Servlet程序创建的两种方式

方式一：实现Servlet接口

步骤：
* 1.声明一个Servlet类，实现Servlet接口
* 2.实现service方法，处理请求，并响应数据
* 3.到web.xml中去配置Servlet程序的访问地址

方式二：继承HttpServlet类

步骤：
* 1.声明一个Servlet类，继承于HttpServlet类
* 2.重写doGet()方法或者doPost()方法
* 3.到web.xml中去配置Servlet程序的访问地址


相关代码

package com.orzjiangxiaoyu.servlet;

import jakarta.servlet.*;
import jakarta.servlet.http.HttpServlet;

import java.io.IOException;

/**
 * Servlet程序实现方式一：实现Servlet接口
 *步骤：
 * 1.声明一个Servlet类，实现Servlet接口
 * 2.实现service方法，处理请求，并响应数据
 * 3.到web.xml中去配置Servlet程序的访问地址
 * @author orz
 * @create 2020-09-09 23:23
 */

//1.声明一个Servlet类，继承于Servlet接口

public class Servlet1 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 {

//        2.实现service方法，处理请求，并响应数据
        System.out.println("实现service方法，处理请求");
    }

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

    @Override
    public void destroy() {

    }
}

package com.orzjiangxiaoyu.servlet;

import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;

/**
 * Servlet程序实现方式二：继承HttpServlet类
 * 步骤：
 * 1.声明一个Servlet类，继承于HttpServlet类
 * 2.重写doGet()方法或者doPost()方法
 * 3.到web.xml中去配置Servlet程序的访问地址
 * @author orz
 * @create 2020-09-09 23:33
 */

//1.声明一个Servlet类，继承于HttpServlet类

public class Servlet2 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

//        2.重写doGet()方法或者doPost()方法
        System.out.println("Servlet2 doGet");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("Servlet2 doPost");
    }
}

package com.orzjiangxiaoyu.servlet;

import jakarta.servlet.*;
import jakarta.servlet.http.HttpServletRequest;

import java.io.IOException;

/**Servlet程序实现方式一：实现Servlet接口,加上doGet请求或doPost请求
 * @author orz
 * @create 2020-09-09 23:39
 */

//1.声明一个Servlet类，继承于Servlet接口

public class Servlet3 implements Servlet {
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {

    }

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

    public void doGet()
    {
        System.out.println("Servlet3 doGet");
    }
    public void doPost()
    {
        System.out.println("Servlet3 doPost");
    }
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {

        //2.实现service方法，处理请求，并响应数据
        HttpServletRequest servletRequest1 = (HttpServletRequest) servletRequest;
        String method = servletRequest1.getMethod();
        if("GET".equals(method))
        {
            doGet();
        }
        else if("POST".equals(method))
        {
            doPost();
        }
    }

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

    @Override
    public void destroy() {

    }
}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
<!--  Servlet程序实现方式一：实现Servlet接口   -->
    <!--    到web.xml中去配置Servlet程序的访问地址-->
    <servlet>
        <servlet-name>Servlet1</servlet-name>
        <servlet-class>com.orzjiangxiaoyu.servlet.Servlet1</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Servlet1</servlet-name>
        <url-pattern>/servlet1</url-pattern>
    </servlet-mapping>

<!--    -->

<!--    Servlet程序实现方式二：继承HttpServlet类-->
    <servlet>
        <servlet-name>Servlet2</servlet-name>
        <servlet-class>com.orzjiangxiaoyu.servlet.Servlet2</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Servlet2</servlet-name>
        <url-pattern>/servlet2</url-pattern>
    </servlet-mapping>
<!--    -->

<!--    Servlet程序实现方式一：实现Servlet接口,加上doGet请求或doPost请求-->
    <servlet>
        <servlet-name>Servlet3</servlet-name>
        <servlet-class>com.orzjiangxiaoyu.servlet.Servlet3</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Servlet3</servlet-name>
        <url-pattern>/servlet3</url-pattern>
    </servlet-mapping>
</web-app>