android 中传感器的后台服务

Question

我已经实现了一个代码，当我们摇动我们的设备时打开一个应用程序。就我将所有代码保存到 MainActivity and 而没有任何后台服务而言，一切进展顺利。但是当我尝试添加后台服务时它不起作用，因为 我希望它继续工作而不必每次都进入应用程序。 所以有人可以建议我我在做什么 wrong.Thanks ！

BackgroundService.java

public class BackgroundService extends Service implements SensorEventListener {

    public BackgroundService() {
    }
    private SensorManager mSensorManager;
    private Sensor mSensor;
    private long lastUpdate = 0;
    private float last_x, last_y, last_z;
    private static final int SHAKE_THRESHOLD = 600;


    @Override
    public void onCreate() {
        super.onCreate();

        // Get sensor manager on starting the service.
        mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);

        // Registering...
        mSensorManager.registerListener(this, mSensor, SensorManager.SENSOR_DELAY_NORMAL);

        // Get default sensor type
        mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {

        // Get sensor manager on starting the service.
        mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);

        // Registering...
        mSensorManager.registerListener(this, mSensor, SensorManager.SENSOR_DELAY_NORMAL);

        // Get default sensor type
        mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);

        return START_STICKY;

    }

    @Override
    public IBinder onBind(Intent intent) {
        throw new UnsupportedOperationException("Not Yet Implemented");
    }

    @Override
    public void onSensorChanged(SensorEvent sensorEvent) {

        mSensorManager.registerListener(this, mSensor, SensorManager.SENSOR_DELAY_NORMAL);

        Sensor mySensor = sensorEvent.sensor;

        mSensorManager.registerListener(this, mySensor, SensorManager.SENSOR_DELAY_NORMAL);

        if (mySensor.getType() == Sensor.TYPE_ACCELEROMETER) {

            float[] values = sensorEvent.values;
            float x = values[0];
            float y = values[1];
            float z = values[2];

            long curTime = System.currentTimeMillis();
            if ((curTime - lastUpdate) > 100) {
                long diffTime = (curTime - lastUpdate);
                lastUpdate = curTime;
                float speed
                        = Math.abs(x + y + z - last_x - last_y - last_z) / diffTime * 10000;
                if (speed > SHAKE_THRESHOLD) {
                    openWhatsApp();
                }
                last_x = x;
                last_y = y;
                last_z = z;
            }
            // Stop the sensor and service
               mSensorManager.unregisterListener(this);
               stopSelf();
        }
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int i) {
    }


    public void openWhatsApp() {
        Intent launchIntent = getPackageManager().getLaunchIntentForPackage("com.whatsapp");
        if (launchIntent != null) {
            startService(launchIntent);
        }
    }

}

MainActivity.java

public class MainActivity 扩展 AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        Intent i = new Intent(MainActivity.this, BackgroundService.class);
        startService(i);
    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="joshipinak.com.shakeshooksaken">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name"
            android:theme="@style/AppTheme.NoActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>

        </activity>
        <service android:name=".BackgroundService" />
    </application>

</manifest>

Answer 1

在GitHub Android Examples中有一个完整的应用程序。它使用像您的代码一样的命令模式来检查传感器值和 AlarmManager.

在中是一个使用SensorEventListener界面的例子。

Android 开发者网站说要在 this page 上使用 IntentService。您还可以在 this question on SO.

中阅读 Service 和 IntentService 之间的区别

这些链接也可能对您有所帮助：

A question on SO about having an Android app running in the background
Duplicate of previous link with other information
SO question about communication between Activity and Service

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