package com.example.double2.sockettesttwo;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

 private EditText etMain;
 private Button btnMain;
 private TextView tvMain;
 private ClientThread mClientThread;

 //在主线程中定义Handler传入子线程用于更新TextView
 private Handler mHandler;

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

 etMain = (EditText) findViewById(R.id.et_main);
 btnMain = (Button) findViewById(R.id.btn_main);
 tvMain = (TextView) findViewById(R.id.tv_main);

 mHandler=new Handler() {
  @Override
  public void handleMessage(Message msg) {
  if (msg.what == 0) {
   tvMain.append("\n" + msg.obj.toString());
  }
  }
 };

 //点击button时，获取EditText中string并且调用子线程的Handler发送到服务器
 btnMain.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
  try {
   Message msg = new Message();
   msg.what = 1;
   msg.obj = etMain.getText().toString();
   mClientThread.revHandler.sendMessage(msg);
   etMain.setText("");
  } catch (Exception e) {
   e.printStackTrace();
  }
  }
 });


 mClientThread = new ClientThread(mHandler);
 new Thread(mClientThread).start();


 }
}

package com.example.double2.sockettesttwo;

import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.util.Log;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.Socket;

/**
 * 项目名称：SocketTestTwo
 * 创建人：Double2号
 * 创建时间：2016.11.20 9:16
 * 修改备注：
 */
public class ClientThread implements Runnable {
 private Socket mSocket;
 private BufferedReader mBufferedReader = null;
 private OutputStream mOutputStream = null;
 private Handler mHandler;

 public Handler revHandler;

 public ClientThread(Handler handler) {
 mHandler = handler;
 }

 @Override
 public void run() {
 try {
  mSocket = new Socket("10.3.20.159", 30003);
  Log.d("xjj","connect success");
  mBufferedReader = new BufferedReader(new InputStreamReader(mSocket.getInputStream()));
  mOutputStream = mSocket.getOutputStream();

  new Thread(){
  @Override
  public void run() {
   super.run();
   try {
   String content = null;
   while ((content = mBufferedReader.readLine()) != null) {
    Log.d("xjj",content);
    Message msg = new Message();
    msg.what = 0;
    msg.obj = content;
    mHandler.sendMessage(msg);
   }
   }catch (IOException e){
   e.printStackTrace();
   }
  }
  }.start();

  //由于子线程中没有默认初始化Looper，要在子线程中创建Handler，需要自己写
  Looper.prepare();
  revHandler = new Handler() {
  @Override
  public void handleMessage(Message msg) {
   if (msg.what == 1) {
   try {
    mOutputStream.write((msg.obj.toString() + "\r\n").getBytes("utf-8"));
   } catch (IOException e) {
    e.printStackTrace();
   }
   }
  }
  };
  Looper.loop();



 } catch (IOException e) {
  e.printStackTrace();
  Log.d("xjj","");
 }
 }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
 android:id="@+id/activity_main"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:padding="@dimen/activity_vertical_margin"
 android:orientation="vertical"
 >

 <LinearLayout
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:orientation="horizontal">

 <EditText
  android:id="@+id/et_main"
  android:layout_width="0dp"
  android:layout_height="wrap_content"
  android:layout_weight="1"/>

 <Button
  android:id="@+id/btn_main"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="@string/send"/>
 </LinearLayout>

 <TextView
 android:id="@+id/tv_main"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 />
</LinearLayout>

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;

public class MySever {

 public static ArrayList<Socket> socketList = new ArrayList<Socket>();
 public static String content="";

 public static void main(String[] args) throws IOException {
 //建立ServerSocket
 ServerSocket ss = new ServerSocket(30003);

 //不断接收此端口的socket，并存储到socketList中
 //并且为每一个socket开启一个线程，用于接收信息
 while (true) {
  Socket s = ss.accept();
  System.out.println("connect success!");
  socketList.add(s);

  new Thread(new ServerThread(s)).start();
 }
 }

}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.Socket;
import java.net.SocketException;
import java.util.Iterator;

public class ServerThread implements Runnable {

 private Socket mSocket = null;
 private BufferedReader mBufferedReader = null;

 // 构造函数中接收socket并且初始化BufferedReader
 public ServerThread(Socket socket) 
  throws UnsupportedEncodingException, IOException {
 mSocket = socket;
 mBufferedReader = new BufferedReader(
  new InputStreamReader(mSocket.getInputStream(), "utf-8"));
 }

 @Override
 public void run() {
 // TODO Auto-generated method stub

 try {
  String content = null;

  //循环接收来自此客户端的消息
  //如果接收不到了，表面已经断开，就将此客户端从socketList中移除
  while ((content = mBufferedReader.readLine()) != null) {

  System.out.println(content);

  //向连接中的每个客户端发送数据
  //如果异常，说明断开，就将该条目从socketList中移除
  for (Iterator<Socket> it = MySever.socketList.iterator(); 
   it.hasNext();) {
   Socket s = it.next();
   try {
   OutputStream os = s.getOutputStream();
   os.write((content + "\n").getBytes("utf-8"));
   } catch (SocketException e) {
   e.printStackTrace();
   it.remove();
   }
  }
  }
 } catch (IOException e) {
  e.printStackTrace();
  MySever.socketList.remove(mSocket);
 }
 }

}