Android：将服务中的传感器数据广播到活动

Question

我正在尝试学习Android应用程序开发，并编写了一个非常简单的应用程序，由一个调用服务的活动组成。该服务向活动广播测量的加速度。问题是服务运行正常，但不会将数据发送回活动。即onReceive在我的接收器上永远不会被调用。另外，当活动结束时，有一个例外说明我的接收器尚未注册。以下是我的服务，活动和manifest.xml的代码。任何帮助将非常感激。

活动呼叫服务：

package com.practice; 
import com.practice.SimpleService; 
import android.app.Activity; 
import android.content.BroadcastReceiver; 
import android.content.Context; 
import android.content.Intent; 
import android.content.IntentFilter; 
import android.os.Bundle; 
import android.util.Log; 
import android.view.Window; 

public class ServiceActivity extends Activity { 
MyReceiver myReceiver=null; 
Intent i; 
static final String LOG_TAG = "ServiceActivity"; 

/** Called when the activity is first created. */ 
@Override 
public void onCreate(Bundle savedInstanceState) { 
    Log.d(LOG_TAG, "onCreate"); 
    super.onCreate(savedInstanceState); 
    requestWindowFeature(Window.FEATURE_NO_TITLE); 
    setContentView(R.layout.main); 

    //Start service 
    i= new Intent(this, com.practice.SimpleService.class); 
    Log.d(LOG_TAG, "onCreate/startService"); 
} 
@Override 
public void onResume(){ 
    super.onResume(); 
    Log.d(LOG_TAG, "onResume/registering receiver"); 
    //Register BroadcastReceiver to receive accelerometer data from service 
    //if (myReceiver == null){ 
     myReceiver = new MyReceiver(); 
     IntentFilter intentFilter = new IntentFilter();  
     intentFilter.addAction(SimpleService.MY_ACTION); 
     startService(i); 
     registerReceiver(myReceiver, intentFilter); 
    //}  
} 

@Override 
public void onPause(){ 
    super.onPause(); 
    Log.d(LOG_TAG, "onPause/unregistering receiver"); 
    stopService(i); 

    if (myReceiver != null)unregisterReceiver(myReceiver);  
} 

@Override 
protected void onStop(){ 
    super.onStop(); 
    Log.d(LOG_TAG, "onStop"); 
    if (myReceiver != null) unregisterReceiver (myReceiver); 
    stopService(i); 
} 

private class MyReceiver extends BroadcastReceiver{ 
    static final String Log_Tag = "MyReceiver"; 
    @Override 
    public void onReceive(Context arg0, Intent arg1){ 
     Log.d(LOG_TAG, "onReceive"); 
     String measurement = arg1.getStringExtra("measurement");   
     System.out.println("I am here"); 
    } 

} 

}

服务获取的传感器数据：

package com.practice; 
import java.util.List; 
import android.app.Service; 
import android.content.Intent; 
import android.hardware.Sensor; 
import android.hardware.SensorEvent; 
import android.hardware.SensorEventListener; 
import android.hardware.SensorManager; 
import android.os.IBinder; 
import android.util.Log; 
import android.widget.TextView; 

public class SimpleService extends Service implements SensorEventListener{ 
final static String MY_ACTION = "MY_ACTION"; 
    private TextView output; 
    private String reading; 
    private SensorManager mgr; 
    private List<Sensor> sensorList; 
    static final String LOG_TAG = "SimpleService"; 
    Intent intent = new Intent("com.practice.SimpleService.MY_ACTION"); 

    @Override 
    //public void onStartCommand() { 
    public void onCreate() { 
     Log.d(LOG_TAG, "onStartCommand"); 
     mgr = (SensorManager) getSystemService(SENSOR_SERVICE); 
     sensorList = mgr.getSensorList(Sensor.TYPE_ACCELEROMETER); 
     for (Sensor sensor : sensorList) { 
     mgr.registerListener(this, sensor, 
       SensorManager.SENSOR_DELAY_NORMAL); 
     } 
    } 

    @Override 
    public void onDestroy() { 
     Log.d(LOG_TAG, "onDestroy"); 
     mgr.unregisterListener(this);  
     super.onDestroy(); 
    } 

@Override 
public IBinder onBind(Intent arg0) { 
    // TODO Auto-generated method stub 
    return null; 
} 

@Override 
public void onAccuracyChanged(Sensor sensor, int accuracy) { 
    // TODO Auto-generated method stub  
} 

@Override 
public void onSensorChanged(SensorEvent event) { 
     Log.d(LOG_TAG, "onSensorChanged"); 
     StringBuilder builder = new StringBuilder(); 

     for (int i = 0; i < event.values.length; i++) { 
     builder.append(" ["); 
     builder.append(i); 
     builder.append("] = "); 
     builder.append(event.values[i]); 
     builder.append("\n"); 
     } 

     reading=builder.toString(); 

     //Send back reading to Activity 
     intent.putExtra("measurement", reading); 
     sendBroadcast(intent);   
} 

}

的Manifest.xml

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="com.practice" 
    android:versionCode="1" 
    android:versionName="1.0" > 
    <uses-sdk android:minSdkVersion="8" /> 
    <application 
     android:icon="@drawable/ic_launcher" 
     android:label="@string/app_name" > 
     <activity 
      android:name=".ServiceActivity" 
      android:label="@string/app_name" > 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 
       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 
     <service android:name=".SimpleService" ></service> 
    </application> 
</manifest> 

Answer 1

创建自定义意图：

final static String MY_ACTION = "com.practice.SimpleService.MY_ACTION"; 

在的Manifest.xml

<receiver android:name=".MyReceiver" android:enabled="true"> 
    <intent-filter> 
    <action android:name="com.practice.SimpleService.MY_ACTION"></action> 
    </intent-filter> 
</receiver> 

用于自定义发送的更多信息，请参阅Custom Intents and Broadcasting with Receivers