notepadlogger.java

来自「JAVA Servlet2.3外文书籍源码」· Java 代码 · 共 50 行

package sessions;

import javax.servlet.ServletContext;
import javax.servlet.http.*;

/**
 * Implements HttpSessionAttributeListener to handle events associated
 * with binding/unbinding attributes to session.
 */
public class NotePadLogger implements HttpSessionAttributeListener 
{
    // Called when an attribute is added to the session
    public void attributeAdded(HttpSessionBindingEvent event)
    {
	String name = event.getName();
	if(name.equals("email")) {
	    String email = (String) event.getValue();
	    log(event, "User " + email + " started.");
	}
    }

    // Called when an attribute is deleted from the session
    public void attributeRemoved(HttpSessionBindingEvent event)
    {
	String name = event.getName();
	if(name.equals("email")) {
	    String email = (String) event.getValue();
	    log(event, "User " + email + " exited.");
	}
    }

    // Called when an attribute is replaced from the session
    public void attributeReplaced(HttpSessionBindingEvent event)
    {
	String name = event.getName();
	if(name.equals("email")) {
	    String email = (String) event.getValue();
	    log(event, "User " + email + " exited.");
	}
    }

    // Logs a message to the container log
    private void log(HttpSessionBindingEvent event, String string)
    {
	HttpSession session = event.getSession();
	ServletContext context = session.getServletContext();
	context.log(string);
    }
}