Android利用Sensor(传感器)实现指南针小功能

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

package cn.roco.sensor; 
 
import android.app.Activity; 
import android.content.Context; 
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; 
 
public class MainActivity extends Activity { 
 
 private ImageView imageView; 
 
 /** 传感器管理器 */ 
 private SensorManager manager; 
 
 private SensorListener listener = new SensorListener(); 
 
 @Override 
 public void onCreate(Bundle savedInstanceState) { 
 super.onCreate(savedInstanceState); 
 setContentView(R.layout.main); 
 
 imageView = (ImageView) this.findViewById(R.id.imageView); 
 imageView.setKeepScreenOn(true);//屏幕高亮 
 //获取系统服务（SENSOR_SERVICE)返回一个SensorManager 对象 
 manager = (SensorManager) getSystemService(Context.SENSOR_SERVICE); 
 } 
 
 @Override 
 protected void onResume() { 
 /** 
  * 获取方向传感器 
  * 通过SensorManager对象获取相应的Sensor类型的对象 
  */ 
 Sensor sensor = manager.getDefaultSensor(Sensor.TYPE_ORIENTATION); 
 //应用在前台时候注册监听器 
 manager.registerListener(listener, sensor, 
  SensorManager.SENSOR_DELAY_GAME); 
 super.onResume(); 
 } 
 
 @Override 
 protected void onPause() { 
 //应用不在前台时候销毁掉监听器 
 manager.unregisterListener(listener); 
 super.onPause(); 
 } 
 
 private final class SensorListener implements SensorEventListener { 
 
 private float predegree = 0; 
 
 @Override 
 public void onSensorChanged(SensorEvent event) { 
  /** 
  * values[0]: x-axis 方向加速度 
  　　 values[1]: y-axis 方向加速度 
  　　 values[2]: z-axis 方向加速度 
  */ 
  float degree = event.values[0];// 存放了方向值 
  /**动画效果*/ 
  RotateAnimation animation = new RotateAnimation(predegree, degree, 
   Animation.RELATIVE_TO_SELF,0.5f,Animation.RELATIVE_TO_SELF,0.5f); 
  animation.setDuration(200); 
  imageView.startAnimation(animation); 
  predegree=-degree; 
  
  /** 
  float x=event.values[SensorManager.DATA_X]; 
  float y=event.values[SensorManager.DATA_Y]; 
  float z=event.values[SensorManager.DATA_Z]; 
  Log.i("XYZ", "x="+(int)x+",y="+(int)y+",z="+(int)z); 
  */ 
 } 
 
 @Override 
 public void onAccuracyChanged(Sensor sensor, int accuracy) { 
 
 } 
 
 } 
} 

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
 package="cn.roco.sensor" 
 android:versionCode="1" 
 android:versionName="1.0"> 
 <uses-sdk android:minSdkVersion="8" /> 
 
 <application android:icon="@drawable/icon" android:label="@string/app_name"> 
 <activity android:name="MainActivity" 
 android:label="@string/app_name"> 
 <intent-filter> 
 <action android:name="android.intent.action.MAIN" /> 
 <category android:name="android.intent.category.LAUNCHER" /> 
 </intent-filter> 
 </activity> 
 
 </application> 
</manifest>