Android Compass Sensor 指南針 感應器

基本指南針感應器應用，需在實機上應用，如果手機無感應器，則LogCat會出現
 sensor or listener is null
1.加入圖片

2./res/layout/main.xml

3.Main.java

package tw.android;

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;
import android.widget.TextView;

public class Main extends Activity implements SensorEventListener {

 private ImageView image;
 // 初始角度
 private float currentDegree = 0f;
 // 感應器管理
 private SensorManager mSensorManager;

 private TextView tvHeading;

 float[] mGravity;
 float[] mGeomagnetic;
 float Rotation[] = new float[9];
 float[] degree = new float[3];

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);

  image = (ImageView) findViewById(R.id.imageViewCompass);
  tvHeading = (TextView) findViewById(R.id.tvHeading);
  mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
 }

 @Override
 protected void onResume() {
  super.onResume();

  // 註冊感應監聽器

  Sensor accelerometer = mSensorManager
    .getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
  Sensor magnetometer = mSensorManager
    .getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);

  mSensorManager.registerListener(this, accelerometer,
    SensorManager.SENSOR_DELAY_GAME);
  mSensorManager.registerListener(this, magnetometer,
    SensorManager.SENSOR_DELAY_GAME);
 }

 @Override
 protected void onPause() {
  super.onPause();

  // 停止感應監聽器
  mSensorManager.unregisterListener(this);
 }

 public void onSensorChanged(SensorEvent event) {

  if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {
   mGravity = event.values;
  }
  if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD) {
   mGeomagnetic = event.values;
  }
  if (mGravity != null && mGeomagnetic != null) {

   SensorManager.getRotationMatrix(Rotation, null, mGravity,
     mGeomagnetic);
   SensorManager.getOrientation(Rotation, degree);

   degree[0] = (float) Math.toDegrees(degree[0]);


   tvHeading.setText("Heading: " + (int) degree[0] + " degrees");

   // currentDegree-初始角度,-degree逆時針旋轉結束角度
   RotateAnimation ra = new RotateAnimation(currentDegree, -degree[0],
     Animation.RELATIVE_TO_SELF, 0.5f, // x座標
     Animation.RELATIVE_TO_SELF, 0.5f); // y座標

   // 轉動時間
   ra.setDuration(210);

   // 預設狀態結束後的動作設定
   ra.setFillAfter(true);

   // 將動作放入圖片
   image.startAnimation(ra);
   currentDegree = -degree[0];
  }
 }

 /* 改變經確度 */
 public void onAccuracyChanged(Sensor sensor, int accuracy) {
  // not in use
 }
}

檔案下載:
https://github.com/terryyamg/compassTest
參考來源:
http://www.javacodegeeks.com/2013/09/android-compass-code-example.html
http://www.codingforandroid.com/2011/01/using-orientation-sensors-simple.html