Servlet lifecycle

package com.htf.web.controller;

import java.io.IOException;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * servlet Life cycle of 
 * 1. Load one servlet class 
 * 2. Instantiation 
 * 3. initialization 
 * 4. There's a request to come , that   call service Method treatment   (service Method regardless of the request method , He can handle it )
 * 5.service Method according to the request get still post, call doGet（ Can only handle get Method request ） perhaps doPost（ Can only handle post Method request ） Handle 
 * 6. The destruction servlet
 * 
 *  Under normal circumstances, the life cycle is like this 
 *  Construction method ---->init(ServletConfig config)---->service()---->doGet()
 * 1. Only request servlet,servlet Will be instantiated 
 * 2. Instantiation methods and initialization methods are executed only once in the life cycle 
 * 3.tomcat When you restart, it will , The destruction servlet
 * 
 *  A special case 1
 *  If servlet A special , Need to be in other servlet Initialization before （tomcat Instantiate at startup servlet）, So you can configure loadOnStartup=0
 *  As we learn later springMVC At the time of the DispatcherServlet, That's what he is servlet
 * 
 *  A special case 2
 *  You need to get it and pass it to servlet When initializing parameters for 
  Definition servlet Is the initialization parameter of 
 * <servlet>
  	<servlet-name>Servlet2</servlet-name>
  	<servlet-class>com.neuedu.web.controller.Servlet2</servlet-class>
  	<init-param>
  		<param-name>ENCODE</param-name>
  		<param-value>utf-8</param-value>
  	</init-param>
  *</servlet> 
  
  *  @Override
	public void init(ServletConfig config) throws ServletException {
		// How to get and pass to servlet The initialization parameters of ？
		String value=config.getInitParameter("ENCODE");
		System.out.println("encode:"+value);
	}
 *
 * @author htf
 *
 */

@WebServlet(value="/Servletlife",loadOnStartup=0)
public class Servletlife extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public Servletlife() {
		System.out.println(" Instantiation Servletlife");
	}

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		System.out.println("=====doGet()=====");
	}

	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		System.out.println("=====doPost()=====");
	}

	@Override
	protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("=====service()=====");
		//service Method depends on the requested method or get still post, call doGet perhaps doPost
		String mothod=request.getMethod();
		if("GET".equalsIgnoreCase(mothod)) {
			doGet(request, response);
		}
		if("POST".equalsIgnoreCase(mothod)) {
			doPost(request, response);
		}
	}

	@Override
	public void destroy() {
		System.out.println("=====destroy()=====");
	}

	@Override
	public void init() throws ServletException {
		System.out.println("=====init()=====");
	}

	@Override
	public void init(ServletConfig config) throws ServletException {
		System.out.println("=====init(ServletConfig config)=====");
	}
       
}