Tornadao—接口与调用顺序

目录

1. initialize()
2. prepare()
3. HTTP方法
4. 调用顺序

---

• initialize()

  ---

  对应每个请求的处理类Handler在构造⼀个实例后⾸先执⾏initialize()⽅法。将路由
  映射中的第三个字典型参数会作为该⽅法的命名参数传递，如：
  
  class ProfileHandler(RequestHandler):
   def initialize(self, database):
   self.database = database
   def get(self):
   ...
  app = Application([
   (r'/user/(.*)', ProfileHandler, dict(database=database)),
   ])
  
  此⽅法通常⽤来初始化参数（对象属性），

• prepare()

  ---

  import json
  class IndexHandler(RequestHandler):
   def prepare(self):
   if self.request.headers.get("ContentType").startswith("application/json"):
   self.json_dict = json.loads(self.request.body)
   else:
   self.json_dict = None
   def post(self):
   if self.json_dict:
   for key, value in self.json_dict.items():
   self.write("<h3>%s</h3><p>%s</p>" % (key, value))
   def put(self):
   if self.json_dict:
   for key, value in self.json_dict.items():
   self.write("<h3>%s</h3><p>%s</p>" % (key, value))

• HTTP方法

  ---

  

• 调用顺序

  ---

  class IndexHandler(RequestHandler):
   def initialize(self):
   print "调⽤了initialize()"
   def prepare(self):
   print "调⽤了prepare()"
   def set_default_headers(self):
   print "调⽤了set_default_headers()"
   def write_error(self, status_code, **kwargs):
   print "调⽤了write_error()"
   def get(self):
   print "调⽤了get()"
   def post(self):
   print "调⽤了post()"
   self.send_error(200) # 注意此出抛出了错误
   def on_finish(self):
   print "调⽤了on_finish()"
  
  在正常情况未抛出错误时，调⽤顺序为：
  1. set_defautl_headers()
  2. initialize()
  3. prepare()
  4. HTTP⽅法
  5. on_finish()
  在有错误抛出时，调⽤顺序为：
  1. set_default_headers()
  2. initialize()
  3. prepare()
  4. HTTP⽅法
  5. set_default_headers()
  6. write_error()
  7. on_finish()