文件下载

servlet MoreDownloadServlet.java：

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
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;

import cn.itcast.util.FirxFoxUtil;


/**
 * 下载案例后台
 * @author Administrator
 *
 */
public class MoreDownloadServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 获取绝对路径
        String filepath = request.getParameter("filepath");
        filepath = new String(filepath.getBytes("ISO-8859-1"),"UTF-8");
        System.out.println("文件的绝对路径："+filepath);
        String filename = null;
        // 截取文件的名称
        int index = filepath.lastIndexOf("\");
        if(index != -1){
            filename = filepath.substring(index + 1);
        }
        
        // 先判断是什么浏览器
        String agent = request.getHeader("USER-AGENT");
        System.out.println(agent);
        // 判断当前是什么浏览器
        if(agent.contains("Firefox")){
            // 采用BASE64编码
            filename = FirxFoxUtil.base64EncodeFileName(filename);
        }else{
            // IE GOOGLE
            filename = URLEncoder.encode(filename, "UTF-8");
            // URL编码会空格编成+
            filename = filename.replace("+", " ");
        }
        
        // 创建file对象
        File file = new File(filepath);
        // 输入流
        InputStream in = new BufferedInputStream(new FileInputStream(file));
        // 设置两个响应头
        response.setContentType(this.getServletContext().getMimeType(filename));
        response.setHeader("Content-Disposition", "attachment;filename="+filename);
        // 一个流
        OutputStream os = response.getOutputStream();
        int b;
        while((b = in.read()) != -1){
            os.write(b);
        }
        os.close();
        in.close();
    }

}

util：

Base64Util.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import sun.misc.BASE64Encoder;

public class Base64Util {
    public static void main(String args[]) throws IOException {
        System.out.print("请输入用户名:");
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        String userName = in.readLine();
        System.out.print("请输入密码:");
        String password = in.readLine();
        BASE64Encoder encoder = new BASE64Encoder();
        System.out.println("编码后的用户名为:" + encoder.encode(userName.getBytes()));
        System.out.println("编码后的密码为:" + encoder.encode(password.getBytes()));
    }
}

FirxFoxUtil.java：

import java.io.UnsupportedEncodingException;

import sun.misc.BASE64Encoder;

public class FirxFoxUtil {
    
    public static String base64EncodeFileName(String fileName) {
        BASE64Encoder base64Encoder = new BASE64Encoder();
        try {
            return "=?UTF-8?B?"
                    + new String(base64Encoder.encode(fileName
                            .getBytes("UTF-8"))) + "?=";
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
            throw new RuntimeException(e);
        }
    }


}

jsp moredownload.jsp：

<%@page import="java.net.URLEncoder"%>
<%@page import="java.io.File"%>
<%@ 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="<%=basePath%>">
    
    <title>My JSP 'moredownload.jsp' starting page</title>
    
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->

  </head>
  
  <body>
  <%
      // 指定一个根目录
      String rootpath = "E:\downfile";
      // 创建File对象
      File rootfile = new File(rootpath);
      // 创建队列
      Queue<File> queue = new LinkedList<File>();
      // 把根目录入队
      queue.offer(rootfile);
      while(!queue.isEmpty()){
          // 先把根目录出队
          File file = queue.poll();
          File [] files = file.listFiles();
          // 循环遍历，拿到每一个file对象，操作file的判断是否是文件还是文件夹
          for(File f : files){
              if(f.isFile()){
                  // 文件
  %>
          <a href="/day22/moredownload?filepath=<%=URLEncoder.encode(f.getCanonicalPath(), "UTF-8")%>"><%=f.getName() %></a><br/>
  <%                
              }else{
                  //文件夹
                  queue.offer(f);
              }
          }
      }
  
   %>
  </body>
</html>