android底层调用摄像头，并将摄像头采集的yuyv数据保存为rgb8，即256灰度图。android上面接口提供一个保存地址和名字，如"/Sdcard/rgb8.bmp"-android underlying call camera, and the camera acquisition yuyv data is saved as rgb8, that is 256 grayscale. android interface provides a preservation above addr