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小蚂蚁 发表于 2021-10-20 14:18:53

jsp文件下载功能实现代码

本文实例为大家分享了jsp实现文件下载功能的3种方法，供大家参考，具体内容如下
第一种、采用转发的方式：

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/1/10213.jpg";//即将下载的文件的相对路径
    String filedisplay = "10213.jpg";//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-stream
    response.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();
    }
}
}
二、通过输出流的方式：

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 {
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");

    String filedisplay = "helloworld.jpg";
    String filedownload = basePath + File.separator + "helloworld.jpg";
    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;
    int len = 0;
    while((len = bis.read(b)) != -1){
      bos.write(b,0,len);
    }
   
    bis.close();
    is.close();
    bos.close();
    os.close();
}
}


第三种、通过超链接的方式(注意不推荐，因为会暴露下载文件的位置)
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持CodeAE代码之家。

https://www.uoften.com/program/jsp/20180413/48280.html

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