baseajaxobserver.java

这是AJAX的一个HTML实现！ HTML标签AJAX的实现！

/**
 * Copyright 2007 Jens Kