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Android開發(fā)中的重力傳感器用法實(shí)例詳解

更新時(shí)間：2017年11月02日 09:07:02 作者：東風(fēng)破

這篇文章主要介紹了Android開發(fā)中的重力傳感器用法,簡(jiǎn)單分析了Android重力傳感器的基本功能、使用方法,并結(jié)合實(shí)例形式分析了Android基于重力傳感器實(shí)現(xiàn)橫豎屏切換的相關(guān)操作技巧,需要的朋友可以參考下

本文實(shí)例講述了Android開發(fā)中的重力傳感器用法。分享給大家供大家參考，具體如下：

重力傳感器與方向傳感器的開發(fā)步驟類似，只要理清了期中的x,y,z的值之后就可以根據(jù)他們的變化來進(jìn)行編程了，首先來看一副圖

假設(shè)當(dāng)?shù)氐闹亓铀俣戎禐間
當(dāng)手機(jī)正面朝上的時(shí)候,z的值為q，反面朝上的時(shí)候，z的值為-g
當(dāng)手機(jī)右側(cè)面朝上的時(shí)候，x的值為g,右側(cè)面朝上的時(shí)候,x的值為-g
當(dāng)手機(jī)上側(cè)面朝上的時(shí)候，y的值為g,右側(cè)面朝上的時(shí)候,y的值為-g

了解了重力傳感器中X,Y，Z的含義之后下面我們就開始學(xué)習(xí)如何使用

首先我們創(chuàng)建一個(gè)傳感器管理器和一個(gè)傳感器監(jiān)聽器，管理器用來管理傳感器以及創(chuàng)建各種各樣的傳感器，監(jiān)聽器用來監(jiān)視傳感器的變化并且進(jìn)行相應(yīng)的操作

private SensorManager sensorManager;
private MySensorEventListener mySensorEventListener;
mySensorEventListener= new MySensorEventListener();//這個(gè)監(jiān)聽器當(dāng)然是我們自己定義的，在重力感應(yīng)器感應(yīng)到手機(jī)位置有變化的時(shí)候，我們可以采取相應(yīng)的操作，這里緊緊是將x,y,z的值打印出來
private final class MySensorEventListener implements SensorEventListener{
@Override
//可以得到傳感器實(shí)時(shí)測(cè)量出來的變化值
public void onSensorChanged(SensorEvent event) {
//重力傳感器
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是界面上的一個(gè)TextView標(biāo)簽，不再贅述
tv_orientation.setText("Orientation:"+x+","+y+","+z);
}
}

我們?cè)?code>onResume()方法中創(chuàng)建重力傳感器，并向系統(tǒng)注冊(cè)監(jiān)聽器

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

最后我們?cè)?code>onPause()中注銷所有傳感器的監(jiān)聽，釋放重力感應(yīng)器資源!

protected void onPause() {
//注銷所有傳感器的監(jiān)聽
sensorManager.unregisterListener(mySensorEventListener);
super.onPause();
}

到此，有關(guān)重力傳感器的介紹完畢!

接下來看一個(gè)Android用重力傳感器做橫豎屏切換的例子

在播放視頻的時(shí)候，可能要做橫豎屏的切換，但是，用戶可以設(shè)置自己的手機(jī)關(guān)掉屏幕旋轉(zhuǎn)，這個(gè)時(shí)候就需要想其他的辦法了，比如：重力傳感器。

