首先导入依赖

 <dependencies>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>3.9</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>3.9</version>
        </dependency>

        <dependency>
            <groupId>joda-time</groupId>
            <artifactId>joda-time</artifactId>
            <version>2.10.1</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
    </dependencies>

03版本xls比07版本xlsx的容量大，对应的工作类也不同

分别有:工作簿，工作表，行，列

生成03版本

  String PATH="D:\\";
    @Test
    public void testWrite03() throws Exception {
        //1.创建一个工作簿
        Workbook workbook=new HSSFWorkbook();
        //2.创建一个工作表
        Sheet sheet=workbook.createSheet("sheet1");
        //3.创建一个行
        Row row1=sheet.createRow(0);
        //4.创建一个单元格
        Cell cell11=row1.createCell(0);
        cell11.setCellValue("11");
        Cell cell12=row1.createCell(1);
        cell12.setCellValue("12");
        //第二行
        Row row2=sheet.createRow(1);

        Cell cell21=row2.createCell(0);
        cell21.setCellValue("21");
        Cell cell22=row2.createCell(1);
        cell22.setCellValue("22");

        FileOutputStream fileOutputStream = new FileOutputStream(PATH + "xxx.xls");
        workbook.write(fileOutputStream);
        fileOutputStream.close();
        System.out.println("生成完毕");
    }

生成07版本

 @Test
    public void testWrite07() throws Exception {
        //1.创建一个工作簿
        Workbook workbook=new XSSFWorkbook();
        //2.创建一个工作表
        Sheet sheet=workbook.createSheet("sheet1");
        //3.创建一个行
        Row row1=sheet.createRow(0);
        //4.创建一个单元格
        Cell cell11=row1.createCell(0);
        cell11.setCellValue("11");
        Cell cell12=row1.createCell(1);
        cell12.setCellValue("12");
        //第二行
        Row row2=sheet.createRow(1);

        Cell cell21=row2.createCell(0);
        cell21.setCellValue("21");
        Cell cell22=row2.createCell(1);
        cell22.setCellValue("22");

        FileOutputStream fileOutputStream = new FileOutputStream(PATH + "xxx.xlsx");
        workbook.write(fileOutputStream);
        fileOutputStream.close();
        System.out.println("生成完毕");
    }