debuglistener.java

来自「JAVA Servlet2.3外文书籍源码」· Java 代码 · 共 95 行

package debugging;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class DebugListener implements ServletContextListener,
                                      HttpSessionListener, 
                                      ServletContextAttributeListener,
                                      HttpSessionAttributeListener {

  private ServletContext servletContext=null;

  private void logContext(String message) {
    if (servletContext != null) {
      StringBuffer messageBuffer = new StringBuffer();
      messageBuffer.append("<invocation><sender>");
      messageBuffer.append(servletContext.getServerInfo());
      messageBuffer.append("</sender><message>" + message + "</message><receiver>");

      String contextName=servletContext.getServletContextName();
      if (contextName==null) contextName=servletContext.toString();

      messageBuffer.append("CONTEXT: " + contextName);

      messageBuffer.append("</receiver></invocation>");
      servletContext.log(messageBuffer.toString()); 
    }   
  }

  private void logSession(String message, HttpSessionEvent event) {
    if (servletContext != null) {
      StringBuffer messageBuffer = new StringBuffer();
      messageBuffer.append("<invocation><sender>");
      messageBuffer.append(servletContext.getServerInfo());
      messageBuffer.append("</sender><message>" + message + "</message><receiver>");
      messageBuffer.append("SESSION: " + event.getSession().getId());
      messageBuffer.append("</receiver></invocation>");
      servletContext.log(messageBuffer.toString());
    }
  }

  public void contextInitialized(ServletContextEvent event) {
    servletContext=event.getServletContext();
    logContext("init()");
  }

  public void contextDestroyed(ServletContextEvent event) {
    logContext("destroy");
    servletContext=null;
  }

  public void sessionCreated(HttpSessionEvent event) {
    logSession("create", event);
  }

  public void sessionDestroyed(HttpSessionEvent event) {
    logSession("destroy", event);
  }

  public void attributeAdded(ServletContextAttributeEvent event) {
    logContext("setAttribute(" +
               event.getName() + "," + 
               event.getValue().toString() + ")");
  }

  public void attributeReplaced(ServletContextAttributeEvent event) {
    logContext("setAttribute(" +
               event.getName() + "," + 
               event.getValue().toString() + ")");
  }

  public void attributeRemoved(ServletContextAttributeEvent event) {
    logContext("removeAttribute(" + event.getName() + ")");
  }

  public void attributeAdded(HttpSessionBindingEvent event) {
    logSession("setAttribute(" +
               event.getName() + "," +
               event.getValue().toString() + ")",
               event);
  }

  public void attributeReplaced(HttpSessionBindingEvent event) {
    logSession("setAttribute(" +
               event.getName() + "," +
               event.getValue().toString() + ")",
               event);
  }

  public void attributeRemoved(HttpSessionBindingEvent event) {
    logSession("removeAttribute(" + event.getName() + ")",
               event);
  }
}