Android4.4 GPS框架分析

GPS HAL层代码在目录trunk/Android/hardware/xxx/gps/skytraqskytraq_gsp.c，向下与硬件驱动通讯，向上提供接口GPS JNI层层代码在目录trunk/Android/frameworks/base/services/jni/com_android_server_location_GpsLocationProvider.cpp  C与java转换，给java层提供接口GPS framework层代码目录Android/frameworks/base/services/java/com/android/server下，主要文件是location服务对内部的封装并提供provider服务Android/frameworks/base/location/java/com/android/internal/location这个是framework对location服务内部的实现启动GPS服务代码流程如下public static void main(String[] args)-->ServerThread thr = new ServerThread();-->location = new LocationManagerService(context); -->ServiceManager.addService(Context.LOCATION_SERVICE, location);-->locationF.systemRunning()-->systemRunning()-->loadProvidersLocked();-->GpsLocationProvider gpsProvider = new GpsLocationProvider(mContext, this, mLocationHandler.getLooper());-->class_init_native();-->android_location_GpsLocationProvider_class_init_native(JNIEnv* env, jclass clazz) -->err = module->methods->open(module, GPS_HARDWARE_MODULE_ID, &device);-->pen_gps(const struct hw_module_t *module, char const *name, struct hw_device_t **device)-->sGpsInterface = gps_device->get_gps_interface(gps_device);-->const GpsInterface *gps__get_gps_interface(struct gps_device_t *dev)-->return &skytraqGpsInterface;-->GpsLocationProvider.isSupported()-->native_is_supported()-->android_location_GpsLocationProvider_is_supported(JNIEnv* env, jclass clazz)-->return (sGpsInterface != NULL);-->updateProvidersLocked-->updateProviderListenersLocked-->applyRequirementsLocked(provider);--> p.setRequest(providerRequest, worksource);-->public void setRequest(ProviderRequest request, WorkSource source)     --> sendMessage(SET_REQUEST, 0, new GpsRequest(request, source));    -->public void handleMessage(Message msg)    -->handleSetRequest(gpsRequest.request, gpsRequest.source);    -->startNavigating(singleShot);    -->native_set_position_mode(mPositionMode, GPS_POSITION_RECURRENCE_PERIODIC,interval, 0, 0)    -->native_start()Android系统运行的第一个进程就是init进程，在该进程中创建的第一个虚拟机就是zygote，zygote孵化的第一个虚拟机就是Dalvik,该进程就是SystemServer,对于的SystemServer代码是framework\base\services\java\com\android\server\SystemServer.java该SystemServer对于的第一个运行函数就是mainpublic static void main(String[] args) //SystemServer运行的第一个函数ServerThread thr = new ServerThread(); //初始化一个server线程 class ServerThread { public void initAndLoop()  {   if (!disableLocation) //开始的时候这里的 disableLocation = false   {              try{                     Slog.i(TAG, "Location Manager"); <1>                 location = new LocationManagerService(context); //实例化一个LocationManagerService服务，该服务主要用来管理GPS地理位置的变化                     ServiceManager.addService(Context.LOCATION_SERVICE, location); //将这个service添加到SystemManager中             }              catch (Throwable e)              {                reportWtf("starting Location Manager", e);             }             try {                    Slog.i(TAG, "Country Detector");                    countryDetector = new CountryDetectorService(context);//实例化一个CountryDetectorService服务，用来探测不同国家，也就是不同地区和时区                     ServiceManager.addService(Context.COUNTRY_DETECTOR, countryDetector);             } catch (Throwable e) {                    reportWtf("starting Country Detector", e);             }          }                  ActivityManagerService.self().systemReady(new Runnable()         {        public void run()         {        try         {<2>             if (locationF != null) locationF.systemRunning();//在<1>的位置已给locationF赋值，在这里调用LocationManagerService的systemRunning()函数            }             catch(Throwable e)             {               reportWtf("Notifying Location Service running", e);            }        }        }             }}接下来分析LocationManagerService(context)/**framework\base\services\java\com\android\server\LocationManagerService.java**/public class LocationManagerService extends ILocationManager.Stub{public void systemRunning() //该函数有<2>处调用{synchronized (mLock){/*GPS启动到运行及监听都在这两个函数里*/<3>loadProvidersLocked(); //在这里加载各种provider<4>updateProvidersLocked(); //加载后更新}}}/**framework\base\services\java\com\android\server\LocationManagerService.java**/private void loadProvidersLocked(){ // create a passive location provider, which is always enabled    PassiveProvider passiveProvider = new PassiveProvider(this);    addProviderLocked(passiveProvider);    mEnabledProviders.add(passiveProvider.getName());    mPassiveProvider = passiveProvider;    // Create a gps location provider<5> GpsLocationProvider