Python：如何从BaseHTTPRequestHandler HTTP POST处理程序获取键/值对？

def do_POST(self):    ctype, pdict = cgi.parse_header(self.headers.getheader('content-type'))    if ctype == 'multipart/form-data':        postvars = cgi.parse_multipart(self.rfile, pdict)    elif ctype == 'application/x-www-form-urlenpred':        length = int(self.headers.getheader('content-length'))        postvars = cgi.parse_qs(self.rfile.read(length), keep_blank_values=1)    else:        postvars = {}    ...