Android实现电子罗盘(指南针)方向传感器的应用

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
  android:layout_width="match_parent" 
  android:layout_height="match_parent" 
  android:orientation="vertical"  
  android:gravity="center" 
  > 
  <ImageView 
    android:id="@+id/compass_imageView" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:src="@drawable/compass" /> 
</LinearLayout> 

import android.app.Activity; 
import android.hardware.Sensor; 
import android.hardware.SensorEvent; 
import android.hardware.SensorEventListener; 
import android.hardware.SensorManager; 
import android.os.Bundle; 
import android.view.animation.Animation; 
import android.view.animation.RotateAnimation; 
import android.widget.ImageView; 
/** 
 * 电子罗盘 方向传感器 
 */ 
public class ComPassActivity extends Activity implements SensorEventListener { 
  private ImageView imageView; 
  private float currentDegree = 0f; 
  public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.compass); 
    imageView = (ImageView) findViewById(R.id.compass_imageView); 
    // 传感器管理器 
    SensorManager sm = (SensorManager) getSystemService(SENSOR_SERVICE); 
    // 注册传感器(Sensor.TYPE_ORIENTATION(方向传感器);SENSOR_DELAY_FASTEST(0毫秒延迟); 
    // SENSOR_DELAY_GAME(20,000毫秒延迟)、SENSOR_DELAY_UI(60,000毫秒延迟)) 
    sm.registerListener(ComPassActivity.this, 
        sm.getDefaultSensor(Sensor.TYPE_ORIENTATION), 
        SensorManager.SENSOR_DELAY_FASTEST); 
  } 
  //传感器报告新的值(方向改变) 
  public void onSensorChanged(SensorEvent event) { 
    if (event.sensor.getType() == Sensor.TYPE_ORIENTATION) { 
      float degree = event.values[0]; 
      /* 
      RotateAnimation类：旋转变化动画类 
      参数说明: 
      fromDegrees：旋转的开始角度。 
      toDegrees：旋转的结束角度。 
      pivotXType：X轴的伸缩模式，可以取值为ABSOLUTE、RELATIVE_TO_SELF、RELATIVE_TO_PARENT。 
      pivotXValue：X坐标的伸缩值。 
      pivotYType：Y轴的伸缩模式，可以取值为ABSOLUTE、RELATIVE_TO_SELF、RELATIVE_TO_PARENT。 
      pivotYValue：Y坐标的伸缩值 
      */ 
      RotateAnimation ra = new RotateAnimation(currentDegree, -degree, 
          Animation.RELATIVE_TO_SELF, 0.5f, 
          Animation.RELATIVE_TO_SELF, 0.5f); 
      //旋转过程持续时间 
      ra.setDuration(200); 
      //罗盘图片使用旋转动画 
      imageView.startAnimation(ra); 
      currentDegree = -degree; 
    } 
  } 
  //传感器精度的改变 
  public void onAccuracyChanged(Sensor sensor, int accuracy) { 
  } 
}