Servlet体系结构和Servlet_urlpartten配置

Servlet：

• 概念

• 步骤

• 执行原理

• 生命周期

• Servlet3.0 注解配置

• Servlet的体系结构

  • Servlet -- 接口
    |
  • GenericServlet -- 抽象类
    |
  • HttpServlet -- 抽象类

• GenericServlet：将Servlet接口中其他的方法做了默认空实现，只将service()方法作为抽象

  • 将来定义Servlet类时，可以继承GenericServlet，实现service()方法即可

package com.ailyt.servlet;

import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebServlet;
import java.io.IOException;
@WebServlet(value = "/demo2")
public class ServletStudy4 extends GenericServlet {
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("demo2....");
    }
}

• HttpServlet：对http协议的一种封装，简化操作

  • 定义类继承HttpServlet
  • 复写doGet/doPost方法

• Servlet相关配置

  • urlpartten：Servlet访问路径
    • 一个Servlet可以定义多个访问路径：@WebServlet({"/d4","/dd4","/ddd4"})
    • 路径定义规则：
      • /xxx
      • /xxx/xxx：多层路径，目录结构
      • *.do

package com.ailyt.servlet;


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;

/**
 * Servlet路径配置
 */
//@WebServlet({"/d4","/dd4","/ddd4"})
//@WebServlet("/user/demo4")
//@WebServlet("/user/*")
//@WebServlet("/*")
//@WebServlet("*.do")
public class ServletStudy6 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("doGet");
    }
}