功能描述：

        点击'启动service’按钮后启动后台线程，点击“停止service”按钮后关闭线程。后台线程每一秒产生一个随机数，并通过Handler将产生的随机数显示在用户界面上。

activity_main.xml文件

 

MainActivity.java文件

package com.example.pprp.myapplication2_lh;import android.app.Activity;import android.app.Service;import android.content.Intent;import android.os.Handler;import android.os.IBinder;import android.support.annotation.Nullable;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.TextView;public class MainActivity extends Activity {    private static TextView tv01=null;    Button btnstart;    Button btnstop;    private static Handler handler=new Handler();    private static double randomnum;    public static void UpdateGUI(double refreshDouble){        randomnum=refreshDouble;        handler.post(RefreshLable);    }    private static Runnable RefreshLable=new Runnable() {        @Override        public void run() {            tv01.setText(String.valueOf(randomnum));        }    };    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        tv01=(TextView)findViewById(R.id.tv01);        btnstart=(Button)findViewById(R.id.btnstart);        btnstop=(Button)findViewById(R.id.btnstop);        final Intent serviceintent=new Intent(this,ThreadActivity.class); //连接两个java文件的媒介        btnstart.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                startService(serviceintent); //开始线程            }        });        btnstop.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                stopService(serviceintent); //停止线程            }        });    }}

 

ThreadActivity .java文件

package com.example.pprp.myapplication2_lh;import android.app.Activity;import android.app.Service;import android.content.Intent;import android.os.Handler;import android.os.IBinder;import android.support.annotation.Nullable;import android.widget.TextView; /** * Created by lh on 2018/11/21. */public class ThreadActivity extends Service{    private Thread thread;    @Override    public void onCreate() {        super.onCreate();        thread=new Thread(null,backgroundwork,"thread"); //创建线程,将Runnable对象作为参数传递给thread,第三个参数是线程的名称     }    @Override    public void onStart(Intent intent, int startId) {        super.onStart(intent, startId);        if(!thread.isAlive()){            thread.start();        }    }    @Override    public void onDestroy() {        super.onDestroy();        thread.interrupt();    }    @Nullable    @Override    public IBinder onBind(Intent intent) {        return null;    }    private Runnable backgroundwork=new Runnable() { //在run（）中放置代码的主体部分        @Override        public void run() {            try {                while(!thread.interrupted()){                    double randomnum=Math.random();                    MainActivity.UpdateGUI(randomnum);                    Thread.sleep(1000);                }            }catch (InterruptedException e){                e.printStackTrace();            }        }    };}

 

AndroidManifest.xml文件：新建立的threadactivity.java文件是service类型，所以在AndroidManifest.xml中注册时需注意写成service.