Android在service中实现随机数产生

1、在service中实现随机数产生；
2、实现Service中的各个生命周期函数，并理解其功能；
2、在Activity界面实现随机数的显示，每2秒更新一次；
3、采用启动式完成service的启动；

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

    <TextView
        android:id="@+id/txt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="TextView" />
    <Button
        android:id="@+id/start"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="startService"
        android:text="startService"
        />

    <Button
        android:id="@+id/stop"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="stopService"
        android:text="stopService"
        />



</LinearLayout>

MainActivity

package com.example.myapplication22;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.content.Intent;
import android.os.IBinder;
import android.view.View;
import android.widget.TextView;


public class MainActivity extends Activity {

    private TextView txt;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        txt = findViewById(R.id.txt);
    }

    private Handler mHandler = new Handler();
    Runnable runnable = new Runnable() {
        @Override
        public void run() {
            txt.setText(String.valueOf(Math.random()*100));
            mHandler.postDelayed(this, 2000);
        }
    };
    Thread thread = new Thread(runnable);

    public void startService(View view) {
        startService(new Intent(getBaseContext(), MyServiceToStart.class));
        thread.start();
    }

    public void stopService(View view) {
        mHandler.removeCallbacks(runnable);
        stopService(new Intent(getBaseContext(), MyServiceToStart.class));
    }







}

MyServiceToStart

package com.example.myapplication22;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;

import android.widget.Toast;

public class MyServiceToStart extends Service {

    @Override
    public IBinder onBind(Intent arg0) {
        return null;
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Toast.makeText(this, "服务已经启动", Toast.LENGTH_LONG).show();
        return START_STICKY;
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Toast.makeText(this, "服务已经停止", Toast.LENGTH_LONG).show();
    }



}