Servlet 应用是如何工作的

原文：https://www.studytonight.com/servlet/how-a-servlet-application-work.php

Web 容器负责管理 Java EE 应用的 servlets 和 JSP 页面的执行。

当一个请求进入一个 servlet 时，服务器将请求传递给网络容器。 Web 容器负责实例化 servlet 或者创建一个新的线程来处理请求。Web 容器的工作是获取对 servlet 的请求和响应。容器创建多个线程来处理对单个 servlet 的多个请求。

servlet 没有 main()方法。Web 容器管理一个 Servlet 实例的生命周期。

关于 Servlet 如何工作的快速修订

1. User sends request for a servlet by clicking a link that has URL to a servlet.

   

2. The container finds the servlet using deployment descriptor and creates two objects :

   1. 【http servletrequest】
   2. 【http servletresponse】

   

3. Then the container creates or allocates a thread for that request and calls the Servlet's service() method and passes the request, response objects as arguments.

   

4. The service() method, then decides which servlet method, doGet() or doPost() to call, based on HTTP Request Method(Get, Post etc) sent by the client. Suppose the client sent an HTTP GET request, so the service() will call Servlet's doGet() method.

   

5. Then the Servlet uses response object to write the response back to the client.

   

6. After the service() method is completed the thread dies. And the request and response objects are ready for garbage collection.