線程類並將信息傳遞給主活動類到TextView中

Question

我想使onSenzorChange方法運行到線程中。 運行更平穩。 並隨時獲取x軸信息。 並將其傳遞給TextView的主類（活動）。

MainActivity類：

public class MainActivity extends AppCompatActivity {
    TextView textView;
    TestOfPassUIThread t;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = (TextView) findViewById(R.id.textView);

        t = new TestOfPassUIThread(this);
    }
    public void onStart(View view) {
        t.register();
    }
}

TestOfPassUIThread類（不是活動或任何東西）

public class TestOfPassUIThread implements SensorEventListener {

    private SensorManager sensorManager;
    private Sensor sensor;

    public TestOfPassUIThread (Context context) {
        sensorManager = (SensorManager) context.getSystemService(Context.SENSOR_SERVICE);
        sensor = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
    }
    public void register(){
        sensorManager.registerListener(this, sensor, SensorManager.SENSOR_DELAY_NORMAL);
    }
    public void unregister() {
        sensorManager.unregisterListener(this);
    }
    // Want this method be in Thread
    //How can I do this ?
    @Override
    public void onSensorChanged(SensorEvent event) {
        float xAxis = event.values[0];
        // And I want it to display in TextView!
        // In main activity would be textView.setText("" + xAxis);
        //How to pass it to MainActivity class ?
    }
    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {

    }
}

Answer 1

有多種方法可以在textview上書寫，以下是一種方法。 （您可能想閱讀有關回調的信息，請參閱如何在Java中實現回調 ）。

至於從后台訪問UI線程，也有多種方法可以執行此操作（檢查： 從另一個線程在主線程中運行代碼 ）。

關於我們為什么在下面使用HandlerThread原因，您可以在這里閱讀： 單獨線程中的加速度傳感器 。

因此，您的聽眾變成：

public abstract class TestOfPassUIThread implements SensorEventListener {

    private SensorManager   sensorManager;
    private Sensor          sensor;
    private HandlerThread   handlerThread;
    private Context         context;
    private Runnable        uiRunnable;

    private float           xAxis;

    public TestOfPassUIThread (Context context) {
        this.context    = context;
        sensorManager   = (SensorManager) context.getSystemService (Context.SENSOR_SERVICE);
        sensor          = sensorManager.getDefaultSensor (Sensor.TYPE_ACCELEROMETER);
    }

    public void register () {
        initUiRunnable ();

        handlerThread   = new HandlerThread ("sensorHandler");
        handlerThread.start ();

        sensorManager.registerListener (
            this,
            sensor,
            SensorManager.SENSOR_DELAY_NORMAL,
            new Handler (handlerThread.getLooper ())
        );
    }

    public void unregister () {
        sensorManager.unregisterListener (this);

        try {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2) {
                handlerThread.quitSafely ();
                return;
            }
            handlerThread.quit ();
        } finally {
            uiRunnable = null;
        }
    }

    @Override
    public void onSensorChanged (SensorEvent event) {
        xAxis = event.values [0];

        // your other background operations

        ((Activity)context).runOnUiThread (uiRunnable);

        // your other background operations
    }

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

    }

    private void initUiRunnable () {
        uiRunnable = new Runnable () {

            @Override
            public void run () {
                // ...... your other UI operations

                fillTextView (xAxis);

                // ...... your other UI operations
            }
        };
    }

    public abstract void fillTextView (float xAxis);
}

您的活動：

public class MainActivity extends AppCompatActivity {

    private TextView           textView;
    private TestOfPassUIThread t;

    @Override
    protected void onCreate (Bundle savedInstanceState) {
        super.onCreate (savedInstanceState);
        setContentView (R.layout.activity_main);

        textView = (TextView)findViewById (R.id.textView);

        t = new TestOfPassUIThread (this) {

            @Override
            public void fillTextView (float xAxis) {
                textView.setText ("Current xAxis: " + xAxis);
            }
        };
    }

    @Override
    protected void onResume () {
        super.onResume ();
        t.register ();
    }

    @Override
    protected void onPause () {
        t.unregister ();
        super.onPause ();
    }
}

另外，當您覆蓋Activity的LifeCycle方法（例如onStart ， onResume等）時，請確保調用super.lifeCycleMethod 。

---