡面使用了 JdbcTempateConfiguration,有預設的 JdbcTemplate instance,在 application 中注入即可使用

@Slf4j
@RequiredArgsConstructor
@SpringBootApplication
public class Data1Application {
    public final JdbcTemplate jdbcTemplate;

    public static void main(String[] args) {
        SpringApplication.run(Data1Application.class, args);
    }

    @Bean
    @Transactional
    public CommandLineRunner commandLineRunner() {
        return testJdbcTemplate();
    }

    private CommandLineRunner testJdbcTemplate() {
        return (args) -> {
            log.info("testing JdbcTemplate...");
            String username = jdbcTemplate.queryForObject("select username from user where id = 1", String.class);
            log.info("id = 1, username = {}", username);
        };
    }

}

自訂 JdbcTemplate

可以在 spring.jdbc.template.* 修改 jdbcTemplate 的設定

spring:
  jdbc:
    template:
      max-rows: 3
    private CommandLineRunner testJdbcTemplate2() {
        return (args) -> {
            log.info("testing JdbcTemplate2...");
            List<Map<String, Object>> result= jdbcTemplate.queryForList("select username from user");
            log.info("result list size={}", result.size());
        };
    }

因為設定的限制,回傳的 list size 最多只會是 3


transaction

spring-boot-starter-data-jdbc 會引用 transaction 相關 library,自動設定類別有

  • TransactionAutoConfiguration

  • DataSourceTransactionManagerAutoConfiguration

參數綁定類別是 TransactionProperties

spring.transaction.* 參數設定

新增一個 user DTO 物件

package com.test.data1.entity;

import lombok.Data;
import org.springframework.data.relational.core.mapping.Column;

import java.time.LocalDateTime;

@Data
public class UserDO {

    private long id;

    private String username;

    private String phone;

    @Column(value = "create_time")
    private LocalDateTime createTime;

    private int status;

}

製作 DAO interface UserDao.java

package com.test.data1.dao;

public interface UserDao {
    void update();
}

UserDaoImpl.java

package com.test.data1.dao.impl;

import com.test.data1.dao.UserDao;
import lombok.RequiredArgsConstructor;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

@RequiredArgsConstructor
@Service
public class UserDaoImpl implements UserDao {

    public final JdbcTemplate jdbcTemplate;

    @Transactional
    @Override
    public void update() {
        jdbcTemplate.execute("update user set username = 'Petty' where id = 1");
        jdbcTemplate.execute("update user set username = 'Yoga' where id = 2");
        throw new RuntimeException("test exception");
    }

}

Data1Application.java

@Slf4j
@RequiredArgsConstructor
@SpringBootApplication
public class Data1Application {
    public final JdbcTemplate jdbcTemplate;

    public final UserDao userDao;

    public static void main(String[] args) {
        SpringApplication.run(Data1Application.class, args);
    }

    @Bean
    @Transactional
    public CommandLineRunner commandLineRunner() {
        return useJdbcTemplate();
    }

    private CommandLineRunner useJdbcTemplate() {
        return (args) -> {
            log.info("using JdbcTemplate...");
            BeanPropertyRowMapper<UserDO> rowMapper = new BeanPropertyRowMapper<>(UserDO.class);
            UserDO userDO = jdbcTemplate.queryForObject("select * from user where id = 2", rowMapper);
            log.info("user info : {}", userDO);

            List<UserDO> userDOList = jdbcTemplate.query("select * from user", rowMapper);
            log.info("user list: {}", userDOList);

            log.info("userDao.update()...");
            userDao.update();

            List<UserDO> userDOList2 = jdbcTemplate.query("select * from user", rowMapper);
            log.info("user list2: {}", userDOList2);
        };
    }
}

雖然在 update() 裡面修改了 username,但因爲 @Transactional 的關係,資料 rollback 回原本的狀態,修改的資料會被 rollback。


transaction 失敗的原因

  1. Database 不支援 transaction。MySQL 的 MyISAM 不支援 transaction,在 5.5 以後預設是使用 InnoDB,這個才有支援 transaction

  2. 沒有被 spring 管理

    UserDaoImpl 裡面的 @Service 如果刪除,就不會受到 spring 管理

    //@Service
    public class UserDaoImpl implements UserDao {
    }
  3. @Transactional 的 method 必須要是 public method

    如果要用在非 public method,必須開啟 AspectJ framework 的靜態代理模式

  4. 呼叫內部 method

    business method 一定要經過 spring 才能處理 transaction

    以下這兩種狀況,transaction 都不會生效

    @Service
    public class UserDaoImpl implements UserDao {
       public void update1(User user) {
           //call update2
           update2(user);
       }
    
       @Transactional
       public void update2(User user) {
           //update user
       }
    }
    @Service
    public class UserDaoImpl implements UserDao {
       @Transactional
       public void update1(User user) {
           //call update2
           update2(user);
       }
    
       @Transactional(propagation = Propagation.REQUIRES_NEW)
       public void update2(User user) {
           //update user
       }
    }

    解決方法是在 UserDaoImpl 裡面注入自己,用該物件,呼叫另一個 method

    @EnableAspectJAutoProxy(exposeProxy = true)

    取得當前的 proxy,並呼叫 method

    ((UserDaoImpl)AopContext.currentProxy()).update2();
  5. 沒有配置 transaction manager

    必須要有 PlatformTransactionManager 才能處理 transaction

    @Bean
    public PlatformTransactionManager transactionManager(DataSource dataSource) {
       return new DataSourceTransactionalManager(dataSource);
    }

    spring-boot-starter-data-jdbc 裡面自動設定了一個 DataSourceTransactionalManager,所以可直接使用

  6. 設定不支援 transaction

    @Service
    public class UserDaoImpl implements UserDao {
       @Transactional
       public void update1(User user) {
           //call update2
           update2(user);
       }
    
       @Transactional(propagation = Propagation.NOT_SUPPORTED)
       public void update2(User user) {
           //update user
       }
    }
  7. 沒有 throw exception,就不會 rollback

    @Service
    public class UserDaoImpl implements UserDao {
       @Transactional
       public void update1(User user) {
           try{
           } catch(Exception e) {
           }
       }
    }
  8. exception 類別不同

    因為 spring 預設針對 RuntimeException 進行 rollback,如果該 method throw 的 exception 類別錯誤,也不會觸發 rollback,除非在 @Transactional 設定 rollbackFor Exception 類別

