使用POI进行Excel高效导入导出操作详解

1.创建工作簿 (WORKBOOK)
    HSSFWorkbook wb = new HSSFWorkbook();
    FileOutputStream fileOut = new FileOutputStream("workbook.xls");
    wb.write(fileOut);
    fileOut.close();
2.创建工作表（SHEET）
    HSSFWorkbook wb = new HSSFWorkbook();
    HSSFSheet sheet1 = wb.createSheet("new sheet");
    HSSFSheet sheet2 = wb.createSheet("second sheet");
    FileOutputStream fileOut = new FileOutputStream("workbook.xls");
    wb.write(fileOut);
    fileOut.close();
3.创建单元格(CELL)
    HSSFWorkbook wb = new HSSFWorkbook();
    HSSFSheet sheet = wb.createSheet("new sheet");
    // Create a row and put some cells in it. Rows are 0 based.
    HSSFRow row = sheet.createRow((short)0);
    // Create a cell and put a value in it.
    HSSFCell cell = row.createCell((short)0);
    cell.setCellValue(1);
    // Or do it on one line.
    row.createCell((short)1).setCellValue(1.2);
    row.createCell((short)2).setCellValue("This is a string");
    row.createCell((short)3).setCellValue(true);
    // Write the output to a file
    FileOutputStream fileOut = new FileOutputStream("workbook.xls");
    wb.write(fileOut);
    fileOut.close();
4.创建指定单元格式的单元格
    HSSFWorkbook wb = new HSSFWorkbook();

    HSSFSheet sheet = wb.createSheet("new sheet");
    // Create a row and put some cells in it. Rows are 0 based.
    HSSFRow row = sheet.createRow((short)0);
    // Create a cell and put a date value in it.  The first cell is not styled
    // as a date.
    HSSFCell cell = row.createCell((short)0);
    cell.setCellValue(new Date());
    // we style the second cell as a date (and time).  It is important to
    // create a new cell style from the workbook otherwise you can end up
    // modifying the built in style and effecting not only this cell but other cells.
    HSSFCellStyle cellStyle = wb.createCellStyle();
    cellStyle.setDataFormat(HSSFDataFormat.getBuiltinFormat("m/d/yy h:mm"));
    cell = row.createCell((short)1);
    cell.setCellValue(new Date());
    cell.setCellStyle(cellStyle);
    // Write the output to a file
    FileOutputStream fileOut = new FileOutputStream("workbook.xls");
    wb.write(fileOut);
    fileOut.close();
5. 单元格的不同格式
    HSSFWorkbook wb = new HSSFWorkbook();
    HSSFSheet sheet = wb.createSheet("new sheet");
    HSSFRow row = sheet.createRow((short)2);
    row.createCell((short) 0).setCellValue(1.1);
    row.createCell((short) 1).setCellValue(new Date());
    row.createCell((short) 2).setCellValue("a string");
    row.createCell((short) 3).setCellValue(true);
    row.createCell((short) 4).setCellType(HSSFCell.CELL_TYPE_ERROR);
    // Write the output to a file
    FileOutputStream fileOut = new FileOutputStream("workbook.xls");