onerror的return true和false，确实onerror是个很优待考究的地方，
另外要说的
/**
* Sets the data source (file-path or http/rtsp URL) to use.
*
* @param path the path of the file, or the http/rtsp URL of the stream you want to play
* @throws IllegalStateException if it is called in an invalid state
*/
public native void setDataSource(String path) throws IOException, IllegalArgumentException, IllegalStateException;
/**
* Sets the data source (FileDescriptor) to use. It is the caller's responsibility
* to close the file descriptor. It is safe to do so as soon as this call returns.
*
* @param fd the FileDescriptor for the file you want to play
* @throws IllegalStateException if it is called in an invalid state
*/
public void setDataSource(FileDescriptor fd)
throws IOException, IllegalArgumentException, IllegalStateException {
// intentionally less than LONG_MAX
setDataSource(fd, 0, 0x7ffffffffffffffL);
}
从效果上来看如果把手机内存的通过流的方式设置datasource就会跑到onerror（4，-4）
