摘要:線程是cpu可以調度的最小單元,多線程下載就是同時開啟好幾個線程同時下載。當服務器提供下載服務時,使用下載者是共享帶寬的,在優先級相同的情況下,總服務器會對總下載線程進行平均分配。線程越多,下載速度越快.當前的下載軟件都支持多線程技術。

　　通常服務器同時與多個用戶連接，用戶之間共享帶寬。如果N個用戶的優先級都相同，那么每個用戶連接到該服務器上的實際帶寬就是服務器帶寬的N分之一。如果用戶數目較多，則每個用戶只能占有可憐的一點帶寬，下載將會是個漫長的過程。

　　具體研究內容：下載功能實現，包括單線程下載功能，多線程下載功能，多任務下載功能，刪除任務功能的實現；斷點續傳功能，包括下載過程中，暫停下載、繼續上次未完成的下載任務。

關鍵詞：多線程；線程安全；斷點續傳

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