新建一个javaweb项目，然后添加依赖

<!--servlet-->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.0.1</version>
        </dependency>

package com.bruce;

import javax.servlet.ServletConfig;
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;
import java.io.PrintWriter;

@WebServlet(description = "Servlet示例", name = "hello", urlPatterns = {"/MyFirst"}, loadOnStartup = 1)
public class ServletDemo extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.getWriter().append("my frist servlet");
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
        System.out.println("do post");
    }

    @Override
    public void init(ServletConfig config) throws ServletException {
        System.out.println("Servlet初期化" + config.getServletName());
    }

    @Override
    public ServletConfig getServletConfig() {
        return super.getServletConfig();
    }

    @Override
    public String getServletInfo() {
        return super.getServletInfo();
    }

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("Servlet处理请求");
        response.setCharacterEncoding("UTF-8");
        //告诉浏览器输出的内容是html,并且以utf-8的编码来查看这个内容。
        response.setContentType("text/html;charset=utf-8");
        PrintWriter printWriter = response.getWriter();
        printWriter.println("你好，这是来自Servlet的消息：Hello World!");
    }

    @Override
    public void destroy() {
        System.out.println("Servlet销毁");
    }
}

在servlet3.0+可以不用在web.xml配置servlet,可以直接使用注解@WebServlet

<!DOCTYPE web-app PUBLIC
        "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
        "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
    <display-name>Archetype Created Web Application</display-name>
    <!--<servlet>-->
        <!--<servlet-name>MyFirstServlet</servlet-name>-->
        <!--<servlet-class>com.bruce.ServletDemo</servlet-class>-->
    <!--</servlet>-->
    <!--<servlet-mapping>-->
        <!--<servlet-name>MyFirstServlet</servlet-name>-->
        <!--<url-pattern>/MyFirst</url-pattern>-->
    <!--</servlet-mapping>-->
</web-app>