用JAVA代码来导出EXCEL

有些情况下我们需要将数据导出到excel中

例子：根据一个班级ID 来导出全班学生的成绩

两个实体类

班级实体类

Class.java

public class Class {
private int classId;//班级ID
private String className;//班级名称
。。。

}
}

学生实体类

Student.java

public class Student {
private int stuId;//学号
private String stuName;//姓名
private double scode;//得分
private String classID;//班级ID

。。。

}

导出excel方法（这里是struts框架的Action中的方法可以直接调用保存excel）

public ActionForward exportExcel(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {
//假设掉用方法时传入班级编号

   String classId= request.getParameter("id");
   Class class= classManager.getClassById(classId);//此方法自行实现s
   if (class== null)
    return null;
   List<Student> list = stuManager .getStuListByClassId(classId);//此方法自行实现

   String[] columnHeads = { "学号", "姓名", "得分"};
   int columnsize = columnHeads.length, rowsize = list.size(), rowindex = 0;
   // 创建一个HSSFWorbook对象s
   HSSFWorkbook hWorkbook = new HSSFWorkbook();

   // 创建一个HSSFSheet对象（相当于作业本的某一页）
   HSSFSheet hSheet = hWorkbook.createSheet();
   // 创建行(此行作为头)----------------创建头开始
   HSSFRow hRow = hSheet.createRow(rowindex++);
   //创建单元格（第一（0）个）

HSSFCell hCell = hRow.createCell((short) 0);

//设置字符集
hCell.setEncoding(HSSFCell.ENCODING_UTF_16);

//调用getCellStyle（）方法获得一个格式对象
HSSFCellStyle cellStyle = getCellStyle(hWorkbook, (short) 320,(short) 700);

//将上面获得的格式对象给对应单元格

hCell.setCellStyle(cellStyle);

hCell.setCellValue("YYS学校"+class.getClassName()+"班成绩单");

   //批量创建单元格-----------到后面合并单元格
   for (int i = 1; i < columnsize; i++) {
    hCell = hRow.createCell((short) i);
    hCell.setCellStyle(cellStyle);
   }

// 创建行----------------创建头结束

//创建表头（学号姓名得分）

   hRow = hSheet.createRow(rowindex++);
   cellStyle = getCellStyle(hWorkbook, (short) 220, (short) 600);
   for (int i = 0; i < columnsize; i++) {
    hCell = hRow.createCell((short) i);
    hCell.setEncoding(HSSFCell.ENCODING_UTF_16);
    hCell.setCellValue(columnHeads[i]);
    hCell.setCellStyle(cellStyle);
   }

//遍历所有学生
cellStyle = getCellStyle(hWorkbook, (short) 220, (short) 500);//设置单元格格式

   for (int i = 0, j = 0; i < rowsize; i++, j = 0) {
    hRow = hSheet.createRow(rowindex++);
    Student stu = list.get(i);
    // 学号
    hCell = hRow.createCell((short) j);
    hCell.setEncoding(HSSFCell.ENCODING_UTF_16);
    hCell.setCellValue(stu.getStuId());
    hCell.setCellStyle(cellStyle);
    hSheet.setColumnWidth((short) j++, (short) 2000);

    // 姓名
    hCell = hRow.createCell((short) j);
    hCell.setEncoding(HSSFCell.ENCODING_UTF_16);
    hCell.setCellValue(stu.getStuName());
    hCell.setCellStyle(cellStyle);
    hSheet.setColumnWidth((short) j++, (short) 3000);

// 得分

    hCell = hRow.createCell((short) j);
    hCell.setEncoding(HSSFCell.ENCODING_UTF_16);
    hCell.setCellValue(stu.getScode());
    hCell.setCellStyle(cellStyle);
    hSheet.setColumnWidth((short) j++, (short) 3000);

}

   //合并单元格四个参数的意思是（X1，Y1，X2，Y2）
   hSheet.addMergedRegion(new Region(0, (short) 0, 0,
     (short) (columnsize - 1)));

//固定表头（前一个参数代表列，后一个参数单表行）
hSheet.createFreezePane(0, 1);

response.setContentType("application/x-download");

String filename = URLEncoder.encode(class.getClassName()+ ".xls", "UTF-8");

   response.addHeader("Content-Disposition", "attachment;filename="+ filename);
   response.setContentType("application/msexcel"); // 定义输出类型
   response.setContentType("UTF-8");
   hWorkbook.write(response.getOutputStream());
   response.getOutputStream().flush();
   response.getOutputStream().close();
}
return null;
}

//设置样式方法

public HSSFCellStyle getCellStyle(HSSFWorkbook hWorkbook, short fontHeight,
short boldWeight) {
HSSFCellStyle cellStyle = hWorkbook.createCellStyle();
HSSFFont font = hWorkbook.createFont();
cellStyle = hWorkbook.createCellStyle();
cellStyle.setBorderBottom(HSSFCellStyle.BORDER_THIN);
cellStyle.setBorderLeft(HSSFCellStyle.BORDER_THIN);
cellStyle.setBorderRight(HSSFCellStyle.BORDER_THIN);
cellStyle.setBorderTop(HSSFCellStyle.BORDER_THIN);
cellStyle.setTopBorderColor(HSSFColor.BLACK.index);
cellStyle.setLeftBorderColor(HSSFColor.BLACK.index);
cellStyle.setRightBorderColor(HSSFColor.BLACK.index);
cellStyle.setBottomBorderColor(HSSFColor.BLACK.index);
font = hWorkbook.createFont();
font.setFontHeight(fontHeight);
font.setBoldweight(boldWeight);
font.setFontName("宋体");
cellStyle.setFont(font);
cellStyle.setWrapText(true);
cellStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);
cellStyle.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER)

return cellStyle;
}

摘自 xuliangwen的专栏

补充：软件开发 , Java ,