Python Flask 微信验证

@app.route('/check', methods=['GET', 'POST'])
def check():
    if request.method == 'GET':
        """微信Token验证"""
        signature = request.args.get('signature')
        timestamp = request.args.get('timestamp')
        nonce = request.args.get('nonce')
        echostr = request.args.get('echostr')
        token = 'zhanheng'

        items = [token, timestamp, nonce]
        items.sort()
        items_str = ''.join(items)

        sha1 = hashlib.sha1(items_str.encode('utf-8'))
        hashcode = sha1.hexdigest()
        if hashcode == signature:
            return echostr
        else:
            return ""

    if request.method == 'POST':
        """接收普通文本信息"""
        data = request.data
        root = ET.fromstring(data)
        xml_dict = {child.tag:child.text for child in root}
        xml = """<xml>
         <ToUserName><![CDATA[{FromUserName}]]></ToUserName>
         <FromUserName><![CDATA[{ToUserName}]]></FromUserName>
         <CreateTime>{CreateTime}</CreateTime>
         <MsgType><![CDATA[{MsgType}]]></MsgType>
         <Content><![CDATA[{Content}]]></Content>
         </xml>"""
        return xml.format(**xml_dict)