本文概要性地介绍如下内容

• 初始化过程

3，Sensor Client

• 初始化过程
• 与Server端通信的建立过程

4，应用开发总结

1，类架构框图

如上图所示，Sensor Framework相对于Audio等模块来说，比较简单，摘录几个关键类的设计意图如下：

/** * 
 * SensorManager lets you access the device's {
     @link android.hardware.Sensor * sensors}. Get an instance of this class by calling * {
     @link android.content.Context#getSystemService(java.lang.String) * Context.getSystemService()} with the argument * {
     @link android.content.Context#SENSOR_SERVICE}. * 
 * 
 * Always make sure to disable sensors you don't need, especially when your * activity is paused. Failing to do so can drain the battery in just a few * hours. Note that the system will not disable sensors automatically when * the screen turns off. * 
 * 
 * Note: Don't use this mechanism with a Trigger Sensor, have a look * at {
     @link TriggerEventListener}. {
     @link Sensor#TYPE_SIGNIFICANT_MOTION} * is an example of a trigger sensor. * 
 * 
 * public class SensorActivity extends Activity, implements SensorEventListener { *     private final SensorManager mSensorManager; *     private final Sensor mAccelerometer; * *     public SensorActivity() { *         mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE); *         mAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER); *     } * *     protected void onResume() { *         super.onResume(); *         mSensorManager.registerListener(this, mAccelerometer, SensorManager.SENSOR_DELAY_NORMAL); *     } * *     protected void onPause() { *         super.onPause(); *         mSensorManager.unregisterListener(this); *     } * *     public void onAccuracyChanged(Sensor sensor, int accuracy) { *     } * *     public void onSensorChanged(SensorEvent event) { *     } * } * 
 * * @see SensorEventListener * @see SensorEvent * @see Sensor * */public abstract class SensorManager {        ......}复制代码

/** * Sensor manager implementation that communicates with the built-in * system sensors. * * @hide */public class SystemSensorManager extends SensorManager {        ......}复制代码

class ISensorServer : public IInterface{public:    DECLARE_META_INTERFACE(SensorServer);     virtual Vector
    
      getSensorList(const String16& opPackageName) = 0;    virtual sp
     
       createSensorEventConnection(const String8& packageName,             int mode, const String16& opPackageName) = 0;    virtual int32_t isDataInjectionEnabled() = 0;};复制代码
     
    

/** * Every hardware module must have a data structure named HAL_MODULE_INFO_SYM * and the fields of this data structure must begin with hw_module_t * followed by module specific information. */struct sensors_module_t {
         struct hw_module_t common;     /**     * Enumerate all available sensors. The list is returned in "list".     * @return number of sensors in the list     */    int (*get_sensors_list)(struct sensors_module_t* module,            struct sensor_t const** list);    /**     *  Place the module in a specific mode. The following modes are defined     *     *  0 - Normal operation. Default state of the module.     *  1 - Loopback mode. Data is injected for the the supported     *      sensors by the sensor service in this mode.     * @return 0 on success     *         -EINVAL if requested mode is not supported     *         -EPERM if operation is not allowed     */    int (*set_operation_mode)(unsigned int mode);};复制代码

2，Sensor Server的初始化过程

3，Sensor Client

3.1 初始化过程

3.2 与Server端通信的建立过程

4，应用开发总结

其中SensorEventListener的定义摘录如下，更多应用层开发细节请参考google 官方文档。

/*** Used for receiving notifications from the SensorManager when* sensor values have changed.*/public interface SensorEventListener {   /**    * Called when sensor values have changed.    * 
See {
     @link android.hardware.SensorManager SensorManager}    * for details on possible sensor types.    * 
See also {
     @link android.hardware.SensorEvent SensorEvent}.    *     * 
NOTE: The application doesn't own the    * {
     @link android.hardware.SensorEvent event}    * object passed as a parameter and therefore cannot hold on to it.    * The object may be part of an internal pool and may be reused by    * the framework.    *    * @param event the {
     @link android.hardware.SensorEvent SensorEvent}.     */   public void onSensorChanged(SensorEvent event);   /**    * Called when the accuracy of the registered sensor has changed.    *    * 
See the SENSOR_STATUS_* constants in    * {
     @link android.hardware.SensorManager SensorManager} for details.    *    * @param accuracy The new accuracy of this sensor, one of    *         {
     @code SensorManager.SENSOR_STATUS_*}    */   public void onAccuracyChanged(Sensor sensor, int accuracy);}复制代码