Tornado构建RESTful应用

RESTful

• Representational State Transfer：表中状态转移
• 资源(Resources),表现层(Representation),状态转化(State Transfer)

RESTful风格

• Resources(资源)：使用URI指向的一个实体
• Representation(表现层)：资源的表现形式，比如图片、HTML文本等
• State Transfer(转态转化)：GET、POST、PUT、DELETE HTTP动词来操作资源

常用HTTP动词

• RESTful解释
  • GET/POST/PUT/DELETE分别用来 获取/新建/更新/删除 资源
  • 幂等性：GET/PUT/DELETE是幂等操作（无论操作多少次都是获得同样的数据，幂等的可以放心的多次请求，非幂等就要注意）
  • 幂等指的是无论一次还是多次操作具有一样的副作用

Tornado RESTful Api示例

HTTP方法	URL	动作
GET	http://[hostname]/api/users	检索用户列表
GET	http://[hostname]/api/users/[user_id]	检索单个用户
POST	http://[hostname]/api/users	创建新用户
PUT	http://[hostname]/api/users/[user_id]	更新用户信息
DELETE	http://[hostname]/api/users/[user_id]	删除用户

简单实现

• 使用Tornado实现Restful Api
  • Tornado适合构建RESTful微服务
  • 实现UserModel
  • 实现UserListRequesthandler和UserRequestHandler

相关代码

# models/user.py
class UserModel(object):
	users = {
		1: {'name': 'zhang', 'age': 10},
		2: {'name': 'wang', 'age': 12},
		3: {'name': 'li', 'age': 14},
		4: {'name': 'zhao', 'age': 11},
	}

	@classmethod
	def get(cls, user_id):
		return cls.users[user_id]

	@classmethod
	def get_all(cls):
		return list(cls.users.values())

	@classmethod
	def create(cls, name ,age):
		user_dict = {'name': name, 'age': age}
		max_id = max(cls.users.keys()) + 1
		cls.users[max_id] = user_dict

	@classmethod
	def update(cls, user_id, age):
		cls.users[user_id]['age'] = age

	@classmethod
	def delete(cls, user_id):
		if user_id in cls.users:
			return cls.users.pop(user_id)

# handlers/user.py
import tornado.web
from tornado.escape import json_encode
from models.user import UserModel

class UserListHandler(tornado.web.RequestHandler):
	def get(self):
		users = UserModel.get_all()
		self.write(json_encode(users))

	def post(self):
		name = self.get_argument('name')
		age = self.get_argument('age')
		UserModel.create(name, age)
		resp = {'status': True, 'msg': 'create success'}
		self.write(json_encode(resp))

class UserHandler(tornado.web.RequestHandler):
	def get(self, user_id):
		try:
			user = UserModel.get(int(user_id))
		except KeyError:
			return self.set_status(404)
		self.write(json_encode(user))

	def put(self, user_id):
		age = self.get_argument('age')
		UserModel.update(int(user_id), age)
		resp = {'status': True, 'msg': 'update success'}
		self.write(json_encode(resp))

	def delete(self, user_id):
		UserModel.delete(int(user_id))
		resp = {'status': True, 'msg': 'delete success'}
		self.write(json_encode(resp))

# app.py
import tornado.web
from handlers import user as user_handlers

HANDLERS = [
	(r"/api/users", user_handlers.UserListHandler),
	(r"/api/users/(\d+)", user_handlers.UserHandler)
]

def run():
	app = tornado.web.Application(
		HANDLERS,
		debug=True,
	)
	http_server = tornado.httpserver.HTTPServer(app)
	port = 8888
	http_server.listen(port)
	print('Server start on port {}'.format(port))
	tornado.ioloop.IOLoop.instance().start()

if __name__ == '__main__':
    run()