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");    
   }
}
 

更多内容请见原文，原文转载自：https://blog.csdn.net/qq_44638460/article/details/104106474