Servlet创建的三种方式

目录

• 1 实现Servlet接口
• 2 继承GenericServlet
• 3 继承HttpServlet
• 4 web.xml配置

关于servlet的创建，我们有三种方式。

• 实现Servlet接口

• 继承GenericServlet

• 继承HttpServlet

1 实现Servlet接口

实现五个抽象方法

package com.zjw;

import javax.servlet.*;
import java.io.IOException;

public class MyServlet implements Servlet {

    public MyServlet() {
        System.out.println("MyServlet构造方法....");
    }

    @Override
    public void init(ServletConfig config) throws ServletException {
        System.out.println("init....");
    }

    @Override
    public ServletConfig getServletConfig() {
        System.out.println("getServletConfig....");
        return null;
    }

    @Override
    public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
        System.out.println("service....");
    }

    @Override
    public String getServletInfo() {
        System.out.println("getServletInfo....");
        return null;
    }

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

2 继承GenericServlet

实现service抽象方法

package com.zjw;

import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import java.io.IOException;

public class GenServlet extends GenericServlet {
    @Override
    public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
        System.out.println("哈哈哈");
    }
}

3 继承HttpServlet

需要重写doGet、doPost方法，否则请求不被允许。

package com.zjw;

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 HttpsServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("这个是get请求");
    }

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

4 web.xml配置

<?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>
        <servlet-name>my</servlet-name>
        <servlet-class>com.zjw.MyServlet</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>gs</servlet-name>
        <servlet-class>com.zjw.GenServlet</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>hs</servlet-name>
        <servlet-class>com.zjw.HttpsServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>my</servlet-name>
        <url-pattern>/myservlet</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>gs</servlet-name>
        <url-pattern>/gs</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>hs</servlet-name>
        <url-pattern>/hs</url-pattern>
    </servlet-mapping>
</web-app>