bs64name = base64.b64encode(name.encode('utf-8'))
注意此时bs64name为bytes类型，这就意味着得到的编码结果前带有 b，即b'xxxxxx'
base64 -----> 字符串bbs = str(base64.b64decode(bs64name), "utf-8")
此处做了转换，bbs为str类型
如果不想带b怎么办？bbs = str(base64.b64encode(name.encode("utf-8")), "utf-8")
