POI 简介
Apache POI 是Apache的开源项目，POI提供API给Java程序对Microsoft Offic 格式文档读和写的功能。
POI 结构说明
Excel包名称说明
| HSSF | XSSF | SXSSF | |
|---|---|---|---|
| 对应Excel版本 | 2003及2003版本以前 | 2007后版本 | 2007后版本 |
| 扩展名 | .xls | .xlsx | .xlsx |
| 区别 | 最常用的方式，但是不能超过65535行，超出65536条就会报错，此方式因不足7万行所以一般不会内存溢出（OOM） | 突破HSSF 65535行的局限(1048576行，16384列)，不过就伴随着一个问题内存溢出，原因是你创建的是存在内存的并没有持久化 | POI 3.8 开始，提供基于XSSF低内存占用的SXSSF方式。它只会保存最新的excel rows在内存里供查看，在此之前的都会被写入到硬盘里。被写入硬盘的rows是不可见/不可访问的。只有内存里才可以访问到 |
SXSSF与XSSF的对比：
| XSSF | XSSF | |
|---|---|---|
| 访问量 | 访问全部 | 访问一定数量的数据 |
| Sheet.clone() | 支持 | 不支持 |
| 公式求值 | 支持 | 不支持 |
| 更换表头 | 可以 | 不可，因为已经提前把数据写入硬盘就不能修改 |
引入pom
org.apache.poi
poi-excelant
4.1.0
创建 HSSFWorkbook，
Workbook workbook = new HSSFWorkbook();
try(OutputStream fileOut = new FileOutputStream("workbook.xls")){
workbook.write(fileOut);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
创建 XSSFWorkboook
Workbook workbook = new XSSFWorkbook();
try(OutputStream fileOut = new FileOutputStream("workbook.xlsx")){
workbook.write(fileOut);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
以上两种方法创建出来的文件是不能直接打开的，Excel最少要有一张Sheet 工作簿存在。
创建Sheet
Workbook workbook = new HSSFWorkbook();
/**
* 请注意，工作表名称不能超过31个字符，且不能包含以下字符：
* 0x0000、0x0003、冒号(:)、反斜杠(\)、星号(*)、问号(?)、正斜杠(/)、方括号([])
* WorkbookUtil.createSafeSheetName(sheetName) 此方法可以将无效字符转化为空格
* 已存在就不能创建，只能 workbook.getSheet("sheet")
*/
Sheet sheet = workbook.createSheet("sheet");
try(OutputStream fileOut = new FileOutputStream("workbook.xls")){
workbook.write(fileOut);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
创建单元格并设置单元格内容
Workbook workbook = new HSSFWorkbook();
CreationHelper creationHelper = workbook.getCreationHelper();
Sheet sheet = workbook.createSheet("sheet");
//创建下标为0（首行，下标从0开始）行单元格(1行)，可以重复创建
Row row = sheet.createRow(0);
//创建0行下标为0的单元格(A1单元格)，可以重复创建
Cell cell = row.createCell(0);
//A1单元格设置内容为 1
cell.setCellValue(1);
//B1单元格设置内容为 1.2
row.createCell(1).setCellValue(1.2);
//C1单元格设置内容为 string
row.createCell(2).setCellValue(
creationHelper.createRichTextString("string"));
//D1单元格设置内容为 true
row.createCell(3).setCellValue(true);
//E1单元格设置日期，无格式
row.createCell(4).setCellValue(new Date());
//设置单元格格式
CellStyle cellStyle = workbook.createCellStyle();
cellStyle.setDataFormat(creationHelper.createDataFormat().getFormat("m/d/yy h:mm"));
//F1单元格设置日期并格式化
Cell F1 = row.createCell(5);
F1.setCellStyle(cellStyle);
F1.setCellValue(new Date());
//F1单元格设置日期并格式化
Cell G1 = row.createCell(6);
G1.setCellStyle(cellStyle);
G1.setCellValue(Calendar.getInstance());
try (OutputStream fileOut = new FileOutputStream("workbook.xls")) {
workbook.write(fileOut);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
设置不同类型的单元格
Workbook workbook = new HSSFWorkbook();
Sheet sheet = workbook.createSheet("sheet");
Row row = sheet.createRow(2);
