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文件下载

2024-11-19 21:53:39   204人阅读

最重要的两点是设置响应头

1、设置contextType 响应头：通知客户端这是个下载文件

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

2、设置content=Disposition 响应头：通知浏览器不再由自己自行处理要下载的文件，而是由客户自己下载

　　response.setHeader("content-Disposition", "attachment;filename=" + URLEncoder.encode(fileName, "utf-8"));

jsp页面

<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%>
<%
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 ‘index.jsp‘ starting page</title>
  </head>
  
  <body>
      <a href="downLoadServlet">Study download</a>
  </body>
</html>

servlet

package com.future.demo;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.URLEncoder;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class DownLoadServlet extends HttpServlet {

    
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //设置contextType 响应头：通知客户端这是个下载文件
        response.setContentType("application/x-msdownload");
        
        //获取要下载的文件名字
        String fileName = "文件下载.txt";
        
        //设置content=Disposition 响应头：通知浏览器不再由自己自行处理要下载的文件，而是由客户自己下载
        response.setHeader("content-Disposition", "attachment;filename=" + URLEncoder.encode(fileName, "utf-8"));
        
        OutputStream os = response.getOutputStream();//不需要主动关流，是要用户自动处理的
        
        //要下载的文件
        InputStream is = new FileInputStream("C:\\Users\\Administrator\\Desktop\\ms.txt");
        int len = 0;
        byte[] buffer = new byte[1024];
        while((len=is.read(buffer))!=-1){
            os.write(buffer, 0, len);
        }
        is.close();
        //os.close();
    }

    
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
            doGet(request, response);
    }
}

 

文件下载


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