[Java知识库]Javaweb - Servlet体系结构、HttpServlet实现类

Servlet体系结构

我们将来开发B/S架构的web项目，都是针对HTTP协议，所以我们自定义Servlet，会继承HttpServlet

案例演示1

新建ServletDemo04

package com.taotao.web;

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 ServletDemo04 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...");
    }
}

run maven运行测试

打开项目访问路径

输入demo4

演示service方法处理get和post

新建ServletDemo05

package com.taotao.web;

import javax.servlet.*;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

public class ServletDemo05 implements Servlet {

    @Override
    public void init(ServletConfig servletConfig) throws ServletException {

    }

    @Override
    public ServletConfig getServletConfig() {
        return null;
    }

    @Override
    @SuppressWarnings({"all"})
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        //根据请求方式不同，进行分别处理

        //向下转型，得到request对象
        HttpServletRequest request = (HttpServletRequest) servletRequest;

        //1.获取请求方式
        String method = request.getMethod();

        //2.判断
        if("GET".equals(method)){
            //get方式的处理逻辑
        }else{
            //post方式的处理逻辑
        }
    }

    @Override
    public String getServletInfo() {
        return null;
    }

    @Override
    public void destroy() {

    }
}

新建工具类

新建MyHttpServlet

package com.taotao.web;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

public class MyHttpServlet implements Servlet {

    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
        
    }

    @Override
    public ServletConfig getServletConfig() {
        return null;
    }

    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        //根据请求方式不同，进行分别处理

        //向下转型，得到request对象
        HttpServletRequest request = (HttpServletRequest) servletRequest;

        //1.获取请求方式
        String method = request.getMethod();

        //2.判断
        if("GET".equals(method)){
            //get方式的处理逻辑
            doGet(servletRequest,servletResponse);
        }else{
            //post方式的处理逻辑
            doPost(servletRequest,servletResponse);
        }
    }

    protected void doPost(ServletRequest servletRequest, ServletResponse servletResponse) {
    }

    protected void doGet(ServletRequest servletRequest, ServletResponse servletResponse) {
        
    }


    @Override
    public String getServletInfo() {
        return null;
    }

    @Override
    public void destroy() {

    }
}

新建测试类，继承工具类

ServletDomo05

package com.taotao.web;

import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebServlet;

@WebServlet("/demo5")       //配置访问路径demo5
public class ServletDemo05 extends MyHttpServlet{
    @Override
    protected void doGet(ServletRequest servletRequest, ServletResponse servletResponse) {
        System.out.println("get...");
    }

    @Override
    protected void doPost(ServletRequest servletRequest, ServletResponse servletResponse) {
        System.out.println("post...");
    }
}

测试运行

总结