轻松实现Android指南针功能

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

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;  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);    manager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);  }  @Override  protected void onResume() {    Sensor sensor = manager.getDefaultSensor(Sensor.TYPE_ORIENTATION);    manager.registerListener(listener, sensor,        SensorManager.SENSOR_DELAY_GAME);    super.onResume();  }  @Override  protected void onPause() {    manager.unregisterListener(listener);    super.onPause();  }  private final class SensorListener implements SensorEventListener {    private float predegree = 0;    public void onSensorChanged(SensorEvent event) {      float degree = event.values[0];// 存放了方向值 90      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;    }    public void onAccuracyChanged(Sensor sensor, int accuracy) {    }  }}