Android Service开发应用实例

Service 开发应用在后台长时间运行，没有界面UI，在后台下载文件和获取用户GPS信息 Service：分为 startService 和 Bound

Service 开发应用

在后台长时间运行，没有界面UI，在后台下载文件和获取用户GPS信息

Service：分为 startService 和 BoundService；
只有Activity 调用startService才会通知服务启动， BoundService只Activity bindService 进行启动。
Service中Export 和Enable两个属性， Export 应用组件能不能调用被Service， Enable：表示Service能不能被实例化。
重写onBind ,onCreate,onStartCommand,onDestory 这个四个方法。
在调用Service 时候判断本Service是否在正在运行

// 需要在XML文件中配准Service Bound
   <service
            android:name=".MusicService"
            android:enabled="true"
            android:exported="true"></service>
  public boolean isRunning() {
        ActivityManager activityManager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
        ArrayList<ActivityManager.RunningServiceInfo> runningServiceInfoArrayList
                = (ArrayList< ActivityManager.RunningServiceInfo>) activityManager.getRunningServices(10);
        for(int i=0;i <runningServiceInfoArrayList.size();i++){
            if(runningServiceInfoArrayList.get(i).service.getClassName().toString().equals("com.example.myapplication.MyService")) {
                return true;
            }
        }
        return false;
    }

package com.example.myapplication;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.WindowManager;
import android.widget.ImageButton;
public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //设置全屏显示
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);
        ImageButton btn_play = (ImageButton) findViewById(R.id.btn_play);//获取“播放/停止”按钮
        //启动服务与停止服务，实现播放背景音乐与停止播放背景音乐
        btn_play.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (MusicService.isPlay == false) {   //判断音乐播放的状态
                    startService(new Intent(MainActivity.this, MusicService.class));  //启动服务，从而实现播放背景音乐
                    //更换播放背景音乐图标
                    ((ImageButton) v).setImageDrawable(getResources().getDrawable(R.drawable.play, null));
                } else {
                    stopService(new Intent(MainActivity.this, MusicService.class));  //停止服务，从而实现停止播放背景音乐
                    //更换停止背景音乐图标
                    ((ImageButton) v).setImageDrawable(getResources().getDrawable(R.drawable.stop, null));
                }
            }
        });
    }
    @Override
    protected void onStart() {  //实现进入界面时，启动背景音乐服务
       startService(new Intent(MainActivity.this, MusicService.class));  //启动服务，从而实现播放背景音乐
        super.onStart();
    }
}

package com.example.myapplication;
import android.app.Service;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.IBinder;
public class MusicService extends Service {
    public MusicService() {
    }
    static boolean isPlay =false;
    private MediaPlayer player;
    @Override
    public IBinder onBind(Intent intent) {
        // TODO: Return the communication channel to the service.
        throw new UnsupportedOperationException("Not yet implemented");
    }
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        // 判断播放状态
        if(player.isPlaying()) {
            player.start();
            isPlay = player.isPlaying();
        }
        return super.onStartCommand(intent, flags, startId);
    }
    @Override
    public void onCreate() {
        // 创建MediaPlay对象，加载播放音频对象
        player = MediaPlayer.create(this,R.raw.music);
        super.onCreate();
    }
    @Override
    public void onDestroy() {
        player.stop();
        isPlay = player.isPlaying();
        player.release();
        super.onDestroy();
    }
}

注意在Android 8.0 后不允许在后台创建Service 上面有问题需要调整

BindService

Service对象中创建一个MyBinder类型的绑定器，返回其绑定对象
Activity中 ServiceConnection 重写其中方法，在此方法中获取Service独享

package com.example.myapplication;
import androidx.appcompat.app.AppCompatActivity;
import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import java.util.List;
public class MainActivity extends AppCompatActivity {
    BinderService binderService;   //声明BinderService
    //文本框组件ID
    int[] tvid = {R.id.textView1, R.id.textView2, R.id.textView3, R.id.textView4, R.id.textView5,
            R.id.textView6, R.id.textView7};
    // 创建ServiceConnection 对象
    private ServiceConnection serviceConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            binderService =  ((BinderService.MyBinder) iBinder).getService();
        }
        @Override
        public void onServiceDisconnected(ComponentName componentName) {
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button btn_random = (Button) findViewById(R.id.btn);  //获取随机选号按钮
        btn_random.setOnClickListener(new View.OnClickListener() {  //单击按钮，获取随机彩票号码
            @Override
            public void onClick(View v) {
                List number = binderService.getRandomNumber();  //获取BinderService类中的随机数数组
                for (int i = 0; i < number.size(); i++) {  //遍历数组并显示
                    TextView tv = (TextView) findViewById(tvid[i]);  //获取文本框组件对象
                    String strNumber = number.get(i).toString();     //将获取的号码转为String类型
                    tv.setText(strNumber);  //显示生成的随机号码
                }
            }
        });
    }
    @Override
    protected void onStart() {  //设置启动Activity时与后台Service进行绑定
        super.onStart();
        Intent intent = new Intent(this, BinderService.class);  //创建启动Service的Intent
        bindService(intent, serviceConnection, BIND_AUTO_CREATE);           //绑定指定Service
    }
    @Override
    protected void onStop() {  //设置关闭Activity时解除与后台Service的绑定
        super.onStop();
        unbindService(serviceConnection);    //解除绑定Service
    }
}

package com.example.myapplication;
import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
public class BinderService extends Service {
    public BinderService() {
    }
    // 创建MyBinder 内部类
    public class MyBinder extends Binder {
        public BinderService getService() {
            return BinderService.this;
        }
    }
    @Override
    public IBinder onBind(Intent intent) {
        // TODO: Return the communication channel to the service.
        return new MyBinder();
    }
    public List getRandomNumber() {  //创建获取随机号码的方法
        List resArr = new ArrayList();   //创建ArrayList数组
        String strNumber="";
        for (int i = 0; i < 7; i++) {  //将随机获取的数字转换为字符串添加到ArrayList数组中
            int number = new Random().nextInt(33) + 1;
            //把生成的随机数格式化为两位的字符串
            if (number<10) {  //在数字1~9前加0
                strNumber = "0" + String.valueOf(number);
            } else {
                strNumber=String.valueOf(number);
            }
            resArr.add(strNumber);
        }
        return resArr;  //将数组返回
    }
    @Override
    public void onDestroy() {  //销毁该Service
        super.onDestroy();
    }
}