row.createCell(0).setCellValue(1.1);
row.createCell(1).setCellValue(new Date());
row.createCell(2).setCellValue(Calendar.getInstance());
row.createCell(3).setCellValue("a string");
row.createCell(4).setCellValue(true);
row.createCell(5).setCellType(CellType.ERROR);
try (OutputStream fileOut = new FileOutputStream("workbook.xls")) {
workbook.write(fileOut);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
使用FIle或FileInputStream打开Excel，，只能打开已存在的Excel文件
/**
* 当打开一个Excel 文件(.xls或者.xlsx)时，可以从File或者FileInputStream打开
* 使用File可以减少内存的消耗，需要时间较长
* 使用FileInputStream需要更多内存，因为必须缓冲这个文件
*/
// 使用文件打开 Excel
Workbook file = WorkbookFactory.create(new File("workbook.xls"));
// 使用 InputStream 打开 Excel,需要时间较短
Workbook inputStream = WorkbookFactory.create(new FileInputStream("workbook.xls"));
使用HSSFWorkbook或XSSFWorkbook，通常应通过POIFSFileSystem或者OPCPackage来控制生命周期（包括完成后关闭文件），只能打开已存在的Excel文件
POIFSFileSystem fileSystem = new POIFSFileSystem(new File("workbook.xls"));
HSSFWorkbook workbook = new HSSFWorkbook(fileSystem.getRoot(), true);
fileSystem.close();
POIFSFileSystem fileSystem = new POIFSFileSystem(new FileInputStream("workbook.xls"));
HSSFWorkbook workbook = new HSSFWorkbook(fileSystem.getRoot(), true);
fileSystem.close();
OPCPackage opcPackage = OPCPackage.open(new File("workbook.xls"));
XSSFWorkbook workbook = new XSSFWorkbook(pkg);
opcPackage.close();
OPCPackage opcPackage = OPCPackage.open(new FileInputStream("workbook.xls"));
XSSFWorkbookworkbook = new XSSFWorkbook(pkg);
opcPackage.close();
对齐方式
@org.junit.Test
public void excelTest() throws IOException, InvalidFormatException {
POIFSFileSystem fileSystem = new POIFSFileSystem(new File("workbook.xls"));
HSSFWorkbook workbook = new HSSFWorkbook(fileSystem.getRoot(), true);
//文件中已经存在 "sheet" ，直接获取不需要创建
Sheet sheet = workbook.getSheet("sheet");
Row row = sheet.createRow(2);
//设置行高
row.setHeightInPoints(30);
createCell(workbook, row, 0, HorizontalAlignment.CENTER, VerticalAlignment.BOTTOM);
createCell(workbook, row, 1, HorizontalAlignment.CENTER_SELECTION, VerticalAlignment.BOTTOM);
createCell(workbook, row, 2, HorizontalAlignment.FILL, VerticalAlignment.CENTER);
createCell(workbook, row, 3, HorizontalAlignment.GENERAL, VerticalAlignment.CENTER);
createCell(workbook, row, 4, HorizontalAlignment.JUSTIFY, VerticalAlignment.JUSTIFY);
createCell(workbook, row, 5, HorizontalAlignment.LEFT, VerticalAlignment.TOP);
createCell(workbook, row, 6, HorizontalAlignment.RIGHT, VerticalAlignment.TOP);
try (OutputStream fileOut = new FileOutputStream("workbook.xls")) {
workbook.write(fileOut);
}
workbook.close();
fileSystem.close();
}
/**
* 创建一个单元格并以某种方式对齐
*
* @param workbook 文件
* @param row Excel行对象
* @param column Excel第几列
* @param halign 水平对齐方式 [GENERAL（常规）,LEFT（左对齐）,CENTER（水平居中）,RIGHT（右对齐）,FILL（填充对齐）,JUSTIFY（两端对齐）,CENTER_SELECTION（跨列居中）,DISTRIBUTED（分散对齐）]
