创建servlet的三种方式

第一种方式，实现Servlet接口

 package com.example.servlet;

 import java.io.IOException;

 import javax.servlet.Servlet;

 import javax.servlet.ServletConfig;

 import javax.servlet.ServletException;

 import javax.servlet.ServletRequest;

 import javax.servlet.ServletResponse;

 public class testServlet1 implements Servlet {

     /**

      * 销毁方法

      */

     public void destroy() {

         System.out.println("这是销毁方法！");

     }

     /**

      * 初始化方法

      */

     public void init(ServletConfig arg0) throws ServletException {

         System.out.println("这是初始化方法！");

     }

     /**

      * 服务方法

      */

     public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {

         System.out.println("这是服务方法！");

     }

     //获取servlet配置信息

     public ServletConfig getServletConfig() {

         return null;

     }

     //获取servlet信息

     public String getServletInfo() {

         return null;

     }

 }

第二种方式：继承GenericServlet抽象类

GenericServlet抽象类中只有一个抽象方法service()方法

 package com.example.servlet;

 import java.io.IOException;

 import javax.servlet.GenericServlet;

 import javax.servlet.ServletException;

 import javax.servlet.ServletRequest;

 import javax.servlet.ServletResponse;

 public class testServlet2 extends GenericServlet{

     @Override

     public void service(ServletRequest arg0, ServletResponse arg1) throws ServletException, IOException {

         System.out.println("这是服务方法！");

     }

 }

第三种方式：继承HttpServlet抽象类重写doGet()和doPost()方法

 package com.example.servlet;

 import javax.servlet.ServletException;

 import javax.servlet.http.HttpServlet;

 import javax.servlet.http.HttpServletRequest;

 import javax.servlet.http.HttpServletResponse;

 import java.io.IOException;

 public class testServlet3 extends HttpServlet{

     @Override

     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

         System.out.println("这是get方法提交");

     }

     @Override

     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

         System.out.println("这是post方法提交");

     }

 }

web.xml配置文件如下

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

         xmlns="http://xmlns.jcp.org/xml/ns/javaee"

         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"

         version="3.1">

    <!-- sevlet配置 -->

    <!-- 1.servlet的定义：告诉容器如何来创建servlet -->

    <servlet>

        <servlet-name>test1</servlet-name>

        <servlet-class>com.example.servlet.testServlet1</servlet-class>

    </servlet>

    <!-- 2.配置servlet路径 servlet映射 -->

    <!-- url-pattern 必须以/开头 访问：http://localhost:8080/servletPro/login  -->

    <servlet-mapping>

        <servlet-name>test1</servlet-name>

        <url-pattern>/login1</url-pattern>

    </servlet-mapping>

    <servlet>

        <servlet-name>test2</servlet-name>

        <servlet-class>com.example.servlet.testServlet1</servlet-class>

    </servlet>

    <servlet-mapping>

        <servlet-name>test2</servlet-name>

        <url-pattern>/login2</url-pattern>

    </servlet-mapping>

    <servlet>

        <servlet-name>test3</servlet-name>

        <servlet-class>com.example.servlet.testServlet1</servlet-class>

    </servlet>

    <servlet-mapping>

        <servlet-name>test3</servlet-name>

        <url-pattern>/login3</url-pattern>

    </servlet-mapping>

</web-app>