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/
