java注解的形式配置servlet、filter、listener

        刚入职时因为项目已经做了一部分 然后大佬跑路了  只能自己接着做   发现没有用框架      现在项目尾声了  觉得配置xml文件太麻烦  选择注解的形式  。

---

Servlet配置方式：

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *   name servlet的名字 等同  <servlet-name>A</servlet-name>
 *   urlPatterns    等同  <url-pattern>/A</url-pattern>
 */

@WebServlet(name="A",urlPatterns="/A")
public class A extends HttpServlet{

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

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

 filter 配置方式

import java.io.IOException;

import javax.servlet.annotation.WebFilter;

import com.sun.net.httpserver.Filter;
import com.sun.net.httpserver.HttpExchange;

/**
 *   filterName filter的名字 等同  <filter-name>A</filter-name>  可以省略
 *   urlPatterns    等同  <url-pattern>*</url-pattern>
 */

@WebFilter(filterName="A",urlPatterns="*")
public class A extends Filter{

	@Override
	public String description() {
		return null;
	}

	@Override
	public void doFilter(HttpExchange arg0, Chain arg1) throws IOException {
		
	}

	
}

Listener 配置方式

 
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
 
/**
 * 使用@WebListener注解将实现了ServletContextListener接口的MyServletContextListener标注为监听器
 */
@WebListener
public class A implements ServletContextListener {
 
    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        System.out.println("ServletContex销毁");
    }
 
    @Override
    public void contextInitialized(ServletContextEvent sce) {
        System.out.println("ServletContex初始化");
    }
}