Apache POI 是 Poor Obfuscation Implementation 的縮寫，其目的是建立與讀取 Office Open XML（OOXML）標準和微軟的OLE 2復合文檔格式（OLE2）的Java API。
主要的元件有：
- Excel (SS=HSSF+XSSF)
- Word (HWPF+XWPF)
- PowerPoint (HSLF+XSLF)
- OpenXML4J (OOXML)
- OLE2 Filesystem (POIFS): OLE 2 Compound Document format 的Java Implementation
- OLE2 Document Props (HPSF): Open Packaging Conventions (OPC) 的 Java Implementation
- Outlook (HSMF)
- Visio (HDGF+XDGF)
- TNEF (HMEF): Microsoft's TNEF (Transport Neutral Encoding Format)，也就是 winmail.dat，用在 Outlook 跟 Exchange -Publisher (HPBF): Publisher file format
怎麼會命名成 Poor Obfuscation Implementation
POI 套件從 2001 年就開始了初始專案，由於 MS 的封閉特性，Office 檔案格式並沒有開放，作者就戲稱這個檔案格式是非常難以被理解，很混亂的一種檔案，就用了 Poor Obfuscation 這兩個字，當然還是成功地被 reverse-engineered，成就了這個專案，除了 MS Office 軟體之外，我們現在也可以用程式產生 Office 檔案。
後來在 2008 年，MS終於向 Sourcesense 提交了 ISO/IEC 29500:2008 Office Open XML file formats，等於是開放了 OOXML 的 Office 檔案的標準，POI 就以這個規格，實作了接下來的函式庫，支援這個 OOXML 的標準規格。
HSSF, XSSF
Excel 分為兩種檔案格式，比較舊的是 HSSFWorkbook，檔案格式為 Excel 1997-2003 版的Excel，副檔名是 xls，XSSFWorkbook 是 Excel 2007-10 的版本，副檔名是 xlsx。
基本的階層概念為一個 xlsx 檔案 XSSFWorkbook，裡面有多個工作表 XSSFSheet，每一個 Sheet 下面有一個表格，裡面有多列資料 XSSFRow，每列資料中有多欄資料儲存格 XSSFCell。
文件的資料階層是
XSSFWorkbook -> XSSFSheet -> XSSFRow -> XSSFCellRead/Write XLSX file in Java
以下的 Java 程式會產生一個 Test.xlsx 檔案，包含兩個工作表。如果要處理的是 xls 檔案，只要把所有 XSSF 開頭的 class 都換成 HSSF 就可以了。
import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.hssf.util.HSSFColor;
import org.apache.poi.ss.usermodel.CellStyle;
import org.apache.poi.ss.usermodel.Font;
import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
public class PoiTest {
public static void readXLSXFile() throws IOException {
InputStream ExcelFileToRead = new FileInputStream("Test.xlsx");
XSSFWorkbook wb = new XSSFWorkbook(ExcelFileToRead);
XSSFSheet sheet = wb.getSheetAt(0);
XSSFRow row;
XSSFCell cell;
Iterator rows = sheet.rowIterator();
while (rows.hasNext()) {
row = (XSSFRow) rows.next();
Iterator cells = row.cellIterator();
while (cells.hasNext()) {
cell = (XSSFCell) cells.next();
if (cell.getCellType() == XSSFCell.CELL_TYPE_STRING) {
System.out.print(cell.getStringCellValue() + " ");
} else if (cell.getCellType() == XSSFCell.CELL_TYPE_NUMERIC) {
System.out.print(cell.getNumericCellValue() + " ");
} else {
//U Can Handel Boolean, Formula, Errors
}
}
System.out.println();
}
}
public static void writeXLSXFile() throws IOException {
String excelFileName = "Test.xlsx";//name of excel file
XSSFWorkbook wb = new XSSFWorkbook();
Font titlefont = wb.createFont();
titlefont.setColor(HSSFColor.BLACK.index);//顏色
titlefont.setBoldweight(Font.BOLDWEIGHT_BOLD); //粗體
CellStyle styleRow1 = wb.createCellStyle();
styleRow1.setFillForegroundColor(HSSFColor.LIGHT_GREEN.index);//填滿顏色
styleRow1.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
styleRow1.setFont(titlefont);//設定字體
styleRow1.setAlignment(HSSFCellStyle.ALIGN_CENTER);//水平置中
styleRow1.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);//垂直置中
//設定框線
styleRow1.setBorderBottom((short)1);
styleRow1.setBorderTop((short)1);
styleRow1.setBorderLeft((short)1);
styleRow1.setBorderRight((short)1);
styleRow1.setWrapText(true);//自動換行
CellStyle styleRow2 = wb.createCellStyle();
styleRow2.setAlignment(HSSFCellStyle.ALIGN_CENTER);//水平置中
