def stream_download(cookie, tokens, path):
url = '<STR_LIT>'.join([<EOL>const.PCS_URL_D,<EOL>'<STR_LIT>',<EOL>'<STR_LIT>', encoder.encode_uri_component(path),<EOL>'<STR_LIT>',<EOL>])<EOL>req = net.urlopen_without_redirect(url, headers=<EOL>{'<STR_LIT>': cookie.header_output()})<EOL>if req:<EOL><INDENT>return req<EOL><DEDENT>else:<EOL><INDENT>return None<EOL><DEDENT>
下载流媒体文件.

    path - 流文件的绝对路径.