import java.net.*;
import java.io.*;
import java.util.*;


public class ChatServer {

	static int port=5656;  //端口號
  	static Vector clients=new Vector(10);   //存儲連接客戶信息
  	static ServerSocket server=null;    //建立服務(wù)器socket
  	static Socket socket=null;   //套接字連接

  	public ChatServer() {                      
		try {
  			System.err.println("Server start...");
	    	server=new ServerSocket(port);    //初始化服務(wù)器套接字
			while(true){	   
		    	socket=server.accept();   //等待連接
		    	System.err.println(socket.getInetAddress()+"連接\n"); //得到客戶機(jī)地址
		    	Client client=new Client(socket);  //實(shí)例化一個(gè)客戶線程
			    clients.addElement(client);  //增加客戶線程到向量中           		
			   	client.start();   //啟動線程
				notifyChatRoom();   //監(jiān)視聊天室連接變化					                                               
			}
		}
		catch(Exception ex) {
	    	ex.printStackTrace(); //輸出出錯(cuò)信息
		}
  	}
  	
  	public static void notifyChatRoom() {   
		StringBuffer newUser=new StringBuffer("newUser");
	 	for(int i=0;i<clients.size();i++){
	     	Client c=(Client)clients.elementAt(i);
		 	newUser.append(":"+c.name);	//客戶端姓名字符串	 
	 	}
	 	sendClients(newUser);   //發(fā)送信息到客戶端
  	}

  	public static void sendClients(StringBuffer message){ 
     	for(int i=0;i<clients.size();i++){		
	     	Client client=(Client)clients.elementAt(i); //分別得到每個(gè)客戶端的連接
		 	client.send(message);  //發(fā)送信息
	 	}
  	}

  	public void closeAll()	{   //關(guān)閉所有連接
     	while(clients.size()>0) {   //遍歷整個(gè)Vector
			Client client=(Client)clients.firstElement();  //得到一個(gè)客戶端
		 	try{
		     	client.socket.close(); //關(guān)閉端口
		 	}
		 	catch(IOException ex){
		     	ex.printStackTrace(); //輸出錯(cuò)誤信息
		 	}
		    clients.removeElement(client); //移出客戶端信息
		}
	}

 	public static void disconnect(Client c){     //斷開客戶端
		try{
		 	System.err.println(c.ip+"斷開連接\n");
	     	c.send(new StringBuffer("QUIT"));   //向客戶發(fā)送斷開連接信息
		 	c.socket=null;	//關(guān)閉端口	 
	 	}
	 	catch(Exception ex){
	    	ex.printStackTrace();
	 	}
	    clients.removeElement(c);   //移出客戶端信息
  	}
  
    public static void main(String[] args) {
    	new ChatServer();      //實(shí)例化一個(gè)ChatServer類
  	}
  	
  	class Client extends Thread  {  
	    Socket socket;    //連接端口
		String name;   //用戶姓名
		String ip;    //客戶端IP地址
	 	BufferedReader reader ;  //輸入流
		PrintStream ps;   //輸出流   
	
		public  Client(Socket s){ 	  
		   socket=s;                                           
		   try{
		       reader = new BufferedReader(new InputStreamReader(s.getInputStream())); //得到輸入流
			   ps=new PrintStream(s.getOutputStream());     //得到輸出流
			   String info=reader.readLine();   //讀取接受到的信息
			   StringTokenizer stinfo=new StringTokenizer(info,":");  //分解字符串
			   String head=stinfo.nextToken();    //獲取關(guān)鍵字
	           if(stinfo.hasMoreTokens())		   
			   		name=stinfo.nextToken();     //獲取用戶名
			   if(stinfo.hasMoreTokens())
			   		ip=stinfo.nextToken();    //獲取IP地址
		   }
		   catch(IOException ex){
		       ex.printStackTrace();
		   }
		}
		
		public void send(StringBuffer msg) {  
		   ps.println(msg);   //輸出信息
		   ps.flush();
		}
	
		public void run(){    
		   	while(true){
		       	String line=null;
			   	try{
			      line=reader.readLine();  //讀取數(shù)據(jù)流		       
			   	}
			   	catch(IOException ex){
			       ex.printStackTrace(); //輸出錯(cuò)誤信息
				   ChatServer.disconnect(this); //斷開連接
				   ChatServer.notifyChatRoom(); //更新信息
				   return;
			   	}
	
			   	if(line==null){    //客戶離開			  
				   ChatServer.disconnect(this);
				   ChatServer.notifyChatRoom();
				   return;
				}
			   
			   	StringTokenizer st=new StringTokenizer(line,":"); //分解字符串
			   	String keyword=st.nextToken();
	
			   	if(keyword.equals("MSG")){  //發(fā)送來的是聊天信息                 			  
			       	StringBuffer msg=new StringBuffer("MSG:");    
				   	msg.append(name);  //在信息上增加用戶名
				   	msg.append(st.nextToken("\0"));
				   	ChatServer.sendClients(msg);      //發(fā)送聊天語句到各個(gè)客戶端
			   	}
			   	else if(keyword.equals("QUIT")){ 	//退出命令		   		
			       	ChatServer.disconnect(this);   //斷開連接 
				   	ChatServer.notifyChatRoom();   //刷新信息 
				}
			}
		}     
	}
}