适配器模式改造Servlet
一、引入适配器
二、适配器设计模式Adapter
2.1 实例
2.2 方法
package servlet;
import jakarta.servlet.*;
import java.io.IOException;
/**
* @Author: 小雷学长
* @Date: 2022/3/17 - 19:47
* @Version: 1.8
*/
/**
* 编写一个标准通用的Servlet,起名:GenericServlet
* 以后所有的Servlet类都不要直接实现Servlet接口了
* 以后所有的Servlet类都要继承GenericServlet类
* GenericServlet 就是一个适配器
*/
public abstract class GenericServlet implements Servlet {
@Override
public void init(ServletConfig servletConfig) throws ServletException {
}
@Override
public ServletConfig getServletConfig() {
return null;
}
/**
* 抽象方法,这个最常用,所以要求子类必须实现service方法
* @param servletRequest
* @param servletResponse
* @throws ServletException
* @throws IOException
*/
@Override
public abstract void service(ServletRequest servletRequest, ServletResponse servletResponse)
throws ServletException, IOException;
@Override
public String getServletInfo() {
return null;
}
@Override
public void destroy() {
}
}
package servlet;
import jakarta.servlet.ServletException;
import jakarta.servlet.ServletRequest;
import jakarta.servlet.ServletResponse;
import java.io.IOException;
/**
* @Author: 小雷学长
* @Date: 2022/3/17 - 21:03
* @Version: 1.8
*/
public class VipServlet extends GenericServlet {
@Override
public void service(ServletRequest servletRequest, ServletResponse servletResponse)
throws ServletException, IOException {
System.out.println("VIP");
}
}
package servlet;
import jakarta.servlet.ServletException;
import jakarta.servlet.ServletRequest;
import jakarta.servlet.ServletResponse;
import java.io.IOException;
public class LoginServlet extends GenericServlet{
@Override
public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
System.out.println("Login");
}
}
<?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>loginServlet</servlet-name>
<servlet-class>servlet.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>loginServlet</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>VIPServlet</servlet-name>
<servlet-class>servlet.VipServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>VIPServlet</servlet-name>
<url-pattern>/VIP</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>aservlet</servlet-name>
<servlet-class>servlet.AServlet</servlet-class>
<!--<load-on-startup>0</load-on-startup>-->
</servlet>
<servlet-mapping>
<servlet-name>aservlet</servlet-name>
<url-pattern>/a</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>bservlet</servlet-name>
<servlet-class>servlet.BServlet</servlet-class>
<!--<load-on-startup>1</load-on-startup>-->
</servlet>
<servlet-mapping>
<servlet-name>bservlet</servlet-name>
<url-pattern>/b</url-pattern>
</servlet-mapping>
</web-app>
三、改造GenericServlet
3.1 关于init方法