    @Service
    public class UserDaoImpl implements UserDao {
       @Transactional(rollbackFor = Exception.class)
       public void update1(User user) {
           try{
           } catch(Exception e) {
              throw new Exception(e.getMessage());
           }
       }
    }

2025/04/21

SpringBoot3 Web 3

CORS 跨來源資源共享

SAMEORIGIN 同源政策,是 Netscape 提出,所有支援 Javascript 的瀏覽器都使用這個策略,同源是 domain name, port, protocol 相同的意思,網頁執行一個 script 時,會檢查是否同源,非同源就會拒絕。

只要 domain name, port, protocol 某一個不同,就代表 cross origin。

CORS 允許伺服器指示瀏覽器允許從除其自身以外的任何來源載入資源。

spring MVC 本身透過在 method 上設定 @CrossOrigin

@Slf4j
@RestController
@Validated
public class ResponseBodyController {

    @CrossOrigin
    @GetMapping(value = "/user/json/{userId}", produces = MediaType.APPLICATION_JSON_VALUE)
    public User getJsonUserInfo(@PathVariable("userId") @Size(min = 5, max = 8) String userId) {
        User user = new User("test1", 18);
        user.setId(Long.valueOf(userId));
        log.info("user info: {}", user);
        return user;
    }
}

@CrossOrigin 預設支援所有 request 來源、所有 http header, methods

@CrossOrigin 也可以用在 class

@Slf4j
@CrossOrigin(origins = "https://www.test.com", maxAge=3600)
@RestController
public class ResponseBodyController {
}

也可以放在 WebMvcConfigurer

@Configuration
@RequiredArgsConstructor
public class WebConfig implements WebMvcConfigurer {

    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/user/**")
                .allowedMethods("GET", "POST")
                .allowedOrigins("https://www.test.com")
                .allowCredentials(true)
                .maxAge(3600);
    }
}

安全性

加上 security library

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
        </dependency>

啟動時會出現以下的 log

2024-11-20T16:36:50.740+08:00  WARN 5307 --- [           main] .s.s.UserDetailsServiceAutoConfiguration : 

Using generated security password: 06ee988c-9983-4187-b040-5bfadde83893

This generated password is for development use only. Your security configuration must be updated before running your application in production.

2024-11-20T16:36:50.784+08:00  INFO 5307 --- [           main] r$InitializeUserDetailsManagerConfigurer : Global AuthenticationManager configured with UserDetailsService bean with name inMemoryUserDetailsManager

瀏覽 http://localhost:8080/demo1/test 時,會出現 ## Please sign in 的登入畫面

這時候填寫

username: user
password: 06ee988c-9983-4187-b040-5bfadde83893

就可以打開 index 頁面

可在 application.yml 修改預設的帳號密碼

spring:
  security:
    user:
      name: root
      password: password

自訂安全機制

可註冊 SecurityFilterChain 與 UserDetailsService 類別,實作自訂安全機制

SecurityConfig.java

package tw.com.test.demo1.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.core.userdetails.User;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.provisioning.InMemoryUserDetailsManager;
import org.springframework.security.web.SecurityFilterChain;

import static org.springframework.security.config.Customizer.withDefaults;

@Configuration
public class SecurityConfig {

    @Bean
    public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
        return http.authorizeHttpRequests((authorize) -> {
            authorize.requestMatchers("/test/**").hasRole("TEST").requestMatchers("/**").permitAll();
        }).logout((logout) -> logout.logoutUrl("/")).formLogin(withDefaults()).build();
    }

    @Bean
    public UserDetailsService userDetailsService() {
        InMemoryUserDetailsManager manager = new InMemoryUserDetailsManager();
        manager.createUser(User.withUsername("test").password("{noop}test").roles("ADMIN", "TEST").build());
        manager.createUser(User.withUsername("root").password("{noop}root").roles("ADMIN").build());
        return manager;
    }

}

REST service

實作 REST service 有兩種方式

  • RestTemplate (servlet)

  • WebClient (reactive)

RestTemplate (servlet)

pom.xml

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

自動設定類別 RestTemplateAutoConfiguration

註冊在 org.springframework.boot.autoconfigure.AutoConfiguration.imports

ResTemplate 並沒有任何預設的註冊

必須要先註冊一個 RestTemplate instance,可透過 restTemplateBuilder 產生

@Configuration
@RequiredArgsConstructor
public class WebConfig implements WebMvcConfigurer {

    @Bean
    public RestTemplate defaultRestTemplate(RestTemplateBuilder restTemplateBuilder) {
        return restTemplateBuilder
                .build();
    }
}

新增一個 controller 測試

package tw.com.test.demo1.controller;

import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestClient;
import org.springframework.web.client.RestTemplate;
import tw.com.test.demo1.bean.User;

@Slf4j
@RestController
@RequiredArgsConstructor
public class CallRestController {

    public static final String GET_USERINFO_URL = "http://localhost:8080/demo1/user/json/{uid}";
    private final RestTemplate restTemplate;

    @GetMapping("/restTemplate/{uid}")
    public User restTemplate(@PathVariable("uid") String uid) {
        return this.restTemplate.getForObject(GET_USERINFO_URL, User.class, uid);
    }

}

用 postman 測試 GET http://localhost:8080/demo1/restTemplate/10000

回傳結果

{
    "id": 10000,
    "age": 18,
    "username": "test1"
}

自訂 RestTemplate,加上 timeout, basic authentication

    @Bean
    public RestTemplate defaultRestTemplate(RestTemplateBuilder restTemplateBuilder) {
        return restTemplateBuilder
                .setConnectTimeout(Duration.ofSeconds(5))
                .setReadTimeout(Duration.ofSeconds(5))
                .basicAuthentication("test", "test")
                .build();
    }

也可以直接實作 RestTemplateCustomizer

package tw.com.test.demo1.handler;

import lombok.extern.slf4j.Slf4j;
import org.apache.hc.client5.http.classic.HttpClient;
import org.apache.hc.client5.http.config.RequestConfig;
import org.apache.hc.client5.http.impl.classic.HttpClientBuilder;
import org.apache.hc.client5.http.impl.routing.DefaultProxyRoutePlanner;
import org.apache.hc.client5.http.routing.HttpRoutePlanner;
import org.apache.hc.core5.http.HttpException;
import org.apache.hc.core5.http.HttpHost;
import org.apache.hc.core5.http.protocol.HttpContext;
import org.springframework.boot.web.client.RestTemplateCustomizer;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.stereotype.Component;
import org.springframework.web.client.RestTemplate;


@Slf4j
@Component
public class CustomRestTemplateCustomizer implements RestTemplateCustomizer {

