android gps杂乱分析

在上层调用locationManager.isProviderEnabled(android.location.LocationManager.GPS_PROVIDER))时返回了false，追了一下代码看看，以下是

在LocationManagerService.java中

private void _loadProvidersLocked() {        // Attempt to load "real" providers first        if(GpsLocationProvider.isSupported()){      //调试返回空，也就是说isSupported为false            // Create a gps location provider            GpsLocationProvider gpsProvider = new GpsLocationProvider(mContext, this);            mGpsStatusProvider = gpsProvider.getGpsStatusProvider();            mNetInitiatedListener = gpsProvider.getNetInitiatedListener();            addProvider(gpsProvider);            mGpsLocationProvider = gpsProvider;        }

GpsLocationProvider.isSupported()决定是否支持GPS，而这个方法实现在GpsLocationProvider.java中

 public static boolean isSupported() {        return native_is_supported();    }

向下就是调用JNI层的接口了，

{"native_is_supported", "()Z", (void*)android_location_GpsLocationProvider_is_supported},

static jboolean android_location_GpsLocationProvider_is_supported(JNIEnv* env, jclass clazz) {    return (sGpsInterface != NULL || get_gps_interface() != NULL);}


sGpsInterface是gps的接口，get_gps_interface()也是在这个文件中定义的，gps_get_interface函数属于HAL层的调用

 static const GpsInterface* get_gps_interface() {  int err;  hw_module_t* module;  const GpsInterface* interface = NULL;    err = hw_get_module(GPS_HARDWARE_MODULE_ID, (hw_module_t const**)&module);  if (err == 0) {    hw_device_t* device;    err = module->methods->open(module, GPS_HARDWARE_MODULE_ID, &device);    if (err == 0) {      gps_device_t* gps_device = (gps_device_t *)device;      interface = gps_device->get_gps_interface(gps_device);    }  }
get_gps_interface(devices)

未完

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