* @param valign 垂直对齐方式 [TOP（顶部对齐）,CENTER（垂直居中）,BOTTOM（底部对齐）,JUSTIFY（两端对齐）,DISTRIBUTED（分散对齐）]
*/
private static void createCell(Workbook workbook, Row row, int column, HorizontalAlignment halign, VerticalAlignment valign) {
Cell cell = row.createCell(column);
cell.setCellValue("Align It");
CellStyle cellStyle = workbook.createCellStyle();
cellStyle.setAlignment(halign);
cellStyle.setVerticalAlignment(valign);
cell.setCellStyle(cellStyle);
}
设置单元格边框
POIFSFileSystem fileSystem = new POIFSFileSystem(new File("workbook.xls"));
HSSFWorkbook workbook = new HSSFWorkbook(fileSystem.getRoot(), true);
Sheet sheet = workbook.getSheet("sheet");
Row row = sheet.createRow(1);
Cell cell = row.createCell(1);
cell.setCellValue(4);
CellStyle style = workbook.createCellStyle();
//设置下边框和颜色
style.setBorderBottom(BorderStyle.THIN);
style.setBottomBorderColor(IndexedColors.BLACK.getIndex());
//设置左边框和颜色
style.setBorderLeft(BorderStyle.THIN);
style.setLeftBorderColor(IndexedColors.GREEN.getIndex());
//设置右边框和颜色
style.setBorderRight(BorderStyle.THIN);
style.setRightBorderColor(IndexedColors.BLUE.getIndex());
//设置上边框边框和颜色
style.setBorderTop(BorderStyle.MEDIUM_DASHED);
style.setTopBorderColor(IndexedColors.BLACK.getIndex());
//设置单元格风格
cell.setCellStyle(style);
try (OutputStream fileOut = new FileOutputStream("workbook.xls")) {
workbook.write(fileOut);
}
workbook.close();
fileSystem.close();
遍历单元格
//workbook.iterator()
for (Sheet sheet : workbook) {
//sheet.iterator() 遍历已创建的行，跳过空行
for (Row row : sheet) {
///row.iterator() 遍历已创建的单元格，跳过空单元格
for (Cell cell : row) {
}
}
}
遍历所有单元格
POIFSFileSystem fileSystem = new POIFSFileSystem(new File("workbook.xls"));
HSSFWorkbook workbook = new HSSFWorkbook(fileSystem.getRoot(), true);
Sheet sheet = workbook.getSheet("sheet");
//获取有内容的首行下标，下标从0开始
int rowStart = sheet.getFirstRowNum();
//获取有内容的尾行下标，下标从0开始
int rowEnd = sheet.getLastRowNum();
for (int rowNum = rowStart; rowNum <= rowEnd; rowNum++) {
Row row = sheet.getRow(rowNum);
if (row == null) {
row = sheet.createRow(rowNum);
}
//空行的下标为-1，存在一条内容下标为0
int firstColumn = row.getFirstCellNum();
//空行下标为-1，下标从1开始
int lastColumn = row.getLastCellNum();
for (int cellNum = 0; cellNum < lastColumn; cellNum++) {
Cell cell = row.getCell(cellNum, Row.MissingCellPolicy.RETURN_BLANK_AS_NULL);
if (cell == null) {
cell = row.createCell(cellNum);
}
}
}
try (OutputStream fileOut = new FileOutputStream("workbook.xls")) {
workbook.write(fileOut);
}
workbook.close();
fileSystem.close();
获得不同格式单元格的值
POIFSFileSystem fileSystem = new POIFSFileSystem(new File("workbook.xls"));
HSSFWorkbook workbook = new HSSFWorkbook(fileSystem.getRoot(), true);
DataFormatter formatter = new DataFormatter();
Sheet sheet1 = workbook.getSheetAt(0);
for (Row row : sheet1) {
for (Cell cell : row) {
