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>