controller.java

JAVA聊天室servlet实现 纯servlet实现的聊天系统 注释清楚 易于理解

package com.controller;

import java.io.IOException;
import java.util.ArrayList;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
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.bean.UserInfoBean;
import com.bean.UserInfoDao;

/**
 * 验证用户名在数据库中是否存在
 * @author Administrator
 *
 */

public class Controller extends HttpServlet {
	
	public  ArrayList<UserInfoBean> al =new ArrayList<UserInfoBean> ();
	
	public void doGet(HttpServletRequest request,HttpServletResponse response)
	throws ServletException,IOException {
		
		response.setContentType("text/html;charset=GBK");
		
	
		
		/**
		 * 取得用户名和密码
		 */
		String UserName =request.getParameter("UserName");
		String pwd =request.getParameter("pwd");
		
		
		
		//封装成对象
			UserInfoBean uib = new UserInfoBean();
			uib.setPwd(pwd);
			uib.setUserName(UserName);
		
		//验证是否在数据库中存在
			UserInfoDao  uid = new UserInfoDao();
			boolean  b =uid.YanZhen(uib);		
			String url ="UserPeopleView";
//			
			
			/**
			 * 根据不同的情况显示不同的提示信息
			 * 如果为空  返回登录界面  返回用户名和密码错误
			 * 
			 * 如果是用户已登录  则提示用户已 登录
			 */
			if (!b) {
				url ="denluView";
				HttpSession  session =request.getSession();
				String str="你输入的用户名和密码或密码错误";
				session.setAttribute("alter", str);				
			
				
			}else {
				/**
				 * 保存登录的用户并转到显示页ChatpaneView
				 */
				
				/**
				 * 如果用户已登录  则提示
				 */
				boolean flag =false;
				
				ServletContext application1 =this.getServletContext();//获取application
				ArrayList<UserInfoBean> a2= (ArrayList)application1.getAttribute("al");
				if (a2!=null) {
				for (int i=0;i<a2.size();i++) {					
					if (a2.get(i).getUserName().equals(uib.getUserName())) {
						System.out.println(a2.get(i).getUserName());
						System.out.println(uib.getUserName());
						flag =true;
						url ="denluView";
						HttpSession  session2 =request.getSession();
						String havedLogin="你已登录,请另外选择一个用户登录";
						session2.setAttribute("havedLogin",havedLogin );	
						break;
				  }
				}
				}					
				if (!flag){
						url="ChatPaneView";							
						al.add(uib);
						
//						将用户列表存入application 
						ServletContext application =this.getServletContext();
					    application.setAttribute("al", al);
					    
//					  将当前用户存起来
						HttpSession session  =request.getSession();
						session.setAttribute("uib", uib);					    
					}			
			}
			
			
			//跳转页面
           //转发去显示结果的servlet
			RequestDispatcher dispatcher = request.getRequestDispatcher(url);//从指定的url得到一个请求传发器对象
			dispatcher.forward(request, response);//请求转发
			
			
			
	}

}