/*

原先servlet
在web.xml 文件中需要配置大量的信息：

<servlet>

<servlet-name>AServlet</servlet-name>

<servlet-class>cn.itcast.web.servlet.AServlet</servlet-class>

<init-param>

<param-name>p1</param-name>

<param-value>v1</param-value>

</init-param>

<init-param>

<param-name>p2</param-name>

<param-value>v2</param-value>

</init-param>

<load-on-startup>1<load-on-startup>

</servlet>

<servlet-mapping>

<servlet-name>AServlet</servlet-name>

<url-pattern>/AServlet</url-pattern>

<url-pattern>/AAServlet</url-pattern>

</servlet-mapping>

*/

/*

* 但是现在使用
注解，就方便多了

*/

@WebServlet(urlPatterns="/AServlet",

    initParams={

        @WebInitParam(name="p1", value="v1"),

        @WebInitParam(name="p2", value="v2")

    },

    loadOnStartup=1

)

public
class
AServlet
extends HttpServlet {

    public
void doGet(HttpServletRequest req, HttpServletResponse resp)

            throws ServletException, IOException {

        System.out.println("hello servlet3.0!");

        resp.getWriter().print("hello servlet3.0!!");

    }

}

//(urlPatterns="/*") 表示
：
过滤所有的路径

@WebFilter(urlPatterns="/*")

public
class AFilter implements Filter {

    @Override

    public
void destroy() {

        // TODO Auto-generated method stub

    }

    @Override

    public
void doFilter(ServletRequest request, ServletResponse repsonse,

            FilterChain chain) throws IOException, ServletException {

        System.out.println("哈哈~，你看到我没有！");

        chain.doFilter(request, repsonse);//放行

    }

    @Override

    public
void init(FilterConfig arg0) throws ServletException {

        // TODO Auto-generated method stub

    }

}

import javax.servlet.ServletContextEvent;

import javax.servlet.ServletContextListener;

import javax.servlet.annotation.WebListener;

//监听器的注解

@WebListener

public
class AListener implements ServletContextListener {

    @Override

    public
void contextDestroyed(ServletContextEvent arg0) {

        System.out.println("死掉了");

    }

    @Override

    public
void contextInitialized(ServletContextEvent arg0) {

        System.out.println("出生了");

    }

}