Web Server(Simple workflow):
1、Create httpListener
2、Receive Socket Data
3、Parse data
4、Create new thread for this request
5、Create Context (Request Response)
6、Through filter or moudle to modify Context
7、Find servlet or handler to resolve
8、Response to Client
大概的等价关系：
| 功能 | J2SE（Tomcat） | .Net（IIS） |
| 过滤器 | Filter | Moudle |
| 处理器 | Servlet | Handler |
| 监听器 | Listener | Event |
