https://www.cnblogs.com/LearningOnline/p/9885318.html
Content-Type请求头的作用,用于标记请求体数据的格式,如:
1. Content-Type:application/x-www-form-urlencoded请求体:b'pwd=123&user=root'2. Content-Type:application/json请求体:{"pwd": 123, "user": "root"}