CellReference cellRef = new CellReference(row.getRowNum(), cell.getColumnIndex());
// 获取当前单元格的表示（例如 A1，B2）
System.out.print(cellRef.formatAsString() + " - ");
// 获取单元格值并应用任何的数据格式 (Date, 0.00, 1.23e9, $1.23, etc)
String text = formatter.formatCellValue(cell);
System.out.println(text);
// 或者，获取值并自动格式化
switch (cell.getCellTypeEnum()) {
case STRING:
System.out.println(cell.getRichStringCellValue().getString());
break;
case NUMERIC:
if (DateUtil.isCellDateFormatted(cell)) {
System.out.println(cell.getDateCellValue());
} else {
System.out.println(cell.getNumericCellValue());
}
break;
case BOOLEAN:
System.out.println(cell.getBooleanCellValue());
break;
case FORMULA:
System.out.println(cell.getCellFormula());
break;
case BLANK:
case ERROR:
case _NONE:
default:
System.out.println();
}
}
}
workbook.close();
fileSystem.close();
填充和颜色
POIFSFileSystem fileSystem = new POIFSFileSystem(new File("workbook.xls"));
HSSFWorkbook workbook = new HSSFWorkbook(fileSystem.getRoot(), true);
Sheet sheet = workbook.getSheet("sheet");
Row row = sheet.createRow(1);
// 填充图案
CellStyle style = workbook.createCellStyle();
style.setFillBackgroundColor(IndexedColors.AQUA.getIndex());
style.setFillPattern(FillPatternType.BIG_SPOTS);
Cell cell = row.createCell(1);
cell.setCellValue("X");
cell.setCellStyle(style);
// 填充颜色
style = workbook.createCellStyle();
style.setFillForegroundColor(IndexedColors.ORANGE.getIndex());
style.setFillPattern(FillPatternType.SOLID_FOREGROUND);
cell = row.createCell(2);
cell.setCellValue("X");
cell.setCellStyle(style);
try (OutputStream fileOut = new FileOutputStream("workbook.xls")) {
workbook.write(fileOut);
}
workbook.close();
fileSystem.close();
合并单元格
POIFSFileSystem fileSystem = new POIFSFileSystem(new File("workbook.xls"));
HSSFWorkbook workbook = new HSSFWorkbook(fileSystem.getRoot(), true);
Sheet sheet = workbook.getSheet("sheet");
Row row = sheet.createRow(1);
Cell cell = row.createCell(1);
String s = "This is a test of merging";
cell.setCellValue(s);
//合并单元格(B2,C2) 已经合并了的单元格就不能再次合并
sheet.addMergedRegion(new CellRangeAddress(
1, //first row (0-based)
1, //last row (0-based)
1, //first column (0-based)
2 //last column (0-based)
));
//合并后居中
cell = row.getCell(1);
CellStyle cellStyle = workbook.createCellStyle();
cellStyle.setAlignment(HorizontalAlignment.CENTER);
cellStyle.setVerticalAlignment(VerticalAlignment.CENTER);
cell.setCellStyle(cellStyle);
try (OutputStream fileOut = new FileOutputStream("workbook.xls")) {
workbook.write(fileOut);
}
workbook.close();
fileSystem.close();
字体设定
POIFSFileSystem fileSystem = new POIFSFileSystem(new File("workbook.xls"));
HSSFWorkbook workbook = new HSSFWorkbook(fileSystem.getRoot(), true);
Sheet sheet = workbook.getSheet("sheet");
Row row = sheet.createRow(1);
// Create a new font and alter it.
