10.11 传感器专题(2)——方向传感器

is(context, null); } public CompassView(Context context, AttributeSet attrs) { super(context, attrs); sWidth = ScreenUtil.getScreenW(context); sHeight = ScreenUtil.getScreenH(context); init(); new Thread(this).start(); } public CompassView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } private void init() { mTextPaint = new Paint(); mTextPaint.setColor(Color.GRAY); mTextPaint.setTextSize(64); mTextPaint.setStyle(Paint.Style.FILL); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); canvas.drawText(msg, sWidth / 4 , sWidth / 2, mTextPaint); } // 更新指南针角度 public void setDegree(float degree) { // 设置灵敏度 if(Math.abs(dec - degree) >= 2 ) { dec = degree; int range = 22; String degreeStr = String.valueOf(dec); // 指向正北 if(dec > 360 - range && dec < 360 + range) { msg = "正北 " + degreeStr + "°"; } // 指向正东 if(dec > 90 - range && dec < 90 + range) { msg = "正东 " + degreeStr + "°"; } // 指向正南 if(dec > 180 - range && dec < 180 + range) { msg = "正南 " + degreeStr + "°"; } // 指向正西 if(dec > 270 - range && dec < 270 + range) { msg = "正西 " + degreeStr + "°"; } // 指向东北 if(dec > 45 - range && dec < 45 + range) { msg = "东北 " + degreeStr + "°"; } // 指向东南 if(dec > 135 - range && dec < 135 + range) { msg = "东南 " + degreeStr + "°"; } // 指向西南 if(dec > 225 - range && dec < 225 + range) { msg = "西南 " + degreeStr + "°"; } // 指向西北 if(dec > 315 - range && dec < 315 + range) { msg = "西北 " + degreeStr + "°"; } } } @Override public void run() { while(!Thread.currentThread().isInterrupted()) { try { Thread.sleep(100); } catch(InterruptedException e) { Thread.currentThread().interrupt(); } postInvalidate(); } }}MainActivity.java：public class MainActivity extends AppCompatActivity implements SensorEventListener { private CompassView cView; private SensorManager sManager; private Sensor mSensorOrientation; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); cView = new CompassView(MainActivity.this); sManager = (SensorManager) getSystemService(SENSOR_SERVICE); mSensorOrientation = sManager.getDefaultSensor(Sensor.TYPE_ORIENTATION); sManager.registerListener(this, mSensorOrientation, SensorManager.SENSOR_DELAY_UI); setContentView(cView); } @Override public void onSensorChanged(SensorEvent event) { cView.setDegree(event.values[0]); } @Override public void onAccuracyChanged(Sensor sensor, int accuracy) { } @Override protected void onDestroy() { super.onDestroy(); sManager.unregisterListener(this); }}这就是一个很简单的指南针的雏形了，有兴趣的可以自己绘制个罗盘和指针，然后实现一个好看的指南针~5.本节示例代码下载：SensorDemo2.zipSensorDemo3.zip本节小结：好的，本节给大家介绍了Android中最常用的方向传感器，以及他的简单用法，以及写了一个指南针的例子，而完成指南针我们只用到一个values[0]的值，利用其他两个值我们还可以用来测量某地是否平躺，即制作水平尺，有空的可以写个来玩玩~好的，就到这里，谢谢~