    @Override
    public void customize(RestTemplate restTemplate) {
        HttpRoutePlanner routePlanner = new CustomRoutePlanner(new HttpHost("proxy.test.com"));
        RequestConfig requestConfig = RequestConfig.custom().build();
        HttpClient httpClient = HttpClientBuilder.create().setDefaultRequestConfig(requestConfig).setRoutePlanner(routePlanner).build();
        restTemplate.setRequestFactory(new HttpComponentsClientHttpRequestFactory(httpClient));
    }

    static class CustomRoutePlanner extends DefaultProxyRoutePlanner {

        CustomRoutePlanner(HttpHost proxy) {
            super(proxy);
        }

        @Override
        protected HttpHost determineProxy(HttpHost target, HttpContext context) throws HttpException {
            log.info("hostName is {}", target.getHostName());
            if ("localhost".equals(target.getHostName())) {
                return null;
            }
            return super.determineProxy(target, context);
        }

    }

}

有用到 http client 5

        <dependency>
            <groupId>org.apache.httpcomponents.client5</groupId>
            <artifactId>httpclient5</artifactId>
        </dependency>

        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpcore</artifactId>
        </dependency>

也可以實作最底層的 HttpAccessor


WebClient (reactive)

WebClient 是使用 speign WebFlux 的 http client

pom.xml

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>io.projectreactor</groupId>
            <artifactId>reactor-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <scope>provided</scope>
        </dependency>
    </dependencies>

User.java

package tw.com.test.demo3.bean;

import lombok.AllArgsConstructor;
import lombok.Data;

@Data
@AllArgsConstructor
public class User {
    private Long id;
    private String username;
    private Integer age;
}

WebConfig.java

package tw.com.test.demo3.config;

import io.netty.channel.ChannelOption;
import io.netty.handler.timeout.ReadTimeoutHandler;
import io.netty.handler.timeout.WriteTimeoutHandler;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.reactive.ReactorClientHttpConnector;
import org.springframework.web.reactive.function.client.WebClient;
import reactor.netty.http.client.HttpClient;

@Configuration
public class WebConfig {

    @Bean
    public WebClient webClient(WebClient.Builder webClientBuilder) {
        return webClientBuilder.build();
    }

}

CallRestController.java

package tw.com.test.demo3.controller;

import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.reactive.function.client.WebClient;
import reactor.core.publisher.Mono;
import tw.com.test.demo3.bean.User;

@Slf4j
@RestController
@RequiredArgsConstructor
public class CallRestController {

    public static final String GET_USERINFO_URL = "http://localhost:8080/user/json/{uid}";

    private final WebClient webClient;

    @GetMapping("/webClient/{uid}")
    public Mono<User> webClient(@PathVariable("uid") String uid) {
        return this.webClient.get().uri(GET_USERINFO_URL, uid).retrieve().bodyToMono(User.class);
    }

}

這是要呼叫的 rest url

package tw.com.test.demo3.controller;

import lombok.extern.slf4j.Slf4j;
import org.springframework.http.MediaType;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.*;
import tw.com.test.demo3.bean.User;

@Slf4j
@RestController
@Validated
public class ResponseBodyController {

    @CrossOrigin
    @GetMapping(value = "/user/json/{userId}", produces = MediaType.APPLICATION_JSON_VALUE)
    public User getJsonUserInfo(@PathVariable("userId") String userId) {
        User user = new User((long)1000, "test", 18);
        user.setId(Long.valueOf(userId));
        log.info("user info: {}", user);
        return user;
    }

}

以 GET method 呼叫 http://localhost:8080/webClient/10000

就能取得結果

{
    "id": 10000,
    "username": "test",
    "age": 18
}

自訂 WebClient

修改 WebConfig.java,改用 reactor netty 的 ReactorClientHttpConnector

package tw.com.test.demo3.config;

import io.netty.channel.ChannelOption;
import io.netty.handler.timeout.ReadTimeoutHandler;
import io.netty.handler.timeout.WriteTimeoutHandler;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.reactive.ReactorClientHttpConnector;
import org.springframework.web.reactive.function.client.WebClient;
import reactor.netty.http.client.HttpClient;

@Configuration
public class WebConfig {

//    @Bean
//    public WebClient webClient(WebClient.Builder webClientBuilder) {
//        return webClientBuilder.build();
//    }

    @Bean
    public WebClient webClient(WebClient.Builder webClientBuilder) {
        HttpClient httpClient = HttpClient.create().option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 3).doOnConnected(conn -> {
            conn.addHandlerLast(new ReadTimeoutHandler(3000));
            conn.addHandlerLast(new WriteTimeoutHandler(3000));
        });
        ReactorClientHttpConnector connector = new ReactorClientHttpConnector(httpClient);
        return webClientBuilder.clientConnector(connector).build();
    }

}

可改用 ClientHttpConnector 的其他實作的客戶端,目前 spring boot 支援

  • Reactor netty (default)

  • Jetty RS Client

  • Apache HttpClient

  • JDK HttpClient

2025/04/14

SpringBoot3 Web 2

template engine

  • FreeMaker

  • Thymeleaf -> 目前最常使用

  • Mustache

要使用 Thymeleaf 必須加上套件

pom.xml

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

spring 會自動透過 ThymeleafAutoConfiguration 自動設定

設定參數是 spring.thymeleaf.*

預設目錄為 src/main/resources/templates

預設模板檔案是 .html

預設檔案編碼為 UTF-8

Demo1Application.java

@Slf4j
@SpringBootApplication
@Controller
@RequiredArgsConstructor
public class Demo1Application {
    private final HttpServletRequest request;

    public static void main(String[] args) {
        SpringApplication.run(Demo1Application.class);
    }

    @GetMapping(value = "/test/{content}")
    public String test(@PathVariable("content") String content) {
        request.setAttribute("content", content);
        return "test";
    }
}

templates/test.html

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="utf-8"/>
    <title>test</title>
    <link rel="stylesheet" type="text/css" th:href="@{/css/test.css}"/>
    <script th:src="@{/js/test.js}"></script>
</head>
<body>

<a id="content" th:utext="${content}" class="red" onclick="changeColor()"></a>

</body>
</html>

這樣就能瀏覽網頁 http://localhost:8080/demo1/test/content


異常處理

預設是映射到 /error 頁面,錯誤處理是 BasicErrorController (implements ErrorController)

