//Servlet的生命周期:从Servlet被创建到Servlet被销毁的过程
//一次创建，到处服务
//一个Servlet只会有一个对象，服务所有的请求
/* * 1.实例化（使用构造方法创建对象）
* 2.初始化 执行init方法
* 3.服务 执行service方法
* 4.销毁 执行destroy方法
*/
public class ServletDemo1 implements Servlet { //public ServletDemo1(){}
//生命周期方法:当Servlet第一次被创建对象时执行该方法,该方法在整个生命周期中只执行一次
public void init(ServletConfig arg0) throws ServletException { System.out.println("=======init========="); }
//生命周期方法:对客户端响应的方法,该方法会被执行多次，每次请求该servlet都会执行该方法 public void service(ServletRequest arg0, ServletResponse arg1) throws ServletException, IOException { System.out.println("hehe"); }
//生命周期方法:当Servlet被销毁时执行该方法 public void destroy() { System.out.println("******destroy**********"); }
//当停止tomcat时也就销毁的servlet。 public ServletConfig getServletConfig()
{ return null; } public String getServletInfo() { return null; } }
The second way to create a servlet is to inherit from the GenericServlet class, which implements the Servlet interface in addition to the service methods.
However, we rarely use this method
public class ServletDemo2 extends GenericServlet { @Override public void service(ServletRequest arg0, ServletResponse arg1) throws ServletException, IOException {
System.out.println("heihei");
}
}
The third way to create a servlet, and the one we often use,
inherits HttpServlet method
public class ServletDemo3 extends HttpServlet {
@Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("haha");
}
@Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("ee");
doGet(req,resp);
}
}