servlet实现文件下载功能
第二步：写servlet（DownloadServlet.java）
packagecom.example.servlet;
importjava.io.File;
importjava.io.IOException;
importjava.io.InputStream;
importjava.io.OutputStream;
importjavax.servlet.ServletException;
importjavax.servlet.http.HttpServlet;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;
/**
* Servlet implementation classDownloadServlet
*/
publicclass DownloadServlet extends HttpServlet {
privatestaticfinallongserialVersionUID = 1L;
/**
* @see HttpServlet#doGet(HttpServletRequestrequest, HttpServletResponse response)
*/
protectedvoiddoGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODOAuto-generated method stub
response.setContentType("text/html;charset=utf-8");
//通知浏览器下载的方式打开
response.addHeader("Content-Type", "application/octet-stream"); // 限制类型
String s1="我爱java.png";
String s2 = new String(s1.getBytes("GBK"),"ISO-8859-1");//解决乱码
response.addHeader("Content-Disposition", "attachment;filename="+s2);// 下载后的文件名
//通过文件流读取文件
File file= new File("/File/11.jpg");
InputStreamin=getServletContext().getResourceAsStream(file.toString());
//获取response对象的输出流
OutputStreamout=response.getOutputStream();
byte[] buffer =newbyte[1024];
int len;
while((len =in.read(buffer)) !=-1){
out.write(buffer,0,len);
}
in.close();
out.close();
}
/**
* @see HttpServlet#doPost(HttpServletRequestrequest, HttpServletResponse response)
*/
protectedvoiddoPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODOAuto-generated method stub
doGet(request, response);
}
}
第三步：配置web.xml
<?xml version="1.0"encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<display-name></display-name>
<servlet>
<servlet-name>DownloadServlet</servlet-name>
<servlet-class>com.example.servlet.DownloadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>DownloadServlet</servlet-name>
<url-pattern>/DownloadServlet</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
第四步：编写jsp页面（index.jsp）
<%@ page language="java" import="java.util.*"pageEncoding="UTF-8"%>
<%
Stringpath = request.getContextPath();
StringbasePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTDHTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'download.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>
<a href="DownloadServlet">
文件下载
</a>
</body>
</html>
第五步：Tomcat部署项目！运行下载！
