Android开发中的重力传感器用法实例详解

本文实例讲述了Android开发中的重力传感器用法。分享给大家供大家参考，具体如下：

重力传感器与方向传感器的开发步骤类似，只要理清了期中的x,y,z的值之后就可以根据他们的变化来进行编程了，首先来看一副图

假设当地的重力加速度值为g
当手机正面朝上的时候,z的值为q，反面朝上的时候，z的值为-g
当手机右侧面朝上的时候，x的值为g,右侧面朝上的时候,x的值为-g
当手机上侧面朝上的时候，y的值为g,右侧面朝上的时候,y的值为-g

了解了重力传感器中X,Y，Z的含义之后下面我们就开始学习如何使用

首先我们创建一个传感器管理器和一个传感器监听器，管理器用来管理传感器以及创建各种各样的传感器，监听器用来监视传感器的变化并且进行相应的操作

private SensorManager sensorManager;
private MySensorEventListener mySensorEventListener;
mySensorEventListener= new MySensorEventListener();//这个监听器当然是我们自己定义的，在重力感应器感应到手机位置有变化的时候，我们可以采取相应的操作，这里紧紧是将x,y,z的值打印出来
private final class MySensorEventListener implements SensorEventListener{
@Override
//可以得到传感器实时测量出来的变化值
public void onSensorChanged(SensorEvent event) {
//重力传感器
if(event.sensor.getType()==Sensor.TYPE_ACCELEROMETER){
float x = event.values[SensorManager.DATA_X];
float y = event.values[SensorManager.DATA_Y];
float z = event.values[SensorManager.DATA_Z];
//tv_accelerometer是界面上的一个TextView标签，不再赘述
tv_orientation.setText("Orientation:"+x+","+y+","+z);
}
}

我们在onResume()方法中创建重力传感器，并向系统注册监听器

protected void onResume() {
 Sensor sensor_accelerometer=sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
 sensorManager.registerListener(mySensorEventListener,sensor_accelerometer, SensorManager.SENSOR_DELAY_UI);
super.onResume();
}

最后我们在onPause()中注销所有传感器的监听，释放重力感应器资源!

protected void onPause() {
//注销所有传感器的监听
sensorManager.unregisterListener(mySensorEventListener);
super.onPause();
}

到此，有关重力传感器的介绍完毕!

