webapp项目的结构如下图：
download.html文件的内容如下：
<!DOCTYPE html><html><head><meta charset="UTF-8"><title>Insert title here</title></head><body> <h1>资源下载:</h1> <p> 单纯地使用a标签时，只有浏览器不能解析的文件才会是下载，否则将被浏览器直接解析。</p> <a href="/WEB/resource/a.mp3" rel="external nofollow" >a.mp3</a><br> <a href="/WEB/resource/a.exe" rel="external nofollow" >a.exe</a><br> <a href="/WEB/resource/a.txt" rel="external nofollow" >a.txt</a><br> <a href="/WEB/resource/a.xlsx" rel="external nofollow" >a.xlsx</a><br> <a href="/WEB/resource/a.png" rel="external nofollow" >a.png</a><br> <p>因此，使用a标签结合servlet的response指示浏览器不解析这些待下载文件</p> <a href="/WEB/download?filename=a.mp3" rel="external nofollow" >a.mp3</a><br> <a href="/WEB/download?filename=a.exe" rel="external nofollow" >a.exe</a><br> <a href="/WEB/download?filename=a.txt" rel="external nofollow" >a.txt</a><br> <a href="/WEB/download?filename=a.xlsx" rel="external nofollow" >a.xlsx</a><br> <a href="/WEB/download?filename=a.png" rel="external nofollow" >a.png</a><br></body></html>
负责处理下载的Servlet――download.java文件的内容如下：
package com.download.servlet;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStream;import javax.servlet.ServletException;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class Download */public class Download extends HttpServlet { private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1.获取请求下载的文件名 String filename = request.getParameter("filename"); //2.获取文件的文件系统路径 String filePath = request.getServletContext().getRealPath("resource/"+filename); //3.设置响应头，提示浏览器不要解析响应的文件数据，而是以附件(attachment)的形式解析，即下载功能 response.setContentType(this.getServletContext().getMimeType(filename)); response.setHeader("Content-Disposition", "attachment;filename="+filename); //4.读取文件的 输入流，以及响应的输出流，并将数据输出给客户端 InputStream in = new FileInputStream(filePath); ServletOutputStream out = response.getOutputStream(); int len = 0; byte[] buf = new byte[1024]; while((len=in.read(buf))!=-1) { out.write(buf, 0, len); } in.close(); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); }}在浏览器地址栏中输入http://localhost:8080/DownloadServlet/download.html。
以上这篇java web response提供文件下载功能的实例讲解就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持武林网。