多人聊天（无问题的）

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

public class ServerTest {

public static List clientList;

/**
 * @param args
 * @throws IOException 
 */
public static void main(String[] args) throws IOException {

    clientList=new ArrayList();
    //使服务器一直处于运行状态
    ServerSocket server=new ServerSocket(9999);

    while(true){
        Socket clientSocket = server.accept();
        //添加一个客户端
        clientList.add(clientSocket);

        //开启一个子线程
        MyThread myThread=new ServerTest().new MyThread(clientSocket);
        myThread.start();
    }


}

class MyThread extends Thread{
    private Socket sc;


    public MyThread(){}
    public MyThread(Socket s){
        sc=s;
    }
    @Override
    public void run() {

        try {
            InputStream inputStream = sc.getInputStream();

BufferedReader br=new BufferedReader(new InputStreamReader(inputStream,”utf-8”));

            String con;
            while((con=br.readLine())!=null){
                System.out.println("来自客户端的消息："+con);

                //将接收到的消息发送给每一个连接到的客户端
                for(Socket s:clientList){
                    OutputStream outputStream = s.getOutputStream();
                    outputStream.write((con+"\r\n").getBytes("utf-8"));

// outputStream.flush();
}

            }

            br.close();
            inputStream.close();



        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}

}
————————————————–package com.example.androidclient;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.Socket;
import java.net.UnknownHostException;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity {

private EditText etContent;
private Socket client;
private OutputStream os;
private TextView tvMsg;



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    etContent = (EditText) findViewById(R.id.etContent);
    tvMsg = (TextView) findViewById(R.id.tvMsg);
    new Thread(){

        String content;


        public void run() {

            try {
                Socket s = new Socket("20.1.5.125",9999);
                s.setKeepAlive(true);
                if(s.isConnected()){
                    System.out.println("服务器连接成功..");
                }
                os = s.getOutputStream();

                InputStream is = s.getInputStream();
                BufferedReader br = new BufferedReader(
                        new InputStreamReader(is));
                //System.out.println("开始读取服务器的内容  ： "+br.readLine());
                while((content = br.readLine()) != null){
                    System.out.println("来自服务器 ： "+content);

                    runOnUiThread(new Runnable() {

                        @Override
                        public void run() {

                            System.out.println("来自服务器 ： "+content);
                            tvMsg.append("张三 : "+content);

                        }
                    });
                }

            } catch (Exception e) {
                e.printStackTrace();
            }

        };
    }.start();



}



public void btnSendMsg(View v){


    String chat = etContent.getText().toString();
    if(os != null){
        try {
            os.write((chat+"\r\n").getBytes());
            os.flush();
        } catch (Exception e) {
            e.printStackTrace();
        }   
    }

}