void handleMessage(Message msg);    //需要重写的方法,用来处理接收的消息,只有当接收到发送者发来的消息,才会回调该方法

Message obtainMessage();           //获取一个消息对象

boolean sendMessage(Message msg); //发送消息对象,发送成功的话,就会回调handleMessage()方法

package com.example.tcpdemo;

import java.io.IOException;

import java.net.Socket;

import java.net.UnknownHostException;

import android.os.Bundle;

import android.os.Handler;

import android.os.Message;

import android.app.Activity;

import android.view.Menu;

public class MainActivity extends Activity {

    MyThread mt;

    //定义一个handler

    public Handler mHandler = new Handler() {

        public void handleMessage(Message msg) {

            //打印发送者发来的消息

            System.out.println("main what:"+msg.what);

            System.out.println("main obj:"+msg.obj.toString());

            System.out.println("main arg1:"+msg.arg1);

        };

    };

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        mt = new MyThread();

        mt.setHandler(mHandler);    //设置handler

        mt.start();    //启动线程

    }

}

package com.example.tcpdemo;

import android.os.Handler;

import android.os.Message;

public class MyThread extends Thread {

        public Handler mHandler=null;

        //获取另一个线程的Handler

        public void setHandler( Handler handler){

            mHandler = handler;

        }

        public void run(){

             try { //让线程睡眠3s。

                    Thread.sleep(3000);

                } catch (InterruptedException e) {

                    e.printStackTrace();

                }

             Message msg = mHandler.obtainMessage();

             //设置发送的内容

             msg.arg1 = ;

             msg.what = ;

             msg.obj = "this is MyThread";

             mHandler.sendMessage(msg);

        }

}