LoginServlet登录页面：
package com.tanzhou.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.tanzhou.util.User;
import com.tanzhou.util.UserList;
public class LoginServlet extends HttpServlet {
public LoginServlet() {
super();
}
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request,response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
String name = getNewString(request.getParameter("username"));
String pass = request.getParameter("userpass");
if(name==null || "".equals(name)){
response.sendRedirect("/OnlineUserDemo/login.html");
return ;
}else{
// 讲登录的用户名和密码保存到session中
HttpSession session = request.getSession(true);
// 保存对象到session
User user = (User)session.getAttribute("user");
if(user==null || !name.equals(user.getName())){
user = new User(name);
session.setAttribute("user", user);
}
}
PrintWriter out = response.getWriter();
out.println("欢迎用户："+name+"登录"+"<br/>");
out.println("<hr>"+"在线人数列表："+"<br/>");
UserList ul = UserList.getInstance();
/**
* Enumeration(列举)
*/
Enumeration<String> enums = ul.getUserList();
int i = 0;
while(enums.hasMoreElements()){
out.println(enums.nextElement()); // 遍历出来的用户信息
out.println(" ");
if((++i%8)==0){
out.println("<br>");
}
}
out.println("<hr>");
out.println("<br>"+"在线人数："+ul.getUserCount());
out.println("<br>"+"<a href='/OnlineUserDemo/servlet/OutServlet'>退出登录</a>");
out.flush();
out.close();
}
public void init() throws ServletException {
}
/**
* 编码集处理
* @param str
* @return
* @throws UnsupportedEncodingException
*/
public static String getNewString(String str) throws UnsupportedEncodingException
{
return new String(str.getBytes("ISO-8859-1"),"UTF-8");
}
}
OutServlet退出页面：
package com.tanzhou.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.tanzhou.util.User;
public class OutServlet extends HttpServlet {
/**
* Constructor of the object.
*/
public OutServlet() {
super();
}
/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request,response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
HttpSession session = request.getSession(true);
User user = (User)session.getAttribute("user");
session.invalidate(); // session销毁
response.sendRedirect("/OnlineUserDemo/login.html");
}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
}
User页面：
package com.tanzhou.util;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionBindingListener;
/**
*
* @author Tony Liu
*
*
*如果一个对象实现了HttpSessionBindingListener接口，当这个对象被绑定到session中或者从session中被删除时，
*Servlet容器会通知该对象。
*/
public class User implements HttpSessionBindingListener{
// 得到UserList的实例
private UserList ul = UserList.getInstance();
private String name;
public User(String name){
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
/**
* session创建对象--自动调用valueBound 用户登录
*/
@Override
public void valueBound(HttpSessionBindingEvent arg0) {
ul.addUser(name); // 添加用户
}
/**
* session销毁--自动调用valueUnbound 用户退出
*/
@Override
public void valueUnbound(HttpSessionBindingEvent arg0) {
ul.removeUser(name); //删除用户
}
}
UserList页面：
package com.tanzhou.util;
import java.util.Enumeration;
import java.util.Vector;
/**
* 用户集合类
* @author Ming
*
*
*
* 单例模式---是指一个类只有一个实例，并且能够自行的实例化
* 特点：构造方法是私有
*
* 单例模式：懒汉式单例 饿汉式单例 登记式单例
* 特点：
* 1、单例类只能有一个实例
* 2、单例类必须自己创建自己的唯一实例
* 3、单例类必须给所有其他对象提供这一实例
*/
public class UserList {
private static final UserList userList = new UserList();
/**
* List 接口一共有三个 ArrayList Vector LinkedList
*/
private Vector<String> v; //用户集合
private UserList(){
v = new Vector<String>();
}
public static UserList getInstance(){
return userList;
}
/**
* 用户登录-添加用户信息
* @param name
*/
public void addUser(String name){
if(name!=null){
v.addElement(name);
}
}
/**
* 用户退出的方法
* @param anme
*/
public void removeUser(String name){
if(name!=null){
v.remove(name);
}
}
/**
* 用户数量的统计
* @return
*/
public int getUserCount(){
return v.size();
}
/**
* Enumeration (列举)
* @return
*/
public Enumeration<String> getUserList(){
return v.elements();
}
}
