JavaWeb之Filter与Listener使用解析

package com.learn.web.filter;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
/**
 * @author 咕咕猫
 * @version 1.0
 */
@WebFilter("/*")
public class FilterDemo implements Filter {
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        //放行前，对request数据进行处理
        System.out.println("1. FilterDemo....");
        //放行
        filterChain.doFilter(servletRequest,servletResponse);
        //放行后，对response数据进行处理
        System.out.println("3. FilterDemo....");
    }
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }
    @Override
    public void destroy() {
    }
}

package com.learn.web.listener;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
/**
 * @author 咕咕猫
 * @version 1.0
 */
@WebListener
public class ContextLoaderListener implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent servletContextEvent) {
        //加载资源
        System.out.println("ContextLoaderListener...");
    }
    @Override
    public void contextDestroyed(ServletContextEvent servletContextEvent) {
        //释放资源
    }
}