styleRow2.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);//垂直置中
styleRow2.setBorderBottom((short)1);
styleRow2.setBorderTop((short)1);
styleRow2.setBorderLeft((short)1);
styleRow2.setBorderRight((short)1);
styleRow2.setWrapText(true);//自動換行
String sheetName2 = "工作表2";//name of sheet
XSSFSheet sheet2 = wb.createSheet(sheetName2);
XSSFRow titlerow = sheet2.createRow(0);
for (int c = 0; c < 6; c++) {
XSSFCell cell = titlerow.createCell(c);
cell.setCellStyle(styleRow1);
cell.setCellValue("標題 Cell 0 " + c);
sheet2.autoSizeColumn(c); //自動調整欄位寬度
}
for (int r = 1; r < 10; r++) {
XSSFRow row = sheet2.createRow(r);
for (int c = 0; c < 5; c++) {
XSSFCell cell = row.createCell(c);
cell.setCellStyle(styleRow2);
cell.setCellValue("中文 Cell " + r + " " + c);
sheet2.autoSizeColumn(c); //自動調整欄位寬度
}
XSSFCell cell = row.createCell(5);
cell.setCellValue(100);
sheet2.autoSizeColumn(5);
}
String sheetName = "工作表";//name of sheet
XSSFSheet sheet = wb.createSheet(sheetName);
for (int r = 0; r < 5; r++) {
XSSFRow row = sheet.createRow(r);
for (int c = 0; c < 5; c++) {
XSSFCell cell = row.createCell(c);
if( r==0 ) {
cell.setCellStyle(styleRow1);
} else {
cell.setCellStyle(styleRow2);
}
cell.setCellValue("中文 title " + r + " " + c);
sheet.autoSizeColumn(c); //自動調整欄位寬度
}
}
FileOutputStream fileOut = new FileOutputStream(excelFileName);
wb.write(fileOut);
fileOut.flush();
fileOut.close();
}
public static void main(String[] args) throws IOException {
writeXLSXFile();
readXLSXFile();
}
}Read/Write XLSX file in Scala
將上面的 Java 版本的程式翻譯成 Scala 的寫法，其中有個部分要注意，在 Java 程式中，有一段 XSSFCell.CELLTYPESTRING，使用了 XSSFCell 實作的 Cell 介面，在 Cell 介面中定義的常數 CELLTYPESTRING。
雖然 Scala 跟 Java 相容，但是在 Scala 沒辦法直接使用 Java 介面裡面定義的常數，所以我們只有再用 Scala object 再定義一次常數。
import java.io.{FileInputStream, FileOutputStream, IOException, InputStream}
import java.util.Iterator
import org.apache.poi.hssf.util.HSSFColor
import org.apache.poi.ss.usermodel.{CellStyle, Font}
import org.apache.poi.xssf.usermodel.{XSSFCell, XSSFRow, XSSFSheet, XSSFWorkbook}
object Cell {
val CELL_TYPE_NUMERIC: Int = 0
val CELL_TYPE_STRING: Int = 1
val CELL_TYPE_FORMULA: Int = 2
val CELL_TYPE_BLANK: Int = 3
val CELL_TYPE_BOOLEAN: Int = 4
val CELL_TYPE_ERROR: Int = 5
}
object CellStyle {
val ALIGN_GENERAL:Short = 0
val ALIGN_LEFT:Short = 1
val ALIGN_CENTER:Short = 2
val ALIGN_RIGHT:Short = 3
val ALIGN_FILL:Short = 4
val ALIGN_JUSTIFY:Short = 5
val ALIGN_CENTER_SELECTION:Short = 6
val VERTICAL_TOP:Short = 0
val VERTICAL_CENTER:Short = 1
val VERTICAL_BOTTOM:Short = 2
val VERTICAL_JUSTIFY:Short = 3
val BORDER_NONE:Short = 0
val BORDER_THIN:Short = 1
val BORDER_MEDIUM:Short = 2
val BORDER_DASHED:Short = 3
val BORDER_HAIR:Short = 7
val BORDER_THICK:Short = 5
val BORDER_DOUBLE:Short = 6
val BORDER_DOTTED:Short = 4
val BORDER_MEDIUM_DASHED:Short = 8
val BORDER_DASH_DOT:Short = 9
val BORDER_MEDIUM_DASH_DOT:Short = 10
val BORDER_DASH_DOT_DOT:Short = 11
val BORDER_MEDIUM_DASH_DOT_DOT:Short = 12
val BORDER_SLANTED_DASH_DOT:Short = 13
val NO_FILL:Short = 0
val SOLID_FOREGROUND:Short = 1
val FINE_DOTS:Short = 2
val ALT_BARS:Short = 3
val SPARSE_DOTS:Short = 4
val THICK_HORZ_BANDS:Short = 5
val THICK_VERT_BANDS:Short = 6
val THICK_BACKWARD_DIAG:Short = 7
val THICK_FORWARD_DIAG:Short = 8
val BIG_SPOTS:Short = 9
