Servlet实现web站点文件下载功能示例，servletweb,1、首先创建一个Shar

Servlet实现web站点文件下载功能示例，servletweb,1、首先创建一个Shar

1、首先创建一个SharedFilesServlet用于返回一个文件分享界面

package com.hyman.view;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class SharedFilesServlet */public class SharedFilesServlet extends HttpServlet {    private static final long serialVersionUID = 1L;    /**     * @see HttpServlet#HttpServlet()     */    public SharedFilesServlet() {        super();        // TODO Auto-generated constructor stub    }    /**     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)     */    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        // TODO Auto-generated method stub        response.setContentType("text/html; charset=utf-8");         PrintWriter out = response.getWriter();        out.println("<script type='text/javascript' language='javascript'>"                + "function fileDown(obj){"                + "var resourceName = '';"                + "var buttonId = obj.getAttribute('id');"                + "var eleName = buttonId.substring(0,3) + 'File';"                            + "resourceName = document.getElementsByName(eleName)[0].value;"                + "var url = '/SharingSite/DownFileServlet?fileName=' + resourceName;"                + "window.location.href=url;"                + "}"                + "</script>");        out.println("<h1>文件共享网站</h1>");        out.println("mp3资源：<input type='text' name='mp3File' />&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<input type='submit' value ='点击下载' id='mp3Down' onclick='fileDown(this)' /><br/>");        out.println("avi资源：<input type='text' name='aviFile' />&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<input type='submit' value ='点击下载' id='aviDown' onclick='fileDown(this)' /><br/>");        out.println("jpg资源：<input type='text' name='jpgFile' />&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<input type='submit' value ='点击下载' id='jpgDown' onclick='fileDown(this)' /><br/>");        out.println("txt资源：<input type='text' name='txtFile' />&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<input type='submit' value ='点击下载' id='txtDown' onclick='fileDown(this)' /><br/>");    }    /**     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)     */    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        // TODO Auto-generated method stub        this.doGet(request, response);    }}

2、然后创建一个控制器，来判断是否盗链，以及处理文件下载逻辑：

package com.hyman.controller;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.io.OutputStream;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class DownFileServlet */public class DownFileServlet extends HttpServlet {    private static final long serialVersionUID = 1L;    /**     * @see HttpServlet#HttpServlet()     */    public DownFileServlet() {        super();        // TODO Auto-generated constructor stub    }    /**     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)     */    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        // TODO Auto-generated method stub        response.setContentType("text/html; charset=utf-8");        String referer = request.getHeader("Referer");        if (referer == null || !referer.startsWith("http://localhost:8080/SharingSite/")) {            response.sendRedirect("/SharingSite/AntiPirateLink");        } else {            String fileName = request.getParameter("fileName");            response.setHeader("Content-Disposition", "attachment; filename="+fileName);            String path = this.getServletContext().getRealPath("/resources/"+fileName);            FileInputStream fis = null;            OutputStream os = null;            try {                fis = new FileInputStream(new File(path));                byte buff[] = new byte[1024];                int len = 0;                os = response.getOutputStream();                while ((len = fis.read(buff)) > 0) {                    os.write(buff, 0, len);                }            } catch (Exception e) {                e.printStackTrace();                throw new RuntimeException();            } finally {                if (os != null) os.close();                if (fis != null) fis.close();            }        }    }    /**     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)     */    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        // TODO Auto-generated method stub        this.doGet(request, response);    }}

3、创建一个AntiPirateLink返回盗链提醒界面，并在10秒后自动刷新跳转到SharedFilesServlet

package com.hyman.view;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class AntiPirateLink */public class AntiPirateLink extends HttpServlet {    private static final long serialVersionUID = 1L;    /**     * @see HttpServlet#HttpServlet()     */    public AntiPirateLink() {        super();        // TODO Auto-generated constructor stub    }    /**     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)     */    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        // TODO Auto-generated method stub        response.setContentType("text/html; charset=utf-8");        PrintWriter out = response.getWriter();        out.println("<script type='text/javascript' language='javascript'>"                + "var i = 10;"                + "function showTime(){"                + "if(i > 0) {document.getElementById('time').innerHTML = '请不要盗链下载... ' + i +' 秒后自动跳转到下载首页...';"                + "i--;}"                + "}"                + "setInterval('showTime()',1000);"                + "</script>");        out.println("<span id='time'></span>");        response.setHeader("Refresh", "10; url=/SharingSite/SharedFilesServlet");    }    /**     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)     */    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        // TODO Auto-generated method stub        this.doGet(request, response);    }}

【分析】文件下载部分实现步骤： 【分析】文件下载部分实现步骤：

1、response.setHeader("Content-Disposition","attachment;filename="+fileName);在http回复消息头中的Content-Disposition中指明下文件的文件名；2、调用this.getServletContext().getRealPath("/resources/"+fileName);函数获取到文件的全路径；3、使用文件流FileInputStream将文件读入到服务器内存，重要要用到缓存处理，然后再调用response的getOutputStream()方法获得向客户端写文件的输出文件流；

来自：http://www.cnblogs.com/page-of-Hyman/p/4321523.html