ServletRequestListener | 監聽器 | 應用例子

ServletRequestListener 監聽器

package cn.qiu;

import javax.servlet.ServletRequest;
import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;
import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpServletRequest;

/**
 * ServletRequestListener 監聽器
 * 應用【計算一次HTTP請求的時間】
 * @author QiuRiMangCao
 */
@WebListener
public class RerfStartListener implements ServletRequestListener{

    @Override
    public void requestDestroyed(ServletRequestEvent arg0) {
        ServletRequest servletRequest = arg0.getServletRequest();
        long start = (long) servletRequest.getAttribute("start");
        servletRequest.removeAttribute("start");
        long end = System.nanoTime();
        HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;
        String url = httpServletRequest.getRequestURI();
        System.out.println("url【"+url+"】請求時間【"+(end - start)/1000 +"】s");
    }

    @Override
    public void requestInitialized(ServletRequestEvent arg0) {
        // TODO Auto-generated method stub
        ServletRequest  servletRequest  = arg0.getServletRequest();
        /*提供相對精確的計時，但是不能用他來計算當前日期*/
        servletRequest.setAttribute("start", System.nanoTime());
    }

}