Talking about Servlet

What is? Servlet？

Simply speaking Servlet yes java Write a server-side program , Running on the web Server , It is a component of dynamic web pages spliced by different users .

Servlet What's the role ？

1. Receive the request from the client
2. Call other java Program to process requests
3. Will deal with the result , Return to the server

Servlet How to create ？

1、 Create class inheritance HttpServlet
2、 Override unimplemented methods –service Method

Servlet Life cycle of （ a key ）

We study Servlet The life cycle of mainly studies the following points ：

Construction method ：

• establish servlet Object . By default , First visit to this servlet Call the constructor to create an object . The constructor is called only once ,servlet The object is tomcat Is a singleton .

init(); Method ：

• Created servlet Object . Just call 1 Time .

service();：

• Call this method every time the browser makes a request . Callable n Time .

destory();

• The destruction servlet Object . for example ： Stop the server or redeploy web Destroy when applying servlet object . Call it once .