Java-ServletRequestEvent-ServletRequestAttributeEvent

  /**
      * Events of this kind indicate lifecycle
      * events for a ServletRequest.
      * The source of the event
      * is the ServletContext of this web application.
      * @see ServletRequestListener
      * @since	Servlet 2.4
      */

//ServletRequest生命周期的事件
public class ServletRequestEvent extends java.util.EventObject {
    private ServletRequest request;

    /** Construct a ServletRequestEvent for the given ServletContext
      * and ServletRequest.
      *
      * @param sc		the ServletContext of the web application.
      * @param request		the ServletRequest that is sending the event.
      */
    //构造函数，
    public ServletRequestEvent(ServletContext sc, ServletRequest request) {
        super(sc);
        this.request = request;
    }

    /**
      * Returns the ServletRequest that is changing.
      */
    public ServletRequest getServletRequest () {
        return this.request;
    }

    /**
      * Returns the ServletContext of this web application.
      */
    public ServletContext getServletContext () {
        return (ServletContext) super.getSource();
    }
}

  /**
      * This is the event class for notifications of changes to the
      * attributes of the servlet request in an application.
      * @see ServletRequestAttributeListener
      * @since	Servlet 2.4
      */

public class ServletRequestAttributeEvent extends ServletRequestEvent {
    private String name;
    private Object value;

     /** Construct a ServletRequestAttributeEvent giving the servlet context
      * of this web application, the ServletRequest whose attributes are
      * changing and the name and value of the attribute.
      *
      * @param sc		the ServletContext that is sending the event.
      * @param request		the ServletRequest that is sending the event.
      * @param name		the name of the request attribute.
      * @param value		the value of the request attribute.
      */
    public ServletRequestAttributeEvent(ServletContext sc, ServletRequest request, String name, Object value) {
        super(sc, request);
        this.name = name;
        this.value = value;
    }

    /**
      * Return the name of the attribute that changed on the ServletRequest.
      *
      * @return		the name of the changed request attribute
      */
    public String getName() {
        return this.name;
    }

    /**
      * Returns the value of the attribute that has been added, removed or
      * replaced. If the attribute was added, this is the value of the
      * attribute. If the attribute was removed, this is the value of the
      * removed attribute. If the attribute was replaced, this is the old
      * value of the attribute.
      *
      * @return		the value of the changed request attribute
      */
    public Object getValue() {
        return this.value;
    }
}