接下来看一个Android用重力传感器做横竖屏切换的例子

在播放视频的时候，可能要做横竖屏的切换，但是，用户可以设置自己的手机关掉屏幕旋转，这个时候就需要想其他的办法了，比如：重力传感器。

public class ScreenSwitchUtils {
 private static final String TAG = ScreenSwitchUtils.class.getSimpleName();
 private volatile static ScreenSwitchUtils mInstance;
 private Activity mActivity;
 // 是否是竖屏
 private boolean isPortrait = true;
 private SensorManager sm;
 private OrientationSensorListener listener;
 private Sensor sensor;
 private SensorManager sm1;
 private Sensor sensor1;
 private OrientationSensorListener1 listener1;
 private Handler mHandler = new Handler() {
  public void handleMessage(Message msg) {
   switch (msg.what) {
   case 888:
    int orientation = msg.arg1;
    if (orientation > 45 && orientation < 135) {
    } else if (orientation > 135 && orientation < 225) {
    } else if (orientation > 225 && orientation < 315) {
     if (isPortrait) {
      Log.e(test, 切换成横屏);
      mActivity.setRequestedOrientation(0);
      isPortrait = false;
     }
    } else if ((orientation > 315 && orientation < 360) || (orientation > 0 && orientation < 45)) {
     if (!isPortrait) {
      Log.e(test,切换成竖屏);
      mActivity.setRequestedOrientation(1);
      isPortrait = true;
     }
    }
    break;
   default:
    break;
   }
  };
 };
 /** 返回ScreenSwitchUtils单例 **/
 public static ScreenSwitchUtils init(Context context) {
  if (mInstance == null) {
   synchronized (ScreenSwitchUtils.class) {
    if (mInstance == null) {
     mInstance = new ScreenSwitchUtils(context);
    }
   }
  }
  return mInstance;
 }
 private ScreenSwitchUtils(Context context) {
  Log.d(TAG, init orientation listener.);
  // 注册重力感应器,监听屏幕旋转
  sm = (SensorManager) context.getSystemService(Context.SENSOR_SERVICE);
  sensor = sm.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
  listener = new OrientationSensorListener(mHandler);
  // 根据 旋转之后/点击全屏之后 两者方向一致,激活sm.
  sm1 = (SensorManager) context.getSystemService(Context.SENSOR_SERVICE);
  sensor1 = sm1.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
  listener1 = new OrientationSensorListener1();
 }
 /** 开始监听 */
 public void start(Activity activity) {
  Log.d(TAG, start orientation listener.);
  mActivity = activity;
  sm.registerListener(listener, sensor, SensorManager.SENSOR_DELAY_UI);
 }
 /** 停止监听 */
 public void stop() {
  Log.d(TAG, stop orientation listener.);
  sm.unregisterListener(listener);
  sm1.unregisterListener(listener1);
 }
 /**
  * 手动横竖屏切换方向
  */
 public void toggleScreen() {
  sm.unregisterListener(listener);
  sm1.registerListener(listener1, sensor1,SensorManager.SENSOR_DELAY_UI);
  if (isPortrait) {
   isPortrait = false;
   // 切换成横屏
   mActivity.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
  } else {
   isPortrait = true;
   // 切换成竖屏
   mActivity.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
  }
 }
 public boolean isPortrait(){
  return this.isPortrait;
 }
 /**
  * 重力感应监听者
  */
 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) {
  }
  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) {
    // 屏幕旋转时
    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();
   }
  }
 }
 public class OrientationSensorListener1 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;
  public OrientationSensorListener1() {
  }
  public void onAccuracyChanged(Sensor arg0, int arg1) {
  }
  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) {
    // 屏幕旋转时
    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 (orientation > 225 && orientation < 315) {// 检测到当前实际是横屏
    if (!isPortrait) {
     sm.registerListener(listener, sensor,SensorManager.SENSOR_DELAY_UI);
     sm1.unregisterListener(listener1);
    }
   } else if ((orientation > 315 && orientation < 360) || (orientation > 0 && orientation < 45)) {// 检测到当前实际是竖屏
    if (isPortrait) {
     sm.registerListener(listener, sensor,SensorManager.SENSOR_DELAY_UI);
     sm1.unregisterListener(listener1);
    }
   }
  }
 }
}

使用的时候：

public class MainActivity extends Activity implements OnClickListener {
 private ScreenSwitchUtils instance;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  instance = ScreenSwitchUtils.init(this.getApplicationContext());
 }
 @Override
 protected void onStart() {
  super.onStart();
  instance.start(this);
 }
 @Override
 protected void onStop() {
  super.onStop();
  instance.stop();
 }
 @SuppressLint(NewApi)
 @Override
 public void onConfigurationChanged(Configuration newConfig) {
  super.onConfigurationChanged(newConfig);
  Log.e(test, onConfigurationChanged);
  if (instance.isPortrait()) {
   // 切换成竖屏
   LayoutParams params1 = new RelativeLayout.LayoutParams(screenWidth, DensityUtil.dip2px(this, 160));
   videoView.setLayoutParams(params1);
   Toast.makeText(getApplicationContext(), 竖屏, 0).show();
   Log.e(test, 竖屏);
  } else {
   // 切换成横屏
   LayoutParams params1 = new RelativeLayout.LayoutParams(screenHeight, screenWidth);
   videoView.setLayoutParams(params1);
   Toast.makeText(getApplicationContext(), 横屏, 0).show();
   Log.e(test, 横屏);
  }
 }
 @Override
 public void onClick(View arg0) {
  switch (arg0.getId()) {
  case R.id.iv_stretch:
   instance.toggleScreen();
   break;
  }
 }
}

调用了activity.setRequestedOrientation()以后，会触发activity.onConfigurationChanged();可以在这里面重新设置播放界面的大小。

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希望本文所述对大家Android程序设计有所帮助。