1、 While a thread is running, either uploading or downloading, you can query it to check on its status to provide the user with feedback (e.g. a progress bar).
当一个线程在运行的时候，不管是上传还是下载，你可以查询进程状态并且给用户一个反馈（例如一个进度条）。
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2、 Ditto for uploading from a file.
从文件上传也一样要复杂些。
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