摘要:线程是cpu可以调度的最小单元,多线程下载就是同时开启好几个线程同时下载。当服务器提供下载服务时,使用下载者是共享带宽的,在优先级相同的情况下,总服务器会对总下载线程进行平均分配。线程越多,下载速度越快.当前的下载软件都支持多线程技术。

　　通常服务器同时与多个用户连接，用户之间共享带宽。如果N个用户的优先级都相同，那么每个用户连接到该服务器上的实际带宽就是服务器带宽的N分之一。如果用户数目较多，则每个用户只能占有可怜的一点带宽，下载将会是个漫长的过程。

　　具体研究内容：下载功能实现，包括单线程下载功能，多线程下载功能，多任务下载功能，删除任务功能的实现；断点续传功能，包括下载过程中，暂停下载、继续上次未完成的下载任务。

关键词：多线程；线程安全；断点续传

Abstract:Thread is the smallest unit which cpu can schedule, Multithreading download is that open several threads simultaneously download.When the server is available for download, the use of those who download the shared bandwidth, evenly distributed in the same priority, the total server will download thread. The more threads, the faster the download speed download software to support multi-threading technology.

　　Usually server connection with multiple users to share bandwidth among users. If N users have the same priority, then each user connected to the actual bandwidth on the server is the one of N server bandwidth. If more number of users, each user can only occupy poor bandwidth, the download will be a lengthy process.

　　The specific research:Achieve the download function,including single-threaded download function, multi-threaded download function, download function of the multi-task, delete task functionality;Resuming downloads, including the download process, pause a download, and continue to the last unfinished download task.

Keywords: Multithreading; Thread security; Broken/Resume