創建servlet的三種方式

第一種方式，實現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 {

    /**
     * 銷毀方法
     */
    public void destroy() {
        System.out.println("這是銷毀方法！");
        
    }
    
    /**
     * 初始化方法
     */
    public void init(ServletConfig arg0) throws ServletException {
        System.out.println("這是初始化方法！");
    }

    /**
     * 服務方法
     */
    public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
        
        System.out.println("這是服務方法！");
        
    }

    
    //獲取servlet配置信息
    public ServletConfig getServletConfig() {
        
        return null;
    }

    //獲取servlet信息
    public String getServletInfo() {
        
        return null;
    }
}

第二種方式：繼承GenericServlet抽象類

GenericServlet抽象類中只有一個抽象方法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("這是服務方法！");
    }

}

第三種方式：繼承HttpServlet抽象類重寫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("這是get方法提交");
        
    }
    

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("這是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的定義：告訴容器如何來創建servlet -->
    <servlet>
        <servlet-name>test1</servlet-name>
        <servlet-class>com.example.servlet.testServlet1</servlet-class>
    </servlet>

    <!-- 2.配置servlet路徑 servlet映射 -->
    <!-- url-pattern 必須以/開頭 訪問：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>