status_t BnServiceManager::onTransact(
    uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags)
{
    //printf("ServiceManager received: "); data.print();
    switch(code) {
        case GET_SERVICE_TRANSACTION: {
            CHECK_INTERFACE(IServiceManager, data, reply);
            String16 which = data.readString16();
            sp<IBinder> b = const_cast<BnServiceManager*>(this)->getService(which);
            reply->writeStrongBinder(b);
            return NO_ERROR;
        } break;
        case CHECK_SERVICE_TRANSACTION: {
            CHECK_INTERFACE(IServiceManager, data, reply);
            String16 which = data.readString16();
            sp<IBinder> b = const_cast<BnServiceManager*>(this)->checkService(which);
            reply->writeStrongBinder(b);
            return NO_ERROR;
        } break;
        case ADD_SERVICE_TRANSACTION: {
            CHECK_INTERFACE(IServiceManager, data, reply);
            String16 which = data.readString16();
            sp<IBinder> b = data.readStrongBinder();
            status_t err = addService(which, b);  //沒有人來實現這個函式，根本不會呼叫到這個函式
            reply->writeInt32(err);
            return NO_ERROR;
        } break;
        case LIST_SERVICES_TRANSACTION: {
            CHECK_INTERFACE(IServiceManager, data, reply);
            Vector<String16> list = listServices();
            const size_t N = list.size();
            reply->writeInt32(N);
            for (size_t i=0; i<N; i++) {
                reply->writeString16(list[i]);
            }
            return NO_ERROR;
        } break;
        default:
            return BBinder::onTransact(code, data, reply, flags);
    }
}
 

（1）Android-5.0.2 binder涉及到三個程序client、server和ServiceManager。

（2）client、server用到了c++實現，也就是說用到了BpServiceManager這個類。

（3）ServiceManager只用到C語言實現，沒有用到c++實現，也就是說沒有使用BnServiceManager這個類。