深入理解JavaWeb中过滤器与监听器的应用

<filter>
    <filter-name>myfilter</filter-name>
    <filter-class>com.yuan.filter.MyFilter</filter-class>
 </filter>
 <filter-mapping>
    <filter-name>myfilter</filter-name>
    <url-pattern>*.do</url-pattern>
 </filter-mapping>

package com.yuan.filter;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
@WebFilter
public class MyFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        // 初始化方法
    }
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        // 对请求进行加工
        filterChain.doFilter(servletRequest, servletResponse);
    }
    @Override
    public void destroy() {
        // 销毁方法
    }
}

  <listener>
    <listener-class>com.yuan.listener.MyListener</listener-class>
  </listener>

package com.yuan.listener;
import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;
public class MyListener implements HttpSessionAttributeListener {
    @Override
    public void attributeAdded(HttpSessionBindingEvent se) {
        // 向session加入信息时执行的方法
    }
    @Override
    public void attributeRemoved(HttpSessionBindingEvent se) {
        // 从session中移除信息时执行的方法
    }
    @Override
    public void attributeReplaced(HttpSessionBindingEvent se) {
        // session中的信息被替换时执行的方法
    }
}