2011级-csdn-java-张侃— Servlet监听器在开发中的应用案例
案例：显示登陆用户列表，并实现踢人功能。
登陆的jsp页面------------------------
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'login.jsp' starting page</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/LoginServlet" method="post">
用户名：
<input type="text" name="username"><br>
密 码：
<input type="text" name="password"><br>
<input type="submit" value="登陆">
</form>
</body>
</html>
处理登陆请求的servlet---------------------------
package com.hbsi.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.hbsi.domain.User;
public class LoginServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String username=request.getParameter("username");
String password=request.getParameter("password");
User user=new User();
user.setUsername(username);
user.setPassword(password);
request.getSession().setAttribute("user",user);
response.sendRedirect("/ListenerKicking/index.jsp");
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
显示登陆成功与否的jsp页面------------------
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'index.jsp' starting page</title>
</head>
<body>
欢迎您：${user.username} <br>
</body>
</html>
显示用户列表的jsp页面-----------------
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'userJsp.jsp' starting page</title>
</head>
<body>
当前在线用户为：
<br />
<c:forEach items="${map}" var="me">
<c:url value="/KickUserServlet" var="url">
<c:param name="username" value="${me.key}"></c:param>
</c:url>
${me.key}<a href="${url}">剔出去</a>
<br />
</c:forEach>
</body>
</html>
处理踢人请求的servlet-----------------------------
package com.hbsi.servlet;
import java.io.IOException;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class KickUserServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String username=request.getParameter("username");
username=new String(username.getBytes("iso8859-1"),"Utf-8");
Map map=(Map) this.getServletContext().getAttribute("map");
HttpSession session=(HttpSession) map.get(username);
if(session!=null){
session.invalidate();
map.remove(username);
}
request.getRequestDispatcher("/userJsp.jsp").forward(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
servlet监听器-------------
package com.hbsi.listener;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
import com.hbsi.domain.User;
public class SessionListener implements HttpSessionAttributeListener {
@Override
public void attributeAdded(HttpSessionBindingEvent se) {
Object obj=se.getValue();
if(obj instanceof User){
User user=(User) obj;
HttpSession session=se.getSession();
Map map=(Map) session.getServletContext().getAttribute("map");
if(map==null){
map=new HashMap();
session.getServletContext().setAttribute("map",map);
}
map.put(user.getUsername(),session);
}
}
@Override
public void attributeRemoved(HttpSessionBindingEvent se) {
}
@Override
public void attributeReplaced(HttpSessionBindingEvent se) {
// TODO Auto-generated method stub
}
}
实体类------------------------
package com.hbsi.domain;
public class User {
private String username;
private String password;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
处理乱码的过滤器----------------
package com.hbsi.filter; import java.io.IOException; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; public class CharseterEncodingFilter implements Filter { private FilterConfig config = null; private String defaultCharset = "UTF-8"; @Override public void destroy() { // TODO Auto-generated method stub } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { String charset = config.getInitParameter("charset"); if(charset==null){ charset = defaultCharset; } request.setCharacterEncoding(charset); response.setCharacterEncoding("UTF-8"); response.setContentType("text/html;charset="+charset); chain.doFilter(request, response); } @Override public void init(FilterConfig filterConfig) throws ServletException { this.config = filterConfig; } }
配置文件----------
<?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">
<filter>
<filter-name>CharseterEncodingFilter</filter-name>
<filter-class>com.hbsi.filter.CharseterEncodingFilter</filter-class>
<init-param>
<param-name>charset</param-name>
<param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>CharseterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<listener>
<listener-class>com.hbsi.listener.SessionListener</listener-class>
</listener>
<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>com.hbsi.servlet.LoginServlet</servlet-class>
</servlet>
<servlet>
<servlet-name>KickUserServlet</servlet-name>
<servlet-class>com.hbsi.servlet.KickUserServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/LoginServlet</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>KickUserServlet</servlet-name>
<url-pattern>/KickUserServlet</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
项目所导的包------------