自訂 global error

@ControllerAdvice@ExceptionHandler 製作 ErrorHandler

package tw.com.test.demo1.handler;

import jakarta.servlet.http.HttpServletRequest;
import lombok.extern.slf4j.Slf4j;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.validation.BindingResult;
import org.springframework.validation.FieldError;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;

@ControllerAdvice
@Slf4j
public class GlobalExceptionHandler {

    @ResponseBody
    @ExceptionHandler(value = {Exception.class})
    public ResponseEntity<?> handleException(HttpServletRequest request, Throwable ex) {
        log.error("global exception:", ex);
        return new ResponseEntity<>("global exception", HttpStatus.OK);
    }

    @ResponseBody
    @ExceptionHandler(value = {MethodArgumentNotValidException.class})
    public ResponseEntity handleMethodArgumentNotValidException(MethodArgumentNotValidException ex) {
        BindingResult bindingResult = ex.getBindingResult();
        StringBuilder sb = new StringBuilder("Parameter Error:");
        for (FieldError fieldError : bindingResult.getFieldErrors()) {
            sb.append(fieldError.getField()).append(":").append(fieldError.getDefaultMessage()).append(", ");
        }
        String msg = sb.toString();
        return new ResponseEntity(msg, HttpStatus.OK);
    }

}

自訂異常頁面

在任何一個靜態目錄,建立 /error 目錄,並建立 error code html page

  • main/resources/public/error/404.html

  • main/resources/public/error/500.html


參數驗證

spring boot 支援 JSR-303 spec,可針對介面參數進行驗證,例如常用的 hibernate-validator 就實作了 JSR-303

        <dependency>
            <groupId>org.hibernate.validator</groupId>
            <artifactId>hibernate-validator</artifactId>
        </dependency>

spring boot 不需要加上 hibernate-validator,只需要引用 spring-boot-starter-validation

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
        </dependency>

jakarta.validation-api-3.0.2.jar 裡面的 package: jakarta.validation.constraints,裡面有所有 constraints 的類別

  • AssertFalse, AssertTrue

  • DecimalMax, DecimalMin

  • Digits

  • Email

  • Future, FutureOrPresent

  • Max, Min

  • Negative, NegativeOrZero

  • NotBlank, NotEmpty, NotNull

  • Null

  • Past, PastOrPresent

  • Pattern

  • Positive, PositiveOrZero

  • Size

引用 spring-boot-starter-validation 後,就可使用 @Valid 或是 @Validated

@Valid 是 Jarkarta spec 的 annotation

@Validated 是 spring 支援的 JSR-303 annotation,功能比較強

常用做法是在 interface 類別 (ex: controller) 使用 @Validated ,約束註解放在 method 的參數,或是放在類別 member variable 上面

User.java

package tw.com.test.demo1.bean;

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import jakarta.validation.constraints.NotNull;
import jakarta.validation.constraints.Size;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
public class User {

    public User(String userName, Integer age) {
        this.userName = userName;
        this.age = age;
    }

    private Long id;

    @NotNull
    @JsonProperty(value = "username", required = true)
    @Size(min = 5, max = 10)
    private String userName;

    @NotNull
    private Integer age;

    @JsonIgnore
    private String address;

    @JsonInclude(JsonInclude.Include.NON_NULL)
    private String memo;

}

ResponseBodyController.java

package tw.com.test.demo1.controller;

import jakarta.validation.constraints.Size;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.RandomUtils;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.*;
import tw.com.test.demo1.bean.OrderInfo;
import tw.com.test.demo1.bean.User;
import tw.com.test.demo1.bean.UserXml;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

@Slf4j
@RestController
@Validated
public class ResponseBodyController {

    @CrossOrigin
    @GetMapping(value = "/user/json/{userId}", produces = MediaType.APPLICATION_JSON_VALUE)
    public User getJsonUserInfo(@PathVariable("userId") @Size(min = 5, max = 8) String userId) {
        User user = new User("test1", 18);
        user.setId(Long.valueOf(userId));
        log.info("user info: {}", user);
        return user;
    }

    @GetMapping(value = "/user/xml/{userId}", produces = MediaType.APPLICATION_XML_VALUE)
    public UserXml getXmlUserInfo(@PathVariable("userId") String userId) {
        UserXml user = new UserXml();
        user.setName("test1name");
        user.setId(userId);

        List<OrderInfo> orderList = new ArrayList<>();
        OrderInfo orderInfo1 = new OrderInfo("001", 11, new Date());
        OrderInfo orderInfo2 = new OrderInfo("002", 22, new Date());
        OrderInfo orderInfo3 = new OrderInfo("003", 33, new Date());
        orderList.add(orderInfo1);
        orderList.add(orderInfo2);
        orderList.add(orderInfo3);
        user.setOrderList(orderList);

        return user;
    }

    @PostMapping(value = "/user/save")
    public ResponseEntity saveUser(@RequestBody @Validated User user) {
        user.setId(RandomUtils.nextLong());
        return new ResponseEntity(user, HttpStatus.OK);
    }

    @GetMapping("/")
    public String index() {
        return "index page.";
    }

}

驗證異常時,會出現 MethodArgumentNotValidException,在 global error 裡面註冊這個 Exception 的 handler

package tw.com.test.demo1.handler;

import jakarta.servlet.http.HttpServletRequest;
import lombok.extern.slf4j.Slf4j;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.validation.BindingResult;
import org.springframework.validation.FieldError;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

@ControllerAdvice
@Slf4j
public class GlobalExceptionHandler {

    @ExceptionHandler(MethodArgumentNotValidException.class)
    public ResponseEntity<Map<String, String>> handleValidationErrors(MethodArgumentNotValidException ex) {
        List<FieldError> errorList =  ex.getBindingResult().getFieldErrors();
        Map<String, String> errorMap = errorList.stream()
                .collect(Collectors.toMap(
                        value -> value.getField(),
                        value -> value.getDefaultMessage()));
        return new ResponseEntity<>(errorMap, new HttpHeaders(), HttpStatus.BAD_REQUEST);
    }

}

測試 http://localhost:8080/demo1/user/save

{
    "username": "11",
    "age": 11
}

結果

{
    "userName": "大小必須在 5 和 10 之間"
}

i18n

spring 預設會在類別路徑的根目錄搜尋是否有多國語言資源

自動設定類別是 org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration

設定參數

spring:
  messages:
    # i18n 檔名,預設為 messages,可指定多個
    basename: i18n/common, i18n/index
    encoding: UTF-8
    # 找不到時,使用目前 OS 的語言,預設為 true
    # false 就是使用 messages.properties
    fallback-to-system-locale: false
    # cache 時間(s),不設定代表永久 cache
#    cache-duration: 60