Font font = workbook.createFont();
//设置字号
font.setFontHeightInPoints((short)24);
//设置字体
font.setFontName("Courier New");
//设置黑体
font.setBold(true);
//设置斜体
font.setItalic(true);
//设置删除线
font.setStrikeout(true);
CellStyle style = workbook.createCellStyle();
style.setFont(font);
Cell cell = row.createCell(1);
cell.setCellValue("This is a test of fonts");
cell.setCellStyle(style);
try (OutputStream fileOut = new FileOutputStream("workbook.xls")) {
workbook.write(fileOut);
}
workbook.close();
fileSystem.close();
单元格换行
POIFSFileSystem fileSystem = new POIFSFileSystem(new File("workbook.xls"));
HSSFWorkbook workbook = new HSSFWorkbook(fileSystem.getRoot(), true);
Sheet sheet = workbook.getSheet("sheet");
Row row = sheet.createRow(2);
Cell cell = row.createCell(2);
cell.setCellValue("Use \n with word wrap on to create a new line");
//要使用换行符，要 wrap = true
CellStyle cs = workbook.createCellStyle();
cs.setWrapText(true);
cell.setCellStyle(cs);
//增加行高可以容量两行文本
row.setHeightInPoints((2 * sheet.getDefaultRowHeightInPoints()));
//自适应列宽
sheet.autoSizeColumn(2);
try (OutputStream fileOut = new FileOutputStream("workbook.xls")) {
workbook.write(fileOut);
}
workbook.close();
fileSystem.close();
小数处理
POIFSFileSystem fileSystem = new POIFSFileSystem(new File("workbook.xls"));
HSSFWorkbook workbook = new HSSFWorkbook(fileSystem.getRoot(), true);
Sheet sheet = workbook.getSheet("sheet");
CellStyle style;
DataFormat format = workbook.createDataFormat();
Row row;
Cell cell;
int rowNum = 0;
int colNum = 0;
row = sheet.createRow(rowNum++);
cell = row.createCell(colNum);
cell.setCellValue(111.25);
style = workbook.createCellStyle();
//小数点后保留1位
style.setDataFormat(format.getFormat("0.0"));
cell.setCellStyle(style);
row = sheet.createRow(rowNum++);
cell = row.createCell(colNum);
cell.setCellValue(111.25);
style = workbook.createCellStyle();
//小数点保留3位
style.setDataFormat(format.getFormat("0.000"));
cell.setCellStyle(style);
try (OutputStream fileOut = new FileOutputStream("workbook.xls")) {
workbook.write(fileOut);
}
workbook.close();
fileSystem.close();
筛选功能
POIFSFileSystem fileSystem = new POIFSFileSystem(new File("workbook.xls"));
HSSFWorkbook workbook = new HSSFWorkbook(fileSystem.getRoot(), true);
Sheet sheet = workbook.getSheet("sheet");
// 设置默认列宽
sheet.setDefaultColumnWidth(20);
HSSFFont font = workbook.createFont();
font.setFontName("黑体");
// 设置字体大小
font.setFontHeightInPoints((short) 13);
Row row = sheet.createRow((short) 0);
row.createCell(0).setCellValue("员工编号");
row.createCell(1).setCellValue("姓名");
row.createCell(2).setCellValue("绩效等级");
row.createCell(3).setCellValue("考核类型");
for (int i = 1; i <= 5; i++) {
row = sheet.createRow(i);
row.createCell(0).setCellValue(String.valueOf((int) (Math.random() * 100)));
row.createCell(1).setCellValue("Test" + i);
row.createCell(2).setCellValue("B");
row.createCell(3).setCellValue("月季考核");
}
//A1到D1 单元格筛选
CellRangeAddress c = CellRangeAddress.valueOf("A1:D1");
sheet.setAutoFilter(c);
try (OutputStream fileOut = new FileOutputStream("workbook.xls")) {
workbook.write(fileOut);
}
workbook.close();
fileSystem.close();
冻结单元格窗口
POIFSFileSystem fileSystem = new POIFSFileSystem(new File("workbook.xls"));
HSSFWorkbook workbook = new HSSFWorkbook(fileSystem.getRoot(), true);
Sheet sheet = workbook.getSheet("sheet");
/**
* cellNum:表示要冻结的列数, 从1开始
* rowNum:表示要冻结的行数，从1开始
* firstCellNum:表示被固定列右边第一列的列号，从0开始
* firstRollNum :表示被固定行下边第一列的行号，从0开始
* firstCellNum>=cellNum && firstRollNum >=cellNum
*/
sheet.createFreezePane(int cellNum,int rowNum,int firstCellNum,int firstRollNum);
try (OutputStream fileOut = new FileOutputStream("workbook.xls")) {
workbook.write(fileOut);
}
workbook.close();
fileSystem.close();