JavaWeb知识核心--Servlet体系结构

Servlet –接口

  Servlet          --接口
GenericServlet    --抽象类
HttpServlet       --抽象类

GenericServlet

里面只有一个service方法作为抽象，因为里面其他方法已经默认做了空实现
其他方法可选择性实现

package com.web.servlet;

import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import java.io.IOException;

public class ServletDemo2 extends GenericServlet {
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {

    }
}

HttpServlet

因为要判断get和post方式，很麻烦，因此sun公司帮我们实现了这个判断-HttpServlet
HttpServlet：对http协议的封装，简化操作

步骤

1. 定义类继承HttpServlet
2. 复写doGet() / doPost()方法

package com.web.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;
@WebServlet(urlPatterns = "/s3")
public class ServletDemo3 extends HttpServlet {
    @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...");
    }
}

Servlet相关配置

urlpartten

1. Servlet访问路径
   注解里面可以定义多个路径
   @WebServlet(urlPatterns = {“/s3”,”/s31”,”/s32”})

2. 路径定义规则

   1.   /xxx
   2.   /xxx/xxx   :多层路径，目录结构
           @WebServlet(urlPatterns = "/user/s1")
           @WebServlet(urlPatterns = "/user/*")
           @WebServlet(urlPatterns = "/*")
           //*代表任意路径，通配符
   3.   *.do
           @WebServlet(urlPatterns = "*.do")
           // 路劲前面不能加/，否则报错，访问为xxx.do
           //后缀名可以为任意的