jsp中文件下载的实现

来源：互联网发布：机械研发知乎编辑：程序博客网时间：2024/05/17 20:41

方式一：采用RequestDispatcher进行

package cn.jbit.download.servlet;import java.io.IOException;import javax.servlet.RequestDispatcher;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class DownloadServlet extends HttpServlet {private static final long serialVersionUID = 6765085208899952414L;public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {String filedownload = "/upload/helloworld.jar";//即将下载的文件的相对路径String filedisplay = "helloworld.jar";//下载文件时显示的文件保存名称response.setContentType("application/x-download");//设置为下载application/x-download//response.setContentType("application/x-msdownload");//设置为下载application/x-msdownload//response.setContentType("application/octet-stream");//设置为下载application/octet-streamresponse.addHeader("Content-Disposition", "attachment;filename="+ filedisplay);try {RequestDispatcher rd = request.getRequestDispatcher(filedownload);if(rd != null){rd.forward(request,response);}response.flushBuffer();} catch (Exception e) {e.printStackTrace();}}}

方式二：采用文件流输出的方式下载

package cn.jbit.download.servlet;import java.io.BufferedInputStream;import java.io.BufferedOutputStream;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class DownloadOfIOServlet extends HttpServlet {private static final long serialVersionUID = 6765085208899952414L;public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doPost(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {String basePath = request.getSession().getServletContext().getRealPath("/upload");//System.out.println(basePath);String filedisplay = "helloworld.jar";String filedownload = basePath + File.separator + "helloworld.jar";System.out.println("----------------------"+filedownload);response.setContentType("applicaiton/x-download");response.addHeader("Content-Disposition", "attachment;filename="+filedisplay);InputStream is = null;OutputStream os = null;BufferedInputStream bis = null;BufferedOutputStream bos = null;is = new FileInputStream(new File(filedownload));bis = new BufferedInputStream(is);os = response.getOutputStream();bos = new BufferedOutputStream(os);byte[] b = new byte[1024];int len = 0;while((len = bis.read(b)) != -1){bos.write(b,0,len);}bis.close();is.close();bos.close();os.close();}}

方式三：网页上做超级链接(不推荐使用，样服务器上的目录资源会直接暴露给最终用户)

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

jsp页面代码：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">    <title>My JSP 'download.jsp' starting page</title><meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0">      </head>    <body>  下载1<a href="/DownloadFile/upload/helloworld.jar">helloworld.jar</a><br/>  下载2<a href="/DownloadFile/servlet/downloadServlet">helloworld.jar</a><br/>  下载3<a href="/DownloadFile/servlet/downloadOfIOServlet">helloworld.jar</a><br/>  下载4<a href="/DownloadFile/download/filedownload.action">helloworld.jar</a><br/>  </body></html>

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