gpsProvider = new GpsLocationProvider(mContext, this,            mLocationHandler.getLooper());<6> if (GpsLocationProvider.isSupported()) //这里调用JNI的函数接口     {        mGpsStatusProvider = gpsProvider.getGpsStatusProvider(); //获取gps状态provider        mNetInitiatedListener = gpsProvider.getNetInitiatedListener(); //初始网络监听         addProviderLocked(gpsProvider); //将gpsProvider添加到mProviders中        mRealProviders.put(LocationManager.GPS_PROVIDER, gpsProvider);    }}/**分析  <5>  ***/public class GpsLocationProvider implements LocationProviderInterface {static { class_init_native(); } //在这里调用JNI的android_location_GpsLocationProvider_class_init_native函数}static void android_location_GpsLocationProvider_class_init_native(JNIEnv* env, jclass clazz) {err = module->methods->open(module, GPS_HARDWARE_MODULE_ID, &device);//打开GPS设备文件，对应trunk/Android/hardware/xxx/gps/skytraq/skytraq_gps.c-->static int open_gps(const struct hw_module_t *module, char const *name, struct hw_device_t **device)//获取gpsInterface接口，该函数接口在trunk/Android/hardware/xxx/gps/skytraq/skytraq_gps.c中,对应的函数是gps__get_gps_interfacesGpsInterface = gps_device->get_gps_interface(gps_device);}const GpsInterface *gps__get_gps_interface(struct gps_device_t *dev){    return &skytraqGpsInterface;}/**分析 <6>  **/public static boolean GpsLocationProvider.isSupported(){return native_is_supported(); //该函数对应JNI的函数如下}static jboolean android_location_GpsLocationProvider_is_supported(JNIEnv* env, jclass clazz) {    return (sGpsInterface != NULL);}GpsLocationProvider.isSupported()返回true，所以会走if{}里面的。在网上查阅资料，都是基于2.3的系统，2.3的系统里是直接在isSupported()函数里来获取接口，没有在GpsLocationProvider类中实现调用class_init_native()来获取接口/**分析 <4> **//**framework\base\services\java\com\android\server\LocationManagerService.java**/private void updateProvidersLocked() {for (int i = mProviders.size() - 1; i >= 0; i--){boolean isEnabled = p.isEnabled(); //开始的时候返回falseboolean shouldBeEnabled = isAllowedByCurrentUserSettingsLocked(name); //在loadProvidersLocked()函数就说了，一直是enabled所以会走elseelse if (!isEnabled && shouldBeEnabled) {<7>      updateProviderListenersLocked(name, true, mCurrentUserId);         changesMade = true;     }}/*发送广播，app和framework都可以接受该广播*/if (changesMade) {            mContext.sendBroadcastAsUser(new Intent(LocationManager.PROVIDERS_CHANGED_ACTION),                    UserHandle.ALL);            mContext.sendBroadcastAsUser(new Intent(LocationManager.MODE_CHANGED_ACTION),                    UserHandle.ALL);  }}/**分析 <7>   framework\base\services\java\com\android\server\locationManagerService.java **/private void updateProviderListenersLocked(String provider, boolean enabled, int userId) {if (records != null){//这里主要是从UserHandle里解析UserId 是否等于 mCurrentUserId，如果是则发送notification给receiver  } if (enabled) //这里的 enabled == true{<8>  p.enable();     if (listeners > 0)      {<9>       applyRequirementsLocked(provider);     }  } else  {     p.disable();   }   }/**分析 <8>   framework\base\services\java\com\android\server\location\gpsLocationProvider.java**/public void enable() {synchronized (mLock) {   if (mEnabled) return;//开始的时候这里是false   mEnabled = true;     }<10>  sendMessage(ENABLE, 1, null);//发送消息}/**分析  <10>     base\services\java\com\android\server\location\gpsLocationProvider.java**/private void sendMessage(int message, int arg, Object obj) {        // hold a wake lock until this message is delivered        // note that this assumes the message will not be removed from the queue before        // it is handled (otherwise the wake lock would be leaked).        mWakeLock.acquire();<11>    mHandler.obtainMessage(message, arg, 1, obj).sendToTarget(); //通过handler机制来发送消息}/**分析  <11>     base\services\java\com\android\server\location\gpsLocationProvider.java**/private final class ProviderHandler extends Handler {public void handleMessage(Message msg) {switch (message) {    case ENABLE:  //有<10>可知，message == ENABLE ， msg.arg1 == 1        if (msg.arg1 == 1) {   <12>        handleEnable(); //所以会调用这个函数        } else {            handleDisable();        }        break;    .....    }}}/**分析  <12>     framework\base\services\java\com\android\server\location\gpsLocationProvider.java**/private void handleEnable() {<13>boolean enabled = native_init(); //调用JNI中的 static jboolean android_location_GpsLocationProvider_init(JNIEnv* env, jobject obj)  if (enabled)   {      mSupportsXtra = native_supports_xtra(); //native_supports_xtra()直接返回true，在class_init_native()已经赋值      if (mSuplServerHost != null)       {      /*这里没做任何事，因为sAGpsInterface为空，代码流程如下*/          native_set_agps_server(AGPS_TYPE_SUPL, mSuplServerHost, mSuplServerPort);          -->static void android_location_GpsLocationProvider_set_agps_server(JNIEnv* env, jobject obj, jint type, jstring hostname, jint port)          -->if (!sAGpsInterface) return;          -->sAGpsInterface = (const AGpsInterface*)sGpsInterface->get_extension(AGPS_INTERFACE);          -->static const void *skytraq_gps_get_extension(const char* name){    ALOGD("%s: called", __FUNCTION__);    return NULL;}      }      if (mC2KServerHost != null) { //同理这里也直接返回了          native_set_agps_server(AGPS_TYPE_C2K, mC2KServerHost, mC2KServerPort);      }  }else{      synchronized (mLock) {          mEnabled = false;      }      Log.w(TAG, "Failed to enable location provider");  }    }/**分析  <13>  framework\base\services\jni\com_android_server_location_GpsLocationProvider.cpp **/static jboolean android_location_GpsLocationProvider_init(JNIEnv* env, jobject obj){<14>if (!sGpsInterface || sGpsInterface->init(&sGpsCallbacks) != 0)//sGpsInterface不为null，在一开始的就已赋值，所以会调用init函数return false;.....}/**分析  <14>   hardware\xxx\gps\skytraq\Skytraq_gps.c **/static int skytraq_gps_init(GpsCallbacks* callbacks) //callbacks回调函数时有JNI传下来的，在JNI中实现的{GpsState*  s = &_gps_state; //该结构图数组初始化的时候都为0if (!s->init)<15>gps_state_init(s, callbacks);}/**分析  <15>   hardware\xxx\gps\skytraq\Skytraq_gps.c **/static void gps_state_init( GpsState*  state, GpsCallbacks* callbacks ){state->fd = gps_channel_open(GPS_CHANNEL_NAME);--> fd = open("/dev/skytraq_gps_ipc", O_RDWR |  O_SYNC); //打开串口int ret = ioctl(state->fd, GPS_IPC_SET, &gps_connect_info); //调用驱动函数ioctl设置gpsstate->thread = callbacks->create_thread_cb( "gps_state_thread", gps_state_thread, state );//创建线程，用来监听发送的命令和监听数据上报，}/**分析<9> frwmework\base\services\java\com\android\server\LocationManagerService.javaprivate void applyRequirementsLocked(String provider){//设置worksource和providerRequest.....<16>p.setRequest(providerRequest, worksource); //location provider 发送请求} /**分析<16> frwmework\base\services\java\com\android\server\location\GpsLocationProvider.java**/public void setRequest(ProviderRequest request, WorkSource source) {<17>   sendMessage(SET_REQUEST, 0, new GpsRequest(request, source)); //发送消息，SET_REQUEST == 3}/**分析<17> frwmework\base\services\java\com\android\server\location\GpsLocationProvider.java**/public void handleMessage(Message msg){...case SET_REQUEST:       GpsRequest gpsRequest = (GpsRequest) msg.obj;<18>   handleSetRequest(gpsRequest.request, gpsRequest.source);       break;}/**分析<18> frwmework\base\services\java\com\android\server\location\GpsLocationProvider.java**/private void handleSetRequest(ProviderRequest request, WorkSource source) {...<19>startNavigating(singleShot);//开始导航}/**分析<19> frwmework\base\services\java\com\android\server\location\GpsLocationProvider.java**/private void startNavigating(boolean singleShot){<20>native_set_position_mode(mPositionMode, GPS_POSITION_RECURRENCE_PERIODIC, interval, 0, 0)//该函数在HAL层直接返回了，没做任何事<21>native_start()} /**分析<20> framework\base\services\jni\com_android_server_location_GpsLocationProvider.cpp**/static jboolean android_location_GpsLocationProvider_set_position_mode(JNIEnv* env, jobject obj,        jint mode, jint recurrence, jint min_interval, jint preferred_accuracy, jint preferred_time){if (sGpsInterface)<22>        return (sGpsInterface->set_position_mode(mode, recurrence, min_interval, preferred_accuracy,                 preferred_time) == 0); //调用HAL层接口}/**分析<22> xxx\gps\skytraq\skytraq.gps.c**/static int skytraq_gps_set_position_mode(GpsPositionMode mode,                                      GpsPositionRecurrence recurrence,                                      uint32_t min_interval,                                      uint32_t preferred_accuracy,                                      uint32_t preferred_time){    ALOGD("%s: called", __FUNCTION__);    return 0;}/**分析<21> framework\base\services\jni\com_android_server_location_GpsLocationProvider.cpp**/static jboolean android_location_GpsLocationProvider_start(JNIEnv* env, jobject obj){if (sGpsInterface)<23>return (sGpsInterface->start() == 0); //调用HAL 层的static int skytraq_gps_start()}/**分析<23> xxx\gps\skytraq\skytraq.gps.c**/static int skytraq_gps_start(){gps_state_start(s);-->s->status = CMD_START;   /*在<15>线程函数gps_state_thread()中while(1)中等该命令，进入获取数据*/}此时GPS就已运行
为了保密，只好用xxx来代替
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