搭配 Thymeleaf

pom.xml

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

resources/i18n/common.properties

brand=Java

resources/i18n/index.properties

index.hi=hello
index.welcome=welcome

resources/i18n/index_zh_TW.properties

index.hi=你好
index.welcome=歡迎光臨

resources/templates/index.html

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="utf-8"/>
    <title>index</title>
</head>
<body>

<label th:text="#{brand}"></label>
<label th:text="#{index.hi}"></label>
<label th:text="#{index.welcome}"></label>

</body>
</html>

ResponseBodyController.java

package tw.com.test.demo1.controller;

import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;

@Slf4j
@Controller
public class PageController {

    @GetMapping(value = "/")
    public String index() {
        return "index";
    }

}

瀏覽網頁 http://localhost:8080/demo1/

會根據 request header 產生頁面結果

Accept-Language: zh-TW,zh;q=0.9,en-US;q=0.8,en;q=0.7,zh-CN;q=0.6

response header

Content-Language: zh-TW
Content-Type: text/html;charset=UTF-8

切換 i18n

設定預設 locale,透過網址參數 url?lang=zh_TW 切換 locale

package tw.com.test.demo1.config;

import lombok.RequiredArgsConstructor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.LocaleResolver;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.i18n.LocaleChangeInterceptor;
import org.springframework.web.servlet.i18n.SessionLocaleResolver;

import java.util.Locale;

@Configuration
@RequiredArgsConstructor
public class WebConfig implements WebMvcConfigurer {

    // 設定預設的 locale 為 en
    @Bean
    public LocaleResolver localeResolver() {
        SessionLocaleResolver sessionLocaleResolver = new SessionLocaleResolver();
        sessionLocaleResolver.setDefaultLocale(Locale.US);
        return sessionLocaleResolver;
    }

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(localeChangeInterceptor());
    }

    /**
     * 切換語言攔截器,通過 url?lang=zh_TW 形式進行切換
     * @return
     */
    private LocaleChangeInterceptor localeChangeInterceptor() {
        LocaleChangeInterceptor localeChangeInterceptor = new LocaleChangeInterceptor();
        localeChangeInterceptor.setParamName("lang");
        return localeChangeInterceptor;
    }
}

瀏覽網址

http://localhost:8080/demo1/?lang=

http://localhost:8080/demo1/?lang=zh_TW


session cluster

spring session 可將 session store 存放到第三方儲存庫中,可支援存在

  • Redis

  • JDBC

  • Hazelcast

  • MongoDB

session 的自動設定類別是 org.springframework.boot.autoconfigure.session.SessionAutoConfiguration

自動設定檔 org.springframework.boot.autoconfigure.AutoConfiguration.imports

Session 的參數綁定類別是 SessionProperties

參數 spring.session.*

Redis 有自己的設定擴充參數 spring.session.redis.* ,設定類別 RedisSessionProperties


以下以 redis 為例

pom.xml

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.session</groupId>
            <artifactId>spring-session-data-redis</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>

        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <scope>provided</scope>
        </dependency>
    </dependencies>

application.yml

spring:
  session:
    timeout: 30m
  data:
    redis:
      host: localhost
      port: 6379
      password: password

WebConfig.java

package tw.com.test.demo2;

import lombok.RequiredArgsConstructor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
@RequiredArgsConstructor
public class WebConfig implements WebMvcConfigurer {

    private final LoginInterceptor loginInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(loginInterceptor).addPathPatterns("/**").excludePathPatterns("/login/**");
    }

}

建立測試 controller

IndexController.java

package tw.com.test.demo2;

import jakarta.servlet.http.HttpSession;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

@Slf4j
@RequiredArgsConstructor
@Controller
public class IndexController {

    private final HttpSession httpSession;

    @ResponseBody
    @RequestMapping("/login")
    public String login() {
        return "login page.";
    }

    @RequestMapping("/login/submit")
    public String loginSubmit(@RequestParam("username") String username) {
        if (StringUtils.isNotBlank(username)) {
            httpSession.setAttribute("username", username);
            return "/index";
        }
        return "/login";
    }

    @ResponseBody
    @RequestMapping("/index")
    public String index() {
        log.info("session id: {}", httpSession.getId());
        return "index page.";
    }

    @RequestMapping("/logout")
    public String logout() {
        httpSession.invalidate();
        return "/login";
    }

}

LoginInterceptor.java

package tw.com.test.demo2;

import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;
import lombok.RequiredArgsConstructor;
import org.apache.commons.lang3.StringUtils;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;

@Component
@RequiredArgsConstructor
public class LoginInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        HttpSession session = request.getSession();
        String username = (String) session.getAttribute("username");
        if (StringUtils.isBlank(username)) {
            response.sendRedirect("/login");
            return false;
        }
        return true;
    }

}

Demo2Application.java

package tw.com.test.demo2;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Demo2Application {

    public static void main(String[] args) {
        SpringApplication.run(Demo2Application.class, args);
    }

}

在 8080, 8081 啟動兩個 applications

java -jar application.jar --server.port=8080
java -jar application.jar --server.port=8081

還沒有登入時,瀏覽網址 http://localhost:8080/index 會轉到 http://localhost:8080/login

以這個網址登入

http://localhost:8080/login/submit?username=test

畫面是 index page

登入成功後,會有兩個 cookie: SESSIONID, SESSION

spring session 是使用 SESSION 跨 application instances

Cookie:
SESSIONID=snvMXo4CMMxNxnD9F/c98cBpqlXTmxpFoM+Mv7yYGCqw=; SESSION=NzVhMjM1ZWMtMDNiMy00ZGY3LWE5NjQtODgzMGQ0YWM4OTZl

到 redis 查詢

redis-cli -h localhost -p 6379 -a password
1) "spring:session:sessions:75a235ec-03b3-4df7-a964-8830d4ac896e"
localhost:6379> keys *
1) "spring:session:sessions:75a235ec-03b3-4df7-a964-8830d4ac896e"
localhost:6379> ttl "spring:session:sessions:75a235ec-03b3-4df7-a964-8830d4ac896e"
(integer) 1797

ttl 代表該 session id 的存活時間是 1797 秒,因為剛剛設定為 30 minutes

75a235ec-03b3-4df7-a964-8830d4ac896e 的 base64 encode 結果就是 NzVhMjM1ZWMtMDNiMy00ZGY3LWE5NjQtODgzMGQ0YWM4OTZl