val BRICKS:Short = 10
val THIN_HORZ_BANDS:Short = 11
val THIN_VERT_BANDS:Short = 12
val THIN_BACKWARD_DIAG:Short = 13
val THIN_FORWARD_DIAG:Short = 14
val SQUARES:Short = 15
val DIAMONDS:Short = 16
val LESS_DOTS:Short = 17
val LEAST_DOTS:Short = 18
}
object ScalaPoiTest {
@throws(classOf[IOException])
def readXLSXFile {
val ExcelFileToRead: InputStream = new FileInputStream("Test.xlsx")
val wb: XSSFWorkbook = new XSSFWorkbook(ExcelFileToRead)
val sheet: XSSFSheet = wb.getSheetAt(0)
var row: XSSFRow = null
var cell: XSSFCell = null
val rows: Iterator[_] = sheet.rowIterator
while (rows.hasNext) {
row = rows.next.asInstanceOf[XSSFRow]
val cells: Iterator[_] = row.cellIterator
while (cells.hasNext) {
cell = cells.next.asInstanceOf[XSSFCell]
if (cell.getCellType == Cell.CELL_TYPE_STRING) {
System.out.print(cell.getStringCellValue + " ")
}
else if (cell.getCellType == Cell.CELL_TYPE_NUMERIC) {
System.out.print(cell.getNumericCellValue + " ")
}
else {
}
}
System.out.println
}
}
@throws(classOf[IOException])
def writeXLSXFile {
val excelFileName: String = "Test.xlsx"
val wb: XSSFWorkbook = new XSSFWorkbook
val titlefont: Font = wb.createFont
titlefont.setColor(HSSFColor.BLACK.index)
titlefont.setBoldweight(Font.BOLDWEIGHT_BOLD)
val styleRow1: CellStyle = wb.createCellStyle
styleRow1.setFillForegroundColor(HSSFColor.LIGHT_GREEN.index)
styleRow1.setFillPattern(CellStyle.SOLID_FOREGROUND)
styleRow1.setFont(titlefont)
styleRow1.setAlignment(CellStyle.ALIGN_CENTER)
styleRow1.setVerticalAlignment(CellStyle.VERTICAL_CENTER)
styleRow1.setBorderBottom(1)
styleRow1.setBorderTop(1)
styleRow1.setBorderLeft(1)
styleRow1.setBorderRight(1)
styleRow1.setWrapText(true)
val styleRow2: CellStyle = wb.createCellStyle
styleRow2.setAlignment(CellStyle.ALIGN_CENTER)
styleRow2.setVerticalAlignment(CellStyle.VERTICAL_CENTER)
styleRow2.setBorderBottom(1)
styleRow2.setBorderTop(1)
styleRow2.setBorderLeft(1)
styleRow2.setBorderRight(1)
styleRow2.setWrapText(true)
val sheetName2: String = "Sheet2"
val sheet2: XSSFSheet = wb.createSheet(sheetName2)
val titlerow: XSSFRow = sheet2.createRow(0)
for (c <- 0 to 6) {
val cell: XSSFCell = titlerow.createCell(c)
cell.setCellStyle(styleRow1)
cell.setCellValue("標題 Cell 0 " + c)
sheet2.autoSizeColumn(c)
}
for (r <- 1 to 5) {
val row: XSSFRow = sheet2.createRow(r)
for (c <- 0 to 5) {
val cell: XSSFCell = row.createCell(c)
cell.setCellValue("中文 Cell " + r + " " + c)
sheet2.autoSizeColumn(c)
}
val cell: XSSFCell = row.createCell(6)
cell.setCellValue(100)
sheet2.autoSizeColumn(6)
}
val sheetName: String = "Sheet"
val sheet: XSSFSheet = wb.createSheet(sheetName)
for (r <- 0 to 4) {
val row: XSSFRow = sheet.createRow(r)
for (c <- 0 to 4) {
val cell: XSSFCell = row.createCell(c)
cell.setCellValue("中文 Cell " + r + " " + c)
sheet.autoSizeColumn(c)
}
}
val fileOut: FileOutputStream = new FileOutputStream(excelFileName)
wb.write(fileOut)
fileOut.flush
fileOut.close
}
@throws(classOf[IOException])
def main(args: Array[String]) {
writeXLSXFile
readXLSXFile
}
}Scala 不能使用 Java Interface constant members
以下這個 stackoverflow 討論中，有談到剛剛在 Scala 版本中遇到的問題：Scala can not resolve inherited Java interface constant members
基本上沒有什麼特殊的解決方案，在 Scala 就是不支援這樣子的寫法。
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