如何在Android中创建未绑定的服务？

Question

Android上的服务的很多示例和教程都适用于bound services，但如果我想创建未绑定的服务而不必处理绑定呢？

 

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Answer 1

做的第一件事是将服务添加到您的清单中，<application>标签中：

<application ...> 

    ...   

    <service 
     android:name=".RecordingService" 
     android:exported="false"> 

</application> 

然后我们创建实际的服务类：

public class RecordingService extends Service { 
    private int NOTIFICATION = 1; // Unique identifier for our notification 

    public static boolean isRunning = false; 
    public static RecordingService instance = null; 


    private NotificationManager notificationManager = null; 


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

    @Override 
    public void onCreate(){ 
     instance = this; 
     isRunning = true; 

     notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE); 

     super.onCreate(); 
    } 

    @Override 
    public int onStartCommand(Intent intent, int flags, int startId){ 
     // The PendingIntent to launch our activity if the user selects this notification 
     PendingIntent contentIntent = PendingIntent.getActivity(this, 0, new Intent(this, MainActivity.class), 0); 

     // Set the info for the views that show in the notification panel. 
     Notification notification = new NotificationCompat.Builder(this) 
       .setSmallIcon(R.mipmap.ic_launcher)  // the status icon 
       .setTicker("Service running...")   // the status text 
       .setWhen(System.currentTimeMillis())  // the time stamp 
       .setContentTitle("My App")     // the label of the entry 
       .setContentText("Service running...")  // the content of the entry 
       .setContentIntent(contentIntent)   // the intent to send when the entry is clicked 
       .setOngoing(true)       // make persistent (disable swipe-away) 
       .build(); 

     // Start service in foreground mode 
     startForeground(NOTIFICATION, notification); 

     return START_STICKY; 
    } 


    @Override 
    public void onDestroy(){ 
     isRunning = false; 
     instance = null; 

     notificationManager.cancel(NOTIFICATION); // Remove notification 

     super.onDestroy(); 
    } 


    public void doSomething(){ 
     Toast.makeText(getApplicationContext(), "Doing stuff from service...", Toast.LENGTH_SHORT).show(); 
    } 

} 

所有这些服务确实是在运行时显示通知，并且在调用doSomething()方法时可以显示吐司。

正如你会注意到的，它被实现为singleton，跟踪它自己的实例 - 但没有通常的静态singleton工厂方法，因为服务自然是单例并且是由意图创建的。这个实例在运行时对于服务获得“处理”是有用的。

最后，我们需要启动和从活动停止服务：

public void startOrStopService(){ 
    if(RecordingService.isRunning){ 
     // Stop service 
     Intent intent = new Intent(this, RecordingService.class); 
     stopService(intent); 
    } 
    else { 
     // Start service 
     Intent intent = new Intent(this, RecordingService.class); 
     startService(intent); 
    } 
} 

在这个例子中，该服务已启动，并用同样的方法停止，这取决于它的当前状态。

我们也可以从我们的活动调用doSomething()方法：

public void makeServiceDoSomething(){ 
    if(RecordingService.isRunning) 
     RecordingService.instance.doSomething(); 
}