如果呼叫 http://localhost:8081/logout ,會發現 8080, 8081 的網頁,都會變成需要 login 的狀態


2025/04/07

SpringBoot3 Web 1

有兩種 Web

  • servlet 傳統的 MVC

  • reactive (webflux)

傳統的 MVC 用的是同步式 blocking IO,webflux 是使用非同步 non-blocking IO。目前大部分都還是使用 servlet

spring-boot-starter-web 可啟動 servlet web service,WebMvcAutoConfiguration 是自動設定類別

  • 對 ContentNegotiatingViewResolver 及 BeanNameViewResolver 的 bean 註冊

  • 支援靜態資源,含靜態網頁及 webjars

  • 對 Converter, Generic Converter, Formatter 的 bean 自動註冊

  • 支援 HttpMessageConverter 消息轉換器

  • 支援 messageCodesResolver 自動註冊

  • 自動使用 ConfigurableWebBindingInitializer 的 bean

embedded container

預設使用 tomcat

name spring-boot
Tomcat spring-boot-starter-tomcat
Jetty spring-boot-starter-jetty
Undertow spring-boot-starter-undertow

設定

ref: Serve Static Resources with Spring | Baeldung

ref: Serving JSP with Spring Boot 3

可參考 ServerProperties (Spring Boot 3.3.5 API) 類別裡面的參數設定

tomcat 可透過 server.tomcat.* 設定

server:
  port: 8081
  servlet:
    context-path: /demo1

只要實作 WebServerFactoryCustomizer 就能自訂 servlet container

CustomTomcatWebServerFactoryCustomizer.java

package tw.com.test.demo1.config;

import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;
import org.springframework.boot.web.server.WebServerFactoryCustomizer;
import org.springframework.stereotype.Component;

import java.time.Duration;

@Component
public class CustomTomcatWebServerFactoryCustomizer implements WebServerFactoryCustomizer<TomcatServletWebServerFactory> {

    @Override
    public void customize(TomcatServletWebServerFactory server) {
        server.addConnectorCustomizers((connector) -> {
            connector.setPort(8088);
            connector.setAsyncTimeout(Duration.ofSeconds(20).toMillis());
        });
    }

}

執行結果

Tomcat started on port 8088 (http) with context path '/demo1'

切換 container

假設要把 tomcat 換成 undertow,修改 pom.xml

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-undertow</artifactId>
        </dependency>

啟動時,可看到換成了Undertow

[           main] o.s.b.w.e.undertow.UndertowWebServer     : Undertow started on port 8081 (http) with context path '/demo1'

SSL

spring boot 可可定 ssl license,支援 https

自己產生 SSL 憑證

keytool -genkeypair -alias https -keyalg RSA -keysize 2048 -keystore keystore.jks -validity 36500
keytool -importkeystore -srckeystore keystore.jks -destkeystore keystore.p12 -deststoretype pkcs12

把 keystore.jks, keystore.p12 放到 resources 目錄

application.yml

server:
  port: 8443
  ssl:
    protocol: TLS
    # key-store-type={JKS|PKCS12}
    key-store-type: PKCS12
    key-store: classpath:keystore.p12
    key-store-password: password

這樣就能瀏覽網頁 https://localhost:8443/


如果需要同時支援 http 及 https,就把 https 放在上面設定檔中。另外用程式的方式,啟動支援 http

package tw.com.test.demo1.config;

import lombok.extern.slf4j.Slf4j;
import org.apache.catalina.connector.Connector;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;
import org.springframework.boot.web.servlet.server.ServletWebServerFactory;
import org.springframework.context.annotation.Bean;

@Configuration
public class ServerConfig {

    @Bean
    public ServletWebServerFactory servletContainer() {
        TomcatServletWebServerFactory tomcat = new TomcatServletWebServerFactory();
        tomcat.addAdditionalTomcatConnectors(createStandardConnector());
        return tomcat;
    }

    private Connector createStandardConnector() {
        Connector connector = new Connector("org.apache.coyote.http11.Http11NioProtocol");
        connector.setPort(8080);
        return connector;
    }
}

啟動後會看到

Tomcat started on ports 8443 (https), 8080 (http) with context path '/demo1'

session persistence

server:
  port: 8080
  servlet:
    context-path: /demo1
    session:
      persistent: true
      store-dir: sessions
      tracking-modes:
        - cookie
        - url

server 必須要用 kill -15 pid 不能用 kill -9 pid 刪除 process,否則不會觸發 session persistence


shutdown graceful

server:
  shutdown: graceful

spring:
  lifecycle:
    # shutdown 的 timeout
    timeout-per-shutdown-phase: 20s

spring boot 的 graceful shudown 也是呼叫 JDK 的 Runtime.getRuntime().addShutdownHook()

不建議用 kill -9 pid 的方式 kill process,一般應該使用 kill -15 pid

自訂 Web 設定

如果不想使用 spring boot 預設的 web configuration,可透過 WebMvcConfigurer interface 自訂

ex: 增加 interceptor, 格式化器, 資源處理器

@Configuration
public class WebConfig implements WebMvcConfigurer {
}

註冊 interceptor

package tw.com.test.demo1.config;

import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;

@Slf4j
@Component
public class LoginInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        log.info("LoginInterceptor preHandle getRequestURI={},  getServletPath={}", request.getRequestURI(), request.getServletPath());
        HttpSession session = request.getSession();
        String userSession = (String) session.getAttribute("userSession");
        if( userSession==null) {
//            log.info("request.getContextPath()={}", request.getContextPath());
            String contextPath = request.getContextPath();
            response.sendRedirect(contextPath+"/index.html");
            return false;
        } else {
            return true;
        }
    }
}

取得 http session 裡面的 "userSession" 判斷是否已經登入

WebConfig.java

package tw.com.test.demo1.config;

import lombok.RequiredArgsConstructor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
@RequiredArgsConstructor
public class WebConfig implements WebMvcConfigurer {

    private final LoginInterceptor loginInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(loginInterceptor)
//                .addPathPatterns("/**")
                .excludePathPatterns("/**/*.{jsp|html|css|js|png|jpg}")
                .excludePathPatterns("/**/error")
                .excludePathPatterns("/static/**");
    }
}

application.yml

server:
  shutdown: graceful
  port: 8080
  servlet:
    context-path: /demo1

在 static 目錄加上測試檔案

  • /static/index.html

  • /static/js/test.js

  • /static/css/test.css

啟動後測試


Message Converter

讓 Java Bean 可以自動轉換為 JSON/XML

spring boot 支援以下三種 JSON libary

如覺得 JacksonHttpMessageConvertersConfiguration 不符合要求,可覆蓋

@Configuration
@RequiredArgsConstructor
public class WebConfig implements WebMvcConfigurer {

