java POI操作 excel ，代码如何修改，每执行一次，添加1行，而不覆盖以前的数据

lakerspf_135269danzi 2014-09-19 10:39:50

package com.tzy.exceldemo;

import java.io.FileOutputStream;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.List;

import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;

public class CreateSimpleExcelToDisk
{
/**
* @功能：手工构建一个简单格式的Excel
*/
private static List<Student> getStudent() throws Exception
{
List list = new ArrayList();
SimpleDateFormat df = new SimpleDateFormat("yyyy-mm-dd");

Student user1 = new Student(4, "张三fjj", 16, df.parse("1997-03-12"));
Student user2 = new Student(5, "李四1", 17, df.parse("1996-08-12"));
Student user3 = new Student(6, "王五", 26, df.parse("1985-11-12"));
list.add(user1);
list.add(user2);
list.add(user3);

return list;
}

public static void main(String[] args) throws Exception
{
// 第一步，创建一个webbook，对应一个Excel文件
HSSFWorkbook wb = new HSSFWorkbook();
// 第二步，在webbook中添加一个sheet,对应Excel文件中的sheet
HSSFSheet sheet = wb.createSheet("学生表学生表学生表");
// 第三步，在sheet中添加表头第0行,注意老版本poi对Excel的行数列数有限制short
HSSFRow row = sheet.createRow((int) 0);
// 第四步，创建单元格，并设置值表头设置表头居中
HSSFCellStyle style = wb.createCellStyle();
style.setAlignment(HSSFCellStyle.ALIGN_CENTER); // 创建一个居中格式

HSSFCell cell = row.createCell((short) 0);
cell.setCellValue("学号");
cell.setCellStyle(style);
cell = row.createCell((short) 1);
cell.setCellValue("姓名");
cell.setCellStyle(style);
cell = row.createCell((short) 2);
cell.setCellValue("年龄");
cell.setCellStyle(style);
cell = row.createCell((short) 3);
cell.setCellValue("生日");
cell.setCellStyle(style);

// 第五步，写入实体数据实际应用中这些数据从数据库得到，
List list = CreateSimpleExcelToDisk.getStudent();

for (int i = 0; i < list.size(); i++)
{
row = sheet.createRow( i + 1);
Student stu = (Student) list.get(i);
// 第四步，创建单元格，并设置值
row.createCell((short) 0).setCellValue((double) stu.getId());
row.createCell((short) 1).setCellValue(stu.getName());
row.createCell((short) 2).setCellValue((double) stu.getAge());
cell = row.createCell((short) 3);
cell.setCellValue(new SimpleDateFormat("yyyy-mm-dd").format(stu
.getBirth()));
}
// 第六步，将文件存到指定位置
try
{
FileOutputStream fout = new FileOutputStream("c:/students.xls",true);
wb.write(fout);
fout.close();
}
catch (Exception e)
{
e.printStackTrace();
}
}
}

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