android 实现文件多线程下载的实例，只是下载的demo，文件下载还需要进行文件MD5校验、本地同步等操作才是能够保证文件下载的完整。-Android to achieve multi-threaded download instance, just download the demo file download also need to file MD5 validation, local synchronization and other operations is to ensure

串口实现发送指令数据，采用多线程编程 以读写文件方式操作串口，实现线程间同步- Serial port data transmission instruction, multi-threaded programming to read and write files serial manner, to achieve synchronization between threads