    @Bean
    public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() {
        MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

        SimpleModule module = new SimpleModule();
        module.addDeserializer(String.class, new StringWithoutSpaceDeserializer(String.class));
        mapper.registerModule(module);

        converter.setObjectMapper(mapper);
        return converter;
    }
}

StringWithoutSpaceDeserializer.java

package tw.com.test.demo1.handler;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
import org.apache.commons.lang3.StringUtils;

import java.io.IOException;

public class StringWithoutSpaceDeserializer extends StdDeserializer<String> {

    private static final long serialVersionUID = -1L;

    public StringWithoutSpaceDeserializer(Class<String> vc) {
        super(vc);
    }

    @Override
    public String deserialize(JsonParser p, DeserializationContext deserializationContext) throws IOException {
        return StringUtils.trimToEmpty(p.getText());
    }

}

這個 JSON 轉換器,設定 FAIL_ON_UNKNOWN_PROPERTIES 為 false。並配置一個 StringWithoutSpaceDeserializer,可過濾 http 參數首尾的空白


如果不用覆蓋的做法,可以增加自訂轉換器。也就是自訂 HttpMessageConverters

ref: # Day18 - HttpMessageConverter

ref: # HttpMessageConverter详解


類別轉換器

Converter 介面可以轉換參數的類別

package tw.com.test.demo1.config;

import lombok.RequiredArgsConstructor;
import org.springframework.context.annotation.Configuration;
import org.springframework.format.FormatterRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import tw.com.test.demo1.handler.CustomConverter;

@Configuration
@RequiredArgsConstructor
public class WebConfig implements WebMvcConfigurer {

    @Override
    public void addFormatters(FormatterRegistry registry) {
        registry.addConverter(new CustomConverter());
    }

}

CustomerConverter.java

package tw.com.test.demo1.handler;

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;
import org.springframework.core.convert.converter.Converter;

@Slf4j
public class CustomConverter implements Converter<String, String> {

    @Override
    public String convert(String source) {
        if (StringUtils.isNotEmpty(source)) {
            source = source.trim();
        }
        return source;
    }

}

註冊 Servlet, Filter, Listener

手動註冊

spring boot 有以下三種註冊類別

  • ServletRegistrationBean

  • FilterRegistrationBean

  • ServletListenerRegistrationBean

以下是 Servlet 的 sample

@Configuration
@RequiredArgsConstructor
public class WebConfig implements WebMvcConfigurer {

    @Bean
    public ServletRegistrationBean registerServlet() {
        ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean(new RegisterServlet(), "/registerServlet");
        servletRegistrationBean.addInitParameter("name", "username");
        servletRegistrationBean.addInitParameter("sex", "male");
        servletRegistrationBean.setIgnoreRegistrationFailure(true);
        return servletRegistrationBean;
    }

}

RegisterServelet.java

package tw.com.test.demo1.servlet;

import jakarta.servlet.ServletOutputStream;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;

public class RegisterServlet extends HttpServlet {

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        String name = getServletConfig().getInitParameter("name");
        String sex = getServletConfig().getInitParameter("sex");

        ServletOutputStream outputStream = resp.getOutputStream();
        outputStream.println("name is " + name);
        outputStream.println("sex is " + sex);
    }

}

瀏覽網頁 http://localhost:8080/demo1/registerServlet 可看到結果

name is username
sex is male

自動掃描註冊

Servlet 3.0 以後不需要 web.xml,所有元件都可透過 annotation 註冊

  • @WebServlet

  • @WebFilter

  • @WebListener

因為 spring boot 內嵌的 tomcat 不會執行 ServletContainerInitializer interface。WebConfig 必須加上 @ServletComponentScan ,開啟掃描功能。

@Configuration
@RequiredArgsConstructor
@ServletComponentScan
public class WebConfig implements WebMvcConfigurer {

}

filter, servlet, listener 必須要在 WebConfig 的 sub package 裡面

JavaServlet.java

package tw.com.test.demo1.config.servlet;

import jakarta.servlet.ServletOutputStream;
import jakarta.servlet.annotation.WebInitParam;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;

@WebServlet(name = "javaServlet", urlPatterns = "/javaServlet", asyncSupported = true, initParams = {@WebInitParam(name = "name", value = "javaServlet"), @WebInitParam(name = "sex", value = "male")})
public class JavaServlet extends HttpServlet {

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        String name = getServletConfig().getInitParameter("name");
        String sex = getServletConfig().getInitParameter("sex");

        ServletOutputStream outputStream = resp.getOutputStream();
        outputStream.println("name is " + name);
        outputStream.println("sex is " + sex);

    }

}

JavaFilter.java

package tw.com.test.demo1.config.servlet;

import jakarta.servlet.*;
import jakarta.servlet.annotation.WebFilter;
import jakarta.servlet.annotation.WebInitParam;
import lombok.extern.slf4j.Slf4j;

import java.io.IOException;

@WebFilter(filterName = "javaFilter", urlPatterns = "/*", initParams = {@WebInitParam(name = "name", value = "javaFilter"), @WebInitParam(name = "code", value = "123456")})
@Slf4j
public class JavaFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

        String name = filterConfig.getInitParameter("name");
        String code = filterConfig.getInitParameter("code");
        log.info("JavaFilter init, name={}, code={}", name, code);
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        log.info("JavaFilter doFilter");
        chain.doFilter(request, response);
    }

    @Override
    public void destroy() {
        log.info("JavaFilter destroy");
    }

}

ContextListener.java

package tw.com.test.demo1.config.listener;


import jakarta.servlet.ServletContextEvent;
import jakarta.servlet.ServletContextListener;
import jakarta.servlet.annotation.WebListener;
import lombok.extern.slf4j.Slf4j;

@Slf4j
@WebListener
public class ContextListener implements ServletContextListener {

    @Override
    public void contextInitialized(ServletContextEvent event) {
        log.info("application contextInitialized started");
    }

    @Override
    public void contextDestroyed(ServletContextEvent event) {
        log.info("application contextDestroyed stopped");
    }
}

SessionListener.java

package tw.com.test.demo1.config.listener;

import jakarta.servlet.annotation.WebListener;
import jakarta.servlet.http.HttpSessionAttributeListener;
import jakarta.servlet.http.HttpSessionBindingEvent;
import jakarta.servlet.http.HttpSessionEvent;
import jakarta.servlet.http.HttpSessionListener;
import lombok.extern.slf4j.Slf4j;

