使用POI生成excel,然后直接生成流文件,前台页面直接弹出下载窗口,不需要先生成excel文本再下载,省时省力
Apache POI是Apache软件基金会的开放源码函式库,POI提供API给Java程式对Microsoft Office格式档案读和写的功能。 .NET的开发人员则可以利用NPOI (POI for .NET) 来存取 POI 的功能。
poi导出excel基本步骤
第一步:引入所需的jar在工程项目lib目录下。
第二步:在点击导出页面设置一个事件触发servlet读出事先保存好的xsl文件;
<script type="text/javascript" charset="UTF-8">
function excel(){
window.location="exportExcel"; //“exportExcel”是一个servlet地址
}
</script>
<input type="button" value="导出excel" onclick="excel()">
第三步:实现servlet
package com.zust.servlet;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.zust.excel.*;
import com.zust.paper.Paper;
public class exportExcel extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//获得项目服务器根路径
String path = request.getSession().getServletContext().getRealPath("");
//把所有的路径的单斜杠替换成双斜杠
path = path.replace("\\","//");
gradesXLS xls = new gradesXLS(path);
List<Paper> list = (List<Paper>) request.getSession().getAttribute("paperLit");
Boolean flag = xls.CreateExcel(list);
OutputStream o = response.getOutputStream();
byte b[] = new byte[1024];
// the file to download.
File fileLoad = new File(path,"grades.xls");
// the dialogbox of download file.
response.setHeader("Content-disposition", "attachment;filename="+ "grades.xls");
// set the MIME type.
response.setContentType("application/vnd.ms-excel");
// get the file length.
long fileLength = fileLoad.length();
String length = String.valueOf(fileLength);
response.setHeader("Content_Length", length);
// download the file.
FileInputStream in = new FileInputStream(fileLoad);
int n = 0;
while ((n = in.read(b)) != -1) {
o.write(b, 0, n);
}
}
}
第四部:servlet调用的方法:xls.CreateExcel(list);
package com.zust.excel;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.List;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import com.zust.paper.Paper;
public class gradesXLS {
private String path;
//构造函数获取保存excel的路径
public gradesXLS(String path){
this.path = path;
}
public Boolean CreateExcel(List paperList) {
Boolean flag = true;
// 创建一个工作簿
HSSFWorkbook workBook = new HSSFWorkbook();
// 创建一个工作表,名为:第一页
HSSFSheet sheet = workBook.createSheet("成绩表");
// 设置单元格的宽度(0:表示第一行的第一个单元格,1:第一行的第二个单元格)
sheet.setColumnWidth((short) 0, 3500);
sheet.setColumnWidth((short) 1, 5000);
sheet.setColumnWidth((short) 2, 5000);
// 创建一个单元格,从0开始
HSSFRow row = sheet.createRow((short) 0);
// 构造一个数组设置第一行之后的单元格
HSSFCell cell[] = new HSSFCell[5];
for (int i = 0; i < 5; i++) {
cell[i] = row.createCell(i);
}
cell[0].setCellValue("用户名");
cell[1].setCellValue("开始时间");
cell[2].setCellValue("结束时间");
cell[3].setCellValue("集体编号");
cell[4].setCellValue("总分");
// 获得从数据库中查询出来的数据
if (paperList != null && paperList.size() > 0) {
// 循环list中的数据
for (int i = 0; i < paperList.size(); i++) {
Paper p = (Paper) paperList.get(i);
HSSFRow dataRow = sheet.createRow(i + 1);
HSSFCell data[] = new HSSFCell[5];
for (int j = 0; j < 5; j++) {
data[j] = dataRow.createCell(j);
}
data[0].setCellValue(p.getUsername());
data[1].setCellValue(p.getStarttime());
data[2].setCellValue(p.getEndtime());
if(p.getGroupno()!=-1){
data[3].setCellValue(p.getGroupno());
}else{
data[3].setCellValue("无");
}
data[4].setCellValue(p.getTotal());
try {
// 输出成XLS文件
File file = new File(path);
FileOutputStream fos = new FileOutputStream(file+"\\grades.xls");
// 写入数据,并关闭文件
workBook.write(fos);
fos.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
flag = false;
} catch (IOException e) {
e.printStackTrace();
flag = false;
}
}
}
return flag;
}
}