让android程序根据重力感应旋转屏幕(支持4个方向旋转)

原文地址：http://blog.csdn.net/yixiaoqingyuz/article/details/6453798代码如下：

ChangeOrientationHandler.java

public class ChangeOrientationHandler extends Handler {
    private Activity activity;

    public ChangeOrientationHandler(Activity ac) {
        super();
        activity = ac;
    }

    @Override
    public void handleMessage(Message msg) {
        if (msg.what == 888) {
            int orientation = msg.arg1;
            if (orientation > 45 && orientation < 135) {
                activity.setRequestedOrientation(SCREEN_ORIENTATION_REVERSE_LANDSCAPE);
//                Log.d(MainActivity.TAG, "横屏翻转: ");
            } else if (orientation > 135 && orientation < 225) {
                activity.setRequestedOrientation(SCREEN_ORIENTATION_REVERSE_PORTRAIT);
//                Log.d(MainActivity.TAG, "竖屏翻转: ");
            } else if (orientation > 225 && orientation < 315) {
                activity.setRequestedOrientation(SCREEN_ORIENTATION_LANDSCAPE);
//                Log.d(MainActivity.TAG, "横屏: ");
            } else if ((orientation > 315 && orientation < 360) || (orientation > 0 && orientation < 45)) {
                activity.setRequestedOrientation(SCREEN_ORIENTATION_PORTRAIT);
//                Log.d(MainActivity.TAG, "竖屏: ");
            }
        }
        super.handleMessage(msg);
    }
}

OrientationSensorListener.java

public class OrientationSensorListener implements SensorEventListener {
    private static final int _DATA_X = 0;
    private static final int _DATA_Y = 1;
    private static final int _DATA_Z = 2;

    public static final int ORIENTATION_UNKNOWN = -1;

    private Handler rotateHandler;

    public OrientationSensorListener(Handler handler) {
        rotateHandler = handler;
    }

    public void onAccuracyChanged(Sensor arg0, int arg1) {
        // TODO Auto-generated method stub

    }

    public void onSensorChanged(SensorEvent event) {
        float[] values = event.values;
        int orientation = ORIENTATION_UNKNOWN;
        float X = -values[_DATA_X];
        float Y = -values[_DATA_Y];
        float Z = -values[_DATA_Z];
        float magnitude = X * X + Y * Y;
        // Don't trust the angle if the magnitude is small compared to the y value
        if (magnitude * 4 >= Z * Z) {
            float OneEightyOverPi = 57.29577957855f;
            float angle = (float) Math.atan2(-Y, X) * OneEightyOverPi;
            orientation = 90 - (int) Math.round(angle);
            // normalize to 0 - 359 range
            while (orientation >= 360) {
                orientation -= 360;
            }
            while (orientation < 0) {
                orientation += 360;
            }
        }

        if (rotateHandler != null) {
            rotateHandler.obtainMessage(888, orientation, 0).sendToTarget();
        }

    }
}

MainActivity.java

public class MainActivity extends AppCompatActivity {
    public static final String TAG = "MainActivity";
    private Button button;

    private Handler handler;
    private OrientationSensorListener listener;
    private SensorManager sm;
    private Sensor sensor;

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

        handler = new ChangeOrientationHandler(this);

        sm = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
        sensor = sm.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
        listener = new OrientationSensorListener(handler);
        sm.registerListener(listener, sensor, SensorManager.SENSOR_DELAY_UI);

        button = (Button) findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {

            public void onClick(View view) {
                Log.d(TAG, "onClick: " + getResources().getConfiguration().orientation);
            }
        });
    }

    @Override
    protected void onPause() {
        sm.unregisterListener(listener);
        super.onPause();
    }

    @Override
    protected void onResume() {
        sm.registerListener(listener, sensor, SensorManager.SENSOR_DELAY_UI);
        super.onResume();
    }
}