@Slf4j
@WebListener("Session listener for the application")//description of the listener
public class SessionListener implements HttpSessionListener, HttpSessionAttributeListener {

    @Override
    public void attributeAdded(HttpSessionBindingEvent event) {
        log.info("SessionListener attributeAdded event={}", event);
    }

    @Override
    public void attributeRemoved(HttpSessionBindingEvent event) {
        log.info("SessionListener attributeRemoved event={}", event);
    }

    @Override
    public void attributeReplaced(HttpSessionBindingEvent event) {
        log.info("SessionListener attributeReplaced event={}", event);
    }

    @Override
    public void sessionCreated(HttpSessionEvent event) {
        log.info("SessionListener sessionCreated event={}", event);
    }

    @Override
    public void sessionDestroyed(HttpSessionEvent event) {
        log.info("SessionListener sessionDestroyed event={}", event);
    }

}

啟動後,瀏覽網頁 http://localhost:8080/demo1/javaServlet

2024-11-19T16:52:05.640+08:00  INFO 7277 --- [           main] tw.com.test.demo1.Demo1Application       : Starting Demo1Application using Java 17 with PID 7277 (/Users/charley/project/idea/book/test/demo1/target/classes started by charley in /Users/charley/project/idea/book/test/demo1)
2024-11-19T16:52:05.653+08:00  INFO 7277 --- [           main] tw.com.test.demo1.Demo1Application       : No active profile set, falling back to 1 default profile: "default"
2024-11-19T16:52:06.982+08:00  INFO 7277 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port 8080 (http)
2024-11-19T16:52:06.998+08:00  INFO 7277 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2024-11-19T16:52:06.998+08:00  INFO 7277 --- [           main] o.apache.catalina.core.StandardEngine    : Starting Servlet engine: [Apache Tomcat/10.1.31]
2024-11-19T16:52:07.081+08:00  INFO 7277 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/demo1]  : Initializing Spring embedded WebApplicationContext
2024-11-19T16:52:07.081+08:00  INFO 7277 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1271 ms
2024-11-19T16:52:07.143+08:00  INFO 7277 --- [           main] t.c.t.d.config.listener.ContextListener  : application contextInitialized started
2024-11-19T16:52:07.150+08:00  INFO 7277 --- [           main] t.c.t.demo1.config.servlet.JavaFilter    : JavaFilter init, name=javaFilter, code=123456
2024-11-19T16:52:07.317+08:00  INFO 7277 --- [           main] o.s.b.a.w.s.WelcomePageHandlerMapping    : Adding welcome page: class path resource [static/index.html]
2024-11-19T16:52:07.650+08:00  INFO 7277 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port 8080 (http) with context path '/demo1'
2024-11-19T16:52:07.665+08:00  INFO 7277 --- [           main] tw.com.test.demo1.Demo1Application       : Started Demo1Application in 2.869 seconds (process running for 4.439)
2024-11-19T16:52:43.224+08:00  INFO 7277 --- [nio-8080-exec-1] t.c.t.demo1.config.servlet.JavaFilter    : JavaFilter doFilter
2024-11-19T16:53:49.996+08:00  INFO 7277 --- [ionShutdownHook] o.s.b.w.e.tomcat.GracefulShutdown        : Commencing graceful shutdown. Waiting for active requests to complete
2024-11-19T16:53:50.007+08:00  INFO 7277 --- [tomcat-shutdown] o.s.b.w.e.tomcat.GracefulShutdown        : Graceful shutdown complete
2024-11-19T16:53:50.016+08:00  INFO 7277 --- [ionShutdownHook] t.c.t.demo1.config.servlet.JavaFilter    : JavaFilter destroy
2024-11-19T16:53:50.017+08:00  INFO 7277 --- [ionShutdownHook] t.c.t.d.config.listener.ContextListener  : application contextDestroyed stopped

動態註冊

InitServlet.java

package tw.com.test.demo1.config.servlet;

import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;

public class InitServlet extends HttpServlet {

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        String name = getServletConfig().getInitParameter("name");
        String sex = getServletConfig().getInitParameter("sex");

        resp.getOutputStream().println("name is " + name);
        resp.getOutputStream().println("sex is " + sex);

    }

}

有兩種方法

  1. @Bean
@Configuration
@RequiredArgsConstructor
public class WebConfig implements WebMvcConfigurer {

    @Bean
    public ServletContextInitializer servletContextInitializer() {
        return (servletContext) -> {
            ServletRegistration initServlet = servletContext.addServlet("initServlet", InitServlet.class);
            initServlet.addMapping("/initServlet");
            initServlet.setInitParameter("name", "initServlet");
            initServlet.setInitParameter("sex", "male");
        };
    }
}
  1. @Component
package tw.com.test.demo1.config;

import jakarta.servlet.ServletContext;
import jakarta.servlet.ServletException;
import jakarta.servlet.ServletRegistration;
import org.springframework.boot.web.servlet.ServletContextInitializer;
import org.springframework.stereotype.Component;
import tw.com.test.demo1.config.servlet.InitServlet;

@Component
public class ServletConfig implements ServletContextInitializer {
    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        ServletRegistration initServlet = servletContext.addServlet("initServlet2", InitServlet.class);
        initServlet.addMapping("/initServlet2");
        initServlet.setInitParameter("name", "initServlet2");
        initServlet.setInitParameter("sex", "female");
    }
}

兩種 servlet url 都是由 InitServlet 處理

http://localhost:8080/demo1/initServlet

http://localhost:8080/demo1/initServlet2


靜態資源處理

spring boot 預設會載入 classpath 以下目錄的資源

  • /static

  • /public

  • /resources

  • /META-INF/resources

可用這個參數修改

spring:
  web:
    resources:
      static-locations: classpath:/static,classpath:/public,classpath:/resources,classpath:/META-INF/resources

預設會把靜態資源映射到 /** 路徑,可以用以下方式修改

spring:
  mvc:
    static-path-pattern: "/pub/**"

spring MVC 預設使用 ResourceHttpRequestHandler 處理靜態資源,也可以實作自己的處理器。這邊增加了兩個靜態資源映射

@Configuration
@RequiredArgsConstructor
public class WebConfig implements WebMvcConfigurer {

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static/**").addResourceLocations("classpath:/static/");
        registry.addResourceHandler("/assets/**").addResourceLocations("classpath:/assets/");
    }
}