ServletRequestAttributeListener的用法和实例

6）ServletRequestAttributeListener：

ServletRequestAttributeListener能监测到有人正在往ServletRequest里添加属性。你可以采取相应的措施。

例 2.2.6.1

package com;

import javax.servlet.ServletRequestAttributeEvent;

import javax.servlet.ServletRequestAttributeListener;

public class MyServletRequestAttributeListener implements ServletRequestAttributeListener {

public void attributeAdded(ServletRequestAttributeEvent arg0) {

System.out.println("增加了" + arg0.getName() + " " +

arg0.getValue() );

}

public void attributeRemoved(ServletRequestAttributeEvent arg0) {

System.out.println("去除了" + arg0.getName() + " " +

arg0.getValue() );

}

public void attributeReplaced(ServletRequestAttributeEvent arg0) {

System.out.println("取代了" + arg0.getName() + " " +

arg0.getValue()+"现在的新值是"+arg0.getServletRequest().getAttribute(arg0.getName()) );

}

}

web.xml加入下面这段话：

<listener>

<listener-class>com.MyServletRequestAttributeListener</listener-class>

</listener>

用下面这个servlet测试：

package com;

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class ServletHello1 extends HttpServlet {

protected void doGet(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException {

System.out.println("add attribute");

request.setAttribute("name", "马克-to-win");

System.out.println("replace attribute");

request.setAttribute("name", "mark-to-win");

System.out.println("remove attribute");

request.removeAttribute("name");

}

}

更多请看：https://blog.csdn.net/qq_44638460/article/details/104106474