public class ScreenSwitchUtils {
 private static final String TAG = ScreenSwitchUtils.class.getSimpleName();
 private volatile static ScreenSwitchUtils mInstance;
 private Activity mActivity;
 // 是否是豎屏
 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, 切換成橫屏);
      mActivity.setRequestedOrientation(0);
      isPortrait = false;
     }
    } else if ((orientation > 315 && orientation < 360) || (orientation > 0 && orientation < 45)) {
     if (!isPortrait) {
      Log.e(test,切換成豎屏);
      mActivity.setRequestedOrientation(1);
      isPortrait = true;
     }
    }
    break;
   default:
    break;
   }
  };
 };
 /** 返回ScreenSwitchUtils單例 **/
 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.);
  // 注冊(cè)重力感應(yīng)器,監(jiān)聽屏幕旋轉(zhuǎn)
  sm = (SensorManager) context.getSystemService(Context.SENSOR_SERVICE);
  sensor = sm.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
  listener = new OrientationSensorListener(mHandler);
  // 根據(jù) 旋轉(zhuǎn)之后/點(diǎn)擊全屏之后 兩者方向一致,激活sm.
  sm1 = (SensorManager) context.getSystemService(Context.SENSOR_SERVICE);
  sensor1 = sm1.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
  listener1 = new OrientationSensorListener1();
 }
 /** 開始監(jiān)聽 */
 public void start(Activity activity) {
  Log.d(TAG, start orientation listener.);
  mActivity = activity;
  sm.registerListener(listener, sensor, SensorManager.SENSOR_DELAY_UI);
 }
 /** 停止監(jiān)聽 */
 public void stop() {
  Log.d(TAG, stop orientation listener.);
  sm.unregisterListener(listener);
  sm1.unregisterListener(listener1);
 }
 /**
  * 手動(dòng)橫豎屏切換方向
  */
 public void toggleScreen() {
  sm.unregisterListener(listener);
  sm1.registerListener(listener1, sensor1,SensorManager.SENSOR_DELAY_UI);
  if (isPortrait) {
   isPortrait = false;
   // 切換成橫屏
   mActivity.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
  } else {
   isPortrait = true;
   // 切換成豎屏
   mActivity.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
  }
 }
 public boolean isPortrait(){
  return this.isPortrait;
 }
 /**
  * 重力感應(yīng)監(jiān)聽者
  */
 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) {
    // 屏幕旋轉(zhuǎn)時(shí)
    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) {
    // 屏幕旋轉(zhuǎn)時(shí)
    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) {// 檢測(cè)到當(dāng)前實(shí)際是橫屏
    if (!isPortrait) {
     sm.registerListener(listener, sensor,SensorManager.SENSOR_DELAY_UI);
     sm1.unregisterListener(listener1);
    }
   } else if ((orientation > 315 && orientation < 360) || (orientation > 0 && orientation < 45)) {// 檢測(cè)到當(dāng)前實(shí)際是豎屏
    if (isPortrait) {
     sm.registerListener(listener, sensor,SensorManager.SENSOR_DELAY_UI);
     sm1.unregisterListener(listener1);
    }
   }
  }
 }
}

使用的時(shí)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()) {
   // 切換成豎屏
   LayoutParams params1 = new RelativeLayout.LayoutParams(screenWidth, DensityUtil.dip2px(this, 160));
   videoView.setLayoutParams(params1);
   Toast.makeText(getApplicationContext(), 豎屏, 0).show();
   Log.e(test, 豎屏);
  } else {
   // 切換成橫屏
   LayoutParams params1 = new RelativeLayout.LayoutParams(screenHeight, screenWidth);
   videoView.setLayoutParams(params1);
   Toast.makeText(getApplicationContext(), 橫屏, 0).show();
   Log.e(test, 橫屏);
  }
 }
 @Override
 public void onClick(View arg0) {
  switch (arg0.getId()) {
  case R.id.iv_stretch:
   instance.toggleScreen();
   break;
  }
 }
}

調(diào)用了activity.setRequestedOrientation()以后，會(huì)觸發(fā)activity.onConfigurationChanged();可以在這里面重新設(shè)置播放界面的大小。

更多關(guān)于Android相關(guān)內(nèi)容感興趣的讀者可查看本站專題：《Android開發(fā)入門與進(jìn)階教程》、《Android視圖View技巧總結(jié)》、《Android編程之a(chǎn)ctivity操作技巧總結(jié)》、《Android操作SQLite數(shù)據(jù)庫技巧總結(jié)》、《Android操作json格式數(shù)據(jù)技巧總結(jié)》、《Android資源操作技巧匯總》及《Android控件用法總結(jié)》

希望本文所述對(duì)大家Android程序設(shè)計(jì)有所幫助。

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