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jsp中文件下载的实现

2024-07-07 05:46:17   226人阅读

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-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();
		}
	}
}
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=http://www.mamicode.com/"/DownloadFile/upload/helloworld.jar">helloworld.jar
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=http://www.mamicode.com/"">>


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