根据MSDN自行封装的后台下载系统，// 模块名称：后台文件传输系统统// 模块功能：实现对后台文件传输系统的简单易懂包装，实现下载的功能 -According to the MSDN their own package downloaded in the background,// ​ ​ Module Name: background file transfer system, the system// module features: easy to underst