如何用javaweb来写在线聊天应用

写这个玩意儿就是想练练手，用户需要登陆才能在线聊天，不要依赖数据库，不需要数据库的操作，所有的数据都是保存在内存中，如果服务器一旦重启，数据就没有了；

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登录界面：

聊天界面：

左侧是在线的用户列表，右侧是聊天的内容，内容的格式为 “作者：内容”；

点击button可以发布聊天信息；

使用的是spring搭建的框架，基于tomcat的服务器；

web.xml的配置如下：

 
 
  
     
    
  
    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_3_0.xsd">   
           
       
      index.htm   
       
       
       
      test   
      org.springframework.web.servlet.DispatcherServlet   
      1   
         
     
         
      test   
      *.htm   
         
     
         
          org.springframework.web.context.ContextLoaderListener   
         
         
         
          CharacterEncodingFilter   
          com.nono.Filter.CharacterEncodingFilter   
             
              encoding   
              UTF-8   
             
         
         
           
          SecurityServlet     
          com.nono.SecurityServlet     
           
           
          SecurityServlet     
          *.htm     
         
         
     
         
        
         
             
          contextConfigLocation   
             
             
          /WEB-INF/test-servlet.xml

conteConfigLocation的配置为：

 
 
  
     
    
  
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"   
   xmlns:context="http://www.springframework.org/schema/context"   
   xmlns:aop="http://www.springframework.org/schema/aop"   
   xmlns:tx="http://www.springframework.org/schema/tx"   
   xmlns:mvc="http://www.springframework.org/schema/mvc"   
   xmlns:task="http://www.springframework.org/schema/task"   
   xsi:schemaLocation="http://www.springframework.org/schema/beans   
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd   
        http://www.springframework.org/schema/context   
        http://www.springframework.org/schema/context/spring-context-3.0.xsd   
        http://www.springframework.org/schema/tx   
        http://www.springframework.org/schema/tx/spring-tx-3.0.xsd   
        http://www.springframework.org/schema/aop   
        http://www.springframework.org/schema/aop/spring-aop-3.0.xsd   
        http://www.springframework.org/schema/mvc   
        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd   
        http://www.springframework.org/schema/task   
        http://www.springframework.org/schema/task/spring-task-3.0.xsd">   
         
     
          
          
         
         
             
              .jsp

整个项目的结构为一个主路由，四个po层, 两个过滤器：

界面的用户列表和用户内容列表用了ajax刷新，感觉不错的说：

 
 
  
     
  <%@ page language="java" import="java.util.*"  pageEncoding="utf-8"%>   
  <%   
  String path = request.getContextPath();   
  String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";   
  %>   
     
     
     
       
      ">   
         
      login   
         
         
         
       
       
       
             
                 
                     
                         
                             
                              list   
                             
                             
                              
name   
                              
name   
                              
name   
                              
name

package com.nono;
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;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.nono.po.User;
public class SecurityServlet extends HttpServlet implements Filter {
private static final long serialVersionUID = 1L;
public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2) throws IOException, ServletException {
HttpServletRequest request=(HttpServletRequest)arg0;
HttpServletResponse response =(HttpServletResponse) arg1;
HttpSession session = request.getSession();
User user = (User) session.getAttribute("user");
String url=request.getRequestURI();
//如果用户信息不是空的，或者要访问的是登陆的界面(get,post的方式包含了login字符串);
if( user!=null || url.indexOf("login")>-1 ) {
arg2.doFilter(arg0, arg1);
return;
}else{
//余下的全跳到登陆界面
response.sendRedirect(request.getContextPath() + "/login.htm");
return;
}
}
public void init(FilterConfig arg0) throws ServletException {
}
}

package com.nono.Controller;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Vector;
import javax.jms.Session;
import javax.print.DocFlavor.STRING;
import javax.print.attribute.HashAttributeSet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import net.sf.json.JSONArray;
import org.omg.CORBA.PUBLIC_MEMBER;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import com.nono.po.Content;
import com.nono.po.Contents;
import com.nono.po.User;
import com.nono.po.Users;
@Controller
public class MainController {
//用户和用户组;
@Autowired
Users users;
@Autowired
Contents contents;
@RequestMapping(value="login", method=RequestMethod.GET)
public String login (HttpServletRequest request) {
return "login";
}
@RequestMapping(value="login", method=RequestMethod.POST)
public String loginPOST ( HttpServletRequest request, HttpServletResponse response ) {
String string = "login";
String name = (String) request.getParameter("name");
Boolean flag = true;
//如果名字不是空的话;
if( !name.equals("") ) {
Vector vector = users.getList();
for(int i=0; i< vector.size(); i++) {
User user = (User) vector.elementAt(i);
if( user.getName().equals( name ) ) {
flag = false;
};
};
};
//用户名不存在
if( flag ) {
User user = new User();
user.setName( name );
HttpSession session = request.getSession(true);
//设置Session的过期时间为10分钟
session.setMaxInactiveInterval(600);
//设置seesion中的用户信息;
session.setAttribute("user", user);
//添加用户;
users.addUser( user );
//加入的提示;
Content content = new Content();
content.setName( name );
content.setContent( "enter the chat room!" );
contents.addContent( content );
string = "chat";
return string;
}else{
//用户名已经存在
request.setAttribute("info", "用户名已经存在1");
string = "login";
return string;
}
}
@RequestMapping(value="chat", method=RequestMethod.GET)
public String main (HttpServletRequest request) {
String string = "chat";
return string;
}
@RequestMapping(value="chat", method=RequestMethod.POST)
@ResponseBody
public String chat(HttpServletRequest request) {
String string = (String) request.getParameter("content");
HttpSession session = request.getSession();
//设置seesion中的用户信息;
User user = (User) session.getAttribute("user");
String name = user.getName();
Content content = new Content();
content.setName( name );
content.setContent( string );
contents.addContent( content );
return "true";
}
@RequestMapping(value="getList", method=RequestMethod.POST, produces = "text/html;charset=UTF-8")
@ResponseBody
public String getList( HttpServletRequest request) {
return JSONArray.fromObject( users.getList() ).toString();
}
@RequestMapping(value="getContent", method=RequestMethod.POST, produces = "text/html;charset=UTF-8")
@ResponseBody
public String getArrayList() {
ArrayList list = (ArrayList) contents.getContents();
ArrayList result = new ArrayList();
for( int i= 0; i< list.size(); i++ ) {
HashMap hashMap = new HashMap();
hashMap.put("name", ((Content)list.get(i)).getName());
hashMap.put("content", ((Content)list.get(i)).getContent());
result.add( hashMap );
};
return JSONArray.fromObject( result ).toString();
}
}