jsp中文件下载的实现

方式一：采用RequestDispatcher进行

1. package cn.jbit.download.servlet;  
2.   
3. import java.io.IOException;  
4.   
5. import javax.servlet.RequestDispatcher;  
6. import javax.servlet.ServletException;  
7. import javax.servlet.http.HttpServlet;  
8. import javax.servlet.http.HttpServletRequest;  
9. import javax.servlet.http.HttpServletResponse;  
10.   
11. public class DownloadServlet extends HttpServlet {  
12.   
13.     private static final long serialVersionUID = 6765085208899952414L;  
14.   
15.     public void doGet(HttpServletRequest request, HttpServletResponse response)  
16.             throws ServletException, IOException {  
17.         doPost(request, response);  
18.     }  
19.   
20.     public void doPost(HttpServletRequest request, HttpServletResponse response)  
21.             throws ServletException, IOException {  
22.         String filedownload = "/upload/helloworld.jar";//即将下载的文件的相对路径  
23.         String filedisplay = "helloworld.jar";//下载文件时显示的文件保存名称  
24.         response.setContentType("application/x-download");//设置为下载application/x-download  
25.         //response.setContentType("application/x-msdownload");//设置为下载application/x-msdownload  
26.         //response.setContentType("application/octet-stream");//设置为下载application/octet-stream  
27.         response.addHeader("Content-Disposition", "attachment;filename="  
28.                 + filedisplay);  
29.           
30.         try {  
31.             RequestDispatcher rd = request.getRequestDispatcher(filedownload);  
32.             if(rd != null)  
33.             {  
34.                 rd.forward(request,response);  
35.             }  
36.             response.flushBuffer();  
37.         } catch (Exception e) {  
38.             e.printStackTrace();  
39.         }  
40.     }  
41. }  

1. package cn.jbit.download.servlet;  
2.   
3. import java.io.BufferedInputStream;  
4. import java.io.BufferedOutputStream;  
5. import java.io.File;  
6. import java.io.FileInputStream;  
7. import java.io.IOException;  
8. import java.io.InputStream;  
9. import java.io.OutputStream;  
10.   
11. import javax.servlet.ServletException;  
12. import javax.servlet.http.HttpServlet;  
13. import javax.servlet.http.HttpServletRequest;  
14. import javax.servlet.http.HttpServletResponse;  
15.   
16. public class DownloadOfIOServlet extends HttpServlet {  
17.   
18.     private static final long serialVersionUID = 6765085208899952414L;  
19.   
20.     public void doGet(HttpServletRequest request, HttpServletResponse response)  
21.             throws ServletException, IOException {  
22.         doPost(request, response);  
23.     }  
24.       
25.     public void doPost(HttpServletRequest request, HttpServletResponse response)  
26.             throws ServletException, IOException {  
27.         String basePath = request.getSession().getServletContext().getRealPath("/upload");  
28.         //System.out.println(basePath);  
29.         String filedisplay = "helloworld.jar";  
30.         String filedownload = basePath + File.separator + "helloworld.jar";  
31.         System.out.println("----------------------"+filedownload);  
32.         response.setContentType("applicaiton/x-download");  
33.         response.addHeader("Content-Disposition", "attachment;filename="+filedisplay);  
34.           
35.         InputStream is = null;  
36.         OutputStream os = null;  
37.         BufferedInputStream bis = null;  
38.         BufferedOutputStream bos = null;  
39.           
40.         is = new FileInputStream(new File(filedownload));  
41.         bis = new BufferedInputStream(is);  
42.         os = response.getOutputStream();  
43.         bos = new BufferedOutputStream(os);  
44.           
45.         byte[] b = new byte[1024];  
46.         int len = 0;  
47.         while((len = bis.read(b)) != -1){  
48.             bos.write(b,0,len);  
49.         }  
50.           
51.         bis.close();  
52.         is.close();  
53.         bos.close();  
54.         os.close();  
55.     }  
56. }  

1. <a href="/DownloadFile/upload/helloworld.jar">helloworld.jara>  

1. <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>  
2. <%  
3. String path = request.getContextPath();  
4. String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";  
5. %>  
6.   
7. >  
8. <html>  
9.   <head>  
10.     <base href="<%=basePath%>">  
11.     <title>My JSP 'download.jsp' starting pagetitle>  
12.     <meta http-equiv="pragma" content="no-cache">  
13.     <meta http-equiv="cache-control" content="no-cache">  
14.     <meta http-equiv="expires" content="0">      
15.   head>  
16.     
17.   <body>  
18.     下载1<a href="/DownloadFile/upload/helloworld.jar">helloworld.jara><br/>  
19.     下载2<a href="/DownloadFile/servlet/downloadServlet">helloworld.jara><br/>  
20.     下载3<a href="/DownloadFile/servlet/downloadOfIOServlet">helloworld.jara><br/>  
21.     下载4<a href="/DownloadFile/download/filedownload.action">helloworld.jara><br/>  
22.   body>  
23. html>  

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