cs.get()->*fnConnectService 表達的意義

以下代碼，一直不明白標紅的地方的意義

const sp<::android::hardware::ICameraService> cs = getCameraService();

 if (cs != 0) {
        TCamConnectService fnConnectService = TCamTraits::fnConnectService;
        status = (cs.get()->*fnConnectService)(cl, cameraId, clientPackageName, clientUid,
                                             /*out*/ c->mCamera);
    }

BpServiceManager(BpBinder(0))的對象

http://www.javashuo.com/article/p-zeienxqg-kc.html

template <typename TCam, typename TCamTraits>
const sp<::android::hardware::ICameraService> CameraBase<TCam, TCamTraits>::getCameraService()
{
    Mutex::Autolock _l(gLock);
    if (gCameraService.get() == 0) {
        char value[PROPERTY_VALUE_MAX];
        property_get("config.disable_cameraservice", value, "0");
        if (strncmp(value, "0", 2) != 0 && strncasecmp(value, "false", 6) != 0) {
            return gCameraService;
        }

        sp<IServiceManager> sm = defaultServiceManager();
        sp<IBinder> binder;
        do {
            binder = sm->getService(String16(kCameraServiceName));
            if (binder != 0) {
                break;
            }
            ALOGW("CameraService not published, waiting...");
            usleep(kCameraServicePollDelay);
        } while(true);
        if (gDeathNotifier == NULL) {
            gDeathNotifier = new DeathNotifier();
        }
        binder->linkToDeath(gDeathNotifier);
        gCameraService = interface_cast<::android::hardware::ICameraService>(binder);
    }
    ALOGE_IF(gCameraService == 0, "no CameraService!?");
    return gCameraService;
}

getCameraService最終獲得的是一個BpCameraService(BpBinder(handle))實例，在BpCameraService中實現了對CameraService端的方法封裝。

其相關代碼:

class BpCameraService: public BpInterface<ICameraService>
{
public:
    explicit BpCameraService(const sp<IBinder>& impl)
        : BpInterface<ICameraService>(impl)
    {
    }

。。。

}

回頭再看

const sp<::android::hardware::ICameraService> cs = getCameraService();

cs.get() 其實是class sp 中的get方法

inline  T*      get() const         { return m_ptr; }

能夠理解爲 cs.get返回一個指向ICameraService的對象