public boolean transact(int code, Parcel data, Parcel reply, int flags) throws RemoteException {
        Binder.checkParcel(this, code, data, "Unreasonably large binder buffer");
        if (Binder.isTracingEnabled()) { Binder.getTransactionTracker().addTrace(); }
        return transactNative(code, data, reply, flags);
}

public native boolean transactNative(int code, Parcel data, Parcel reply, int flags) throws RemoteException;

transactNative方法对应于android_os_BinderProxy_transact。这个可以从register_android_os_Binder中的int_register_android_os_BinderProxy方法中的方法映射可以看出。