黑马程序员技术交流社区

标题: 求高手指导 [打印本页]

作者: qq1175387339 时间: 2016-1-17 12:34
标题: 求高手指导
package com.message;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;

public class FileDownServlet extends HttpServlet {
private static final String CONTENT_TYPE = "text/html; charset=GBK";

//Initialize global variables
public void init() throws ServletException {
}

//Process the HTTP Get request
public void doGet(HttpServletRequest request, HttpServletResponse response) throws
         ServletException, IOException {
      response.setContentType(CONTENT_TYPE);
      //得到下载文件的名字
      //String filename=request.getParameter("filename");

      //解决中文乱码问题
      String filename=new String(request.getParameter("filename").getBytes("iso-8859-1"),"gbk");

      //创建file对象
      File file=new File("F://book//WebRoot//"+filename);

      //设置response的编码方式
      response.setContentType("application/x-msdownload");

      //写明要下载的文件的大小
      response.setContentLength((int)file.length());

      //设置附加文件名
   // response.setHeader("Content-Disposition","attachment;filename="+filename);

      //解决中文乱码
response.setHeader("Content-Disposition","attachment;filename="+new String

(filename.getBytes("gbk"),"iso-8859-1"));

      //读出文件到i/o流
      FileInputStream fis=new FileInputStream(file);
      BufferedInputStream buff=new BufferedInputStream(fis);

      byte [] b=new byte[1024];//相当于我们的缓存

      long k=0;//该值用于计算当前实际下载了多少字节

      //从response对象中得到输出流,准备下载

      OutputStream myout=response.getOutputStream();

      //开始循环下载

      while(k<file.length()){

         int j=buff.read(b,0,1024);
         k+=j;

         //将b中的数据写到客户端的内存
         myout.write(b,0,j);

      }

      //将写入到客户端的内存的数据,刷新到磁盘
      myout.flush();

}

//Process the HTTP Post request
public void doPost(HttpServletRequest request, HttpServletResponse response) throws
         ServletException, IOException {
      doGet(request, response);
}

//Clean up resources
public void destroy() {
}
}

//这是javabean写法，主要是实现和数据库连接的，如果没有连接数据库，就可直接不要这
package com;

public class MessageBean {
private String Message;

public String getMessage() {
  return Message;
}

public void setMessage(String message) {
  Message = message;
}
}

//HTML页面载入写发，也可连接数据库（案例代码也在）
<%@ page language="java" import="java.util.*,com.message.*" pageEncoding="gbk"%>
<jsp:directive.page import="com.MessageBean;"/>
<%
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 'book.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">


  </head>

  <body>

<%
  //Vector vv=(Vector)session.getAttribute("message");
  //for(int i=0;i<vv.size();i++){
// MessagesBean mb=(MessagesBean)vv.get(i);
// out.println("<tr>");
// out.println("<td>"+mb.getSender()+"</td>");
// out.println("<td>"+mb.getMess_time()+"</td>");
// out.println("<td>"+mb.getGeter()+"</td>");
// out.println("<td>"+mb.getMess_content()+"</td>");
String filename=null;
session.setAttribute("java.rar",filename);
//取得文件名
// filename=getFilepath().substring(mb.getFilepath().lastIndexOf("/")+1);
out.println("<td><a href=FileDownServlet?filename=java.rar>5.1下载书--java</a></td>");//java.rar这个可以改成变量
out.println("<td><a href=FileDownServlet?filename=dos.rar>dos视频教程</a></td>");
out.println("<td><a href=FileDownServlet?filename=常用DOS命令.rar>常用DOS命令</a></td>");
out.println("</tr>");
// }
  %>
  </body>
</html>

//这是web.xml配置文件，这很重要，不然，很难实现哦
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
  <servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>FileDownServlet</servlet-name>
<servlet-class>com.message.FileDownServlet</servlet-class>
  </servlet>

  <servlet-mapping>
<servlet-name>FileDownServlet</servlet-name>
<url-pattern>/FileDownServlet</url-pattern>
  </servlet-mapping>
</web-app>

作者: zhang洁 时间: 2016-1-27 17:53
完全看不懂，呜呜

作者: 1412864497 时间: 2016-1-27 23:30
顶顶顶！顶起来

作者: 酱油 时间: 2016-1-29 13:20
错误也贴出来啊，

欢迎光临黑马程序员技术交流社区 (http://bbs.itheima.com/)

黑马程序员IT技术论坛 X3.2