Java Web学习总结-文件下载

 <servlet>
       <servlet-name>DownLoadServlet</servlet-name>
       <servlet-class>com.thinkplatform.controller.DownLoadServlet</servlet-class>
  </servlet>
  
  <servlet-mapping>
       <servlet-name>DownLoadServlet</servlet-name>
       <url-pattern>/servlet/DownLoadServlet</url-pattern>
  </servlet-mapping> 

<td style="width:80px;">
    <c:url value="/servlet/DownLoadServlet" var="downurl">
        <c:param name="path" value="${item.path}"></c:param>
        <c:param name="fileName" value="${item.id}"></c:param>
    </c:url>
    <a href="${downurl}">下载</a>
</td>

package com.thinkplatform.controller;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
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 {
        //得到要下载的文件名
        String fileName = request.getParameter("fileName");  
        //得到要下载的文件的路径
        String path = request.getParameter("path");  

        //得到要下载的文件
        File file = new File(path + "\\" + fileName);
        //如果文件不存在
        if(!file.exists()){
            request.setAttribute("message", "您要下载的资源已被删除！！");
            return;
        }
       
        //设置响应头，控制浏览器下载该文件
        response.setHeader("content-disposition", "attachment;filename=" + URLEncoder.encode(fileName, "UTF-8"));
        //读取要下载的文件，保存到文件输入流
        FileInputStream in = new FileInputStream(path + "\\" + fileName);
        //创建输出流
        OutputStream out = response.getOutputStream();
        //创建缓冲区
        byte buffer[] = new byte[1024];
        int len = 0;
        //循环将输入流中的内容读取到缓冲区当中
        while((len=in.read(buffer))>0){
            //输出缓冲区的内容到浏览器，实现文件下载
            out.write(buffer, 0, len);
        }
        //关闭文件输入流
        in.close();
        //关闭输出流
        out.close();
    
    }
         

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