Servlet方法介绍及体系结构

void  init(ServletConfig  config)

void  service(ServletRequest  req,ServletResponse  res)

void  detroy()

ServletConfig getServletConfig()

String  getServletInfo()

import javax.servlet.*;
import javax.servlet.annotation.WebServlet;
import java.io.IOException;
/**
 * Servlet：生命周期方法
 */
@WebServlet(urlPatterns = "/demo3",loadOnStartup = 1)
public class ServletDemo3 implements Servlet {
    private ServletConfig config;
    /**
     * 初始化方法
     * 1、调用时间：Servlet被第一次访问时，调用
     * 2、调用次数：1次
     * @param servletConfig
     * @throws ServletException
     */
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
        this.config = config;
        System.out.println("init...");
    }
    @Override
    public ServletConfig getServletConfig() {
        return config;
    }
    /**
     * 提供服务
     * 1、调用时间，每一次Servlet被访问时，调用
     * 2、调用次数：多次
     *
     * @param servletRequest
     * @param servletResponse
     * @throws ServletException
     * @throws IOException
     */
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("servlet hello world~");
    }
    /**
     * 销毁方法
     * 1、调用时间，内存释放或者服务器关闭的时候，Servlet对象会被销毁，调用
     * 2、调用次数：1次
     */
    @Override
    public void destroy() {
        System.out.println("destroy...");
    }
    @Override
    public String getServletInfo() {
        return "";
    }
}

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet("/demo4")
public class ServletDemo4 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("get...");
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("post...");
    }
}