Android传感器之-方向传感器Orientation功能实现与源码

先明确一下空间坐标系的三个方向：
x 方向就是手机的水平方向，右为正；
y 方向就是手机的水平垂直方向，前为正；
z 方向就是手机的空间垂直方向，天空的方向为正，地球的方向为负。
方向角的定义是手机y轴 水平面上的投影 与 正北方向的夹角。 （值得范围是 0 ~ 359 其中0=North, 90=East, 180=South, 270=West）
倾斜角的定义是手机y轴 与水平面的夹角 （手机z轴向y轴方向移动为正 ,值得范围是 -180 ~ 180）
旋转角的定义是手机x轴 与水平面的夹角 （手机x轴离开z轴方向为正， 值得范围是 -90 ~ 90）
也就是说，当你把手机水平放置在桌面上(屏幕向上)且手机指向正北(Y轴方向)，此时传感器获得的xyz三个值应该都为0。

基于Rexsee对于方向传感器Orientation的扩展，我们可以很快的实现传感器功能，比如读取X/Y/Z方向角度值：rexseeOrientation.getLastKnownX()；读取响应速度：rexseeOrientation.getRate()；设置传感器检测周期：rexseeOrientation.setCycle(1000)等。具体的函数介绍可以在Rexsee社区的手册与源码中查阅：http://www.rexsee.com/CN/helpReference.php

如下是Rexsee用Java封装的的方向传感器功能详细源码。感兴趣的也可以直接去Rexsee社区查阅：http://www.rexsee.com。
但是首先需要知道，并不是所有的Android手机都支持方向传感器。。比如说乐Phone，好像就是加速度、重力和光线，方向和磁场貌似都不支持。

/* 
* Copyright (C) 2011 The Rexsee Open Source Project 
* 
* Licensed under the Rexsee License, Version 1.0 (the "License"); 
* you may not use this file except in compliance with the License. 
* You may obtain a copy of the License at 
* 
*      http://www.rexsee.com/CN/legal/license.html 
* 
* Unless required by applicable law or agreed to in writing, software 
* distributed under the License is distributed on an "AS IS" BASIS, 
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
* See the License for the specific language governing permissions and 
* limitations under the License. 
*/ 
 
package rexsee.sensor;  
 
import rexsee.core.browser.JavascriptInterface;  
import rexsee.core.browser.RexseeBrowser;  
import android.content.Context;  
import android.hardware.Sensor;  
import android.hardware.SensorEvent;  
import android.hardware.SensorEventListener;  
import android.hardware.SensorManager;  
 
public class RexseeSensorOrientation implements JavascriptInterface {  
 
       public static final String INTERFACE_NAME = "Orientation";  
       @Override  
       public String getInterfaceName() {  
               return mBrowser.application.resources.prefix + INTERFACE_NAME;  
       }  
       @Override  
       public JavascriptInterface getInheritInterface(RexseeBrowser childBrowser) {  
               return this;  
       }  
       @Override  
       public JavascriptInterface getNewInterface(RexseeBrowser childBrowser) {  
               return new RexseeSensorOrientation(childBrowser);  
       }  
 
       public static final String EVENT_ONORIENTATIONCHANGED = "onOrientationChanged";  
 
       private final Context mContext;  
       private final RexseeBrowser mBrowser;  
       private final SensorManager mSensorManager;  
       private SensorEventListener mSensorListener;  
       private final Sensor mSensor;  
 
       private int mRate = SensorManager.SENSOR_DELAY_NORMAL;  
       private int mCycle = 100; //milliseconds  
       private int mEventCycle = 100; //milliseconds  
 
       private float mAccuracyX = 0;  
       private float mAccuracyY = 0;  
       private float mAccuracyZ = 0;  
 
       private long lastUpdate = -1;  
       private long lastEvent = -1;  
 
       private float x = -999f;  
       private float y = -999f;  
       private float z = -999f;  
 
       public RexseeSensorOrientation(RexseeBrowser browser) {  
               mContext = browser.getContext();  
               mBrowser = browser;  
               browser.eventList.add(EVENT_ONORIENTATIONCHANGED);  
 
               mSensorManager = (SensorManager) mContext.getSystemService(Context.SENSOR_SERVICE);  
 
               mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION);  
               mSensorListener = new SensorEventListener() {  
                       @Override  
                       public void onAccuracyChanged(Sensor sensor, int accuracy) {  
                       }  
                       @Override  
                       public void onSensorChanged(SensorEvent event) {  
                               if (event.sensor.getType() != Sensor.TYPE_ORIENTATION) return;  
                               long curTime = System.currentTimeMillis();  
                               if (lastUpdate == -1 || (curTime - lastUpdate) > mCycle) {  
                                       lastUpdate = curTime;  
                                       float lastX = x;  
                                       float lastY = y;  
                                       float lastZ = z;  
                                       x = event.values[SensorManager.DATA_X];  
                                       y = event.values[SensorManager.DATA_Y];  
                                       z = event.values[SensorManager.DATA_Z];  
                                       if (lastEvent == -1 || (curTime - lastEvent) > mEventCycle) {  
                                               if (  
                                                               (mAccuracyX >= 0 && Math.abs(x - lastX) > mAccuracyX)  
                                                                               || (mAccuracyY >= 0 && Math.abs(y - lastY) > mAccuracyY)  
                                                                               || (mAccuracyZ >= 0 && Math.abs(z - lastZ) > mAccuracyZ)  
                                                       ) {  
                                                               lastEvent = curTime;  
                                                               mBrowser.eventList.run(EVENT_ONORIENTATIONCHANGED);  
                                                       }  
                                               }  
                                       }  
                               }  
               };  
 
       }  
 
       public String getLastKnownX() {  
               return (x == -999) ? "null" : String.valueOf(x);  
       }  
       public String getLastKnownY() {  
               return (y == -999) ? "null" : String.valueOf(y);  
       }  
       public String getLastKnownZ() {  
               return (z == -999) ? "null" : String.valueOf(z);  
       }  
 
       public void setRate(String rate) {  
               mRate = SensorRate.getInt(rate);  
       }  
       public String getRate() {  
               return SensorRate.getString(mRate);  
       }  
       public void setCycle(int milliseconds) {  
               mCycle = milliseconds;  
       }  
       public int getCycle() {  
               return mCycle;  
       }  
       public void setEventCycle(int milliseconds) {  
               mEventCycle = milliseconds;  
       }  
       public int getEventCycle() {  
               return mEventCycle;  
       }  
       public void setAccuracy(float x, float y, float z) {  
               mAccuracyX = x;  
               mAccuracyY = y;  
               mAccuracyZ = z;  
       }  
       public float getAccuracyX() {  
               return mAccuracyX;  
       }  
       public float getAccuracyY() {  
               return mAccuracyY;  
       }  
       public float getAccuracyZ() {  
               return mAccuracyZ;  
       }  
 
       public boolean isReady() {  
               return (mSensor == null) ? false : true;  
       }  
       public void start() {  
               if (isReady()) {  
                       mSensorManager.registerListener(mSensorListener, mSensor, mRate);  
               } else {  
                       mBrowser.exception(getInterfaceName(), "Orientation sensor is not found.");  
               }  
       }  
       public void stop() {  
               if (isReady()) {  
                       mSensorManager.unregisterListener(mSensorListener);  
               }  
       }  
 
}

仅对Rexsee的源码和函数事件做了整理，相关的demo或源码解析可以在Rexsee社区了解，目前Rexsee已提供了近2000个扩展，覆盖Android原生功能超过90%，且全部开放：  http://www.rexsee.com/