1: 首先第一点Service 不是子线程,这个一定要明确的,这个service是在后台运行,这里所谓的后台其实指的是没有界面而已
2: Service 分文Service 和IntentService(自带子线程)
3: Service的启动方式包含startService(和startActivity很类似) 和bindService,
通过startService启动的Service被删除的方法有哪两种?stopSelf() stopService
4: Service 和Messager的关系
5: onBind 方法:如果其他应用程序组件和服务进行绑定的时候,会自动回调这个方法, 返回null 或者是抛出异常不允许绑定服务
onCreate方法:当服务第一次启动之前,有系统来创建服务,并且调用这个方法,不管启动多少次,都只运行一次
onStartCommand方法:在每次执行startService的时候,都会调用,那么bindService的时候呢?应该是不调用的
onStartCommand方法是由主线程调用的,千万不要执行耗时的操作,可以在子线程中执行耗时操作
打印出当前的Thread.currentThread().toString(). 就会发现,的确是主线程调用的,所以千万不要执行耗时操作。
kodulf.servicedemo D/kodulf: onStartCommand: GOODThread[main,5,main]
kodulf.servicedemo D/kodulf: startServiceOne: Thread[main,5,main]
返回值,代表服务能否复活:
IntentService的onHandleIntent(Intent intent)
IntentService 通过打印log,我们可以发现的确是运行在一个新的子线程中的
2019-03-11 08:25:43.854 31734-31734/kodulf.servicedemo D/kodulf: startIntentService Thread[main,5,main]
2019-03-11 08:25:43.929 31734-31817/kodulf.servicedemo D/kodulf: onHandleIntent: www.baidu.comThread[IntentService[test],5,main]
onDestory 方法: 一定要在这个方法里面进行资源的释放,例如播放音乐的话,就需要释放掉音乐的资源
onDestory 的方法会在3个情况下调用:应用被强制关闭,stopSelf(), stopService,应该还有其他的情况
++++++++++++++++++++++++++++++++++++++
删除了进程什么意思?就是调用stopSelf()和stopService()来删除啊!
如果删除了进程后,会报错。 这个时候优化: 添加if(intent!=null){ return START_REDELIVER_INTENT if(intent!=null){ String action = intent.getStringExtra("action"); if(action!=null){ if(action.equals("play")){ //代表播放 player.start(); }else if(action.equals("pause")){ //代表暂停 player.pause(); } } } return START_REDELIVER_INTENT;
package kodulf.servicedemo.services;
import android.app.Service;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.IBinder;
import android.util.Log;
import kodulf.servicedemo.R;
public class ServiceStandar extends Service {
private String TAG = "kodulf";
private MediaPlayer mMediaPlayer;
public ServiceStandar() {
}
/**
* 如果其他的应用程序组件和服务进行绑定过的时候,会自动调用这个方法
* @param intent
* @return
*/
@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
throw new UnsupportedOperationException("Not yet implemented");
}
@Override
public void onCreate() {
super.onCreate();
mMediaPlayer = MediaPlayer.create(this,R.raw.threed);
mMediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
@Override
public void onCompletion(MediaPlayer mp) {
Log.d(TAG, "onCompletion: music");
}
});
Log.d(TAG, "onCreate: ");
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "onStartCommand: ");
String test = intent.getStringExtra("Action");
Log.d(TAG, "onStartCommand: " + test +Thread.currentThread().toString());
// return super.onStartCommand(intent, flags, startId);
if("start".equals(test)){
mMediaPlayer.start();
}else if("stop".equals(test)){
mMediaPlayer.pause();
}else if("stopService".equals(test)){
stopSelf();
}
//失忆后找回记忆
return Service.START_STICKY;
}
@Override
public void onDestroy() {
super.onDestroy();
Log.d(TAG, "onDestroy: ");
if(mMediaPlayer!=null) {
mMediaPlayer.pause();
mMediaPlayer.stop();//停止播放
mMediaPlayer.release();//释放资源
}
}
}
package kodulf.servicedemo;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import kodulf.servicedemo.services.ServiceStandar;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void startServiceOne(View view) {
Intent intent = new Intent(this,ServiceStandar.class);
intent.putExtra("Action","start");
Log.d("kodulf", "startServiceOne: " +Thread.currentThread().toString());
startService(intent);
}
public void stopMusic(View view) {
Intent intent = new Intent(this,ServiceStandar.class);
intent.putExtra("Action","stop");
Log.d("kodulf", "stopMusic: " +Thread.currentThread().toString());
startService(intent);
}
public void stopService(View view) {
Intent intent = new Intent(this,ServiceStandar.class);
stopService(intent);
}
public void stopServiceUsingStopSelf(View view) {
Intent intent = new Intent(this,ServiceStandar.class);
intent.putExtra("Action","stopService");
Log.d("kodulf", "stopService " +Thread.currentThread().toString());
stopService(intent);
}
}
Messager: