网络编程(TCP-客户端并发登录)

package netTest;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class LoginServer {

    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub
        ServerSocket ss = new ServerSocket(10003);
        // 或取多个客户端需要用到线程
        while(true){
            Socket s = ss.accept();
            new Thread(new  UserThread(s)).start();
        }
    }

}
 class UserThread implements Runnable {
    private Socket s;
    UserThread(Socket s){
        this.s = s;
    }
    @Override
    public void run() {
        // TODO Auto-generated method stub
        try{
            for(int x = 0;x<3;x++){
                BufferedReader bufIn = new BufferedReader(new InputStreamReader(s.getInputStream()));
                String name = bufIn.readLine();
                if(name == null){
                    break;
                }
                BufferedReader bufr = new BufferedReader(new FileReader("user.txt"));
                PrintWriter out = new PrintWriter(s.getOutputStream(),true);
                String line = null;
                boolean flag = false;
                while((line = bufr.readLine())!=null){
                    if(line.equals(name)){
                        flag = true;
                        break;
                    }
                }
                if(flag){
                    System.out.println(name+",已登录");
                    out.println(name+"欢迎光临");
                    break;
                }
                else{
                    System.out.println(name+",尝试登录");
                    out.println(name+"用户名不存在。");
                }
            }
            s.close();
        }
        catch(Exception e){
            e.printStackTrace();
        }
    }

}

package netTest;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;

/*
 * 只能校验三次。
 * 
 */
public class LoginClient {
    public static void main(String[] args) throws Exception, Exception {
        // TODO Auto-generated method stub
        //1.建立端点
        Socket s = new Socket(InetAddress.getLocalHost(), 10003);
        //2.组织数据(先写输入输出流 )
        BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(s.getOutputStream(),true);
        BufferedReader bufIn = new BufferedReader(new InputStreamReader(s.getInputStream()));
        //只能发送三次
        for(int x = 0;x<3;x++){
            String line = bufr.readLine();
            if(line == null){
                break;
            }
            
            out.println(line);
            String info = bufIn.readLine();
            System.out.println("info:"+info);
            if(info.contains("欢迎")){
                break;
            }
            
        }
        bufr.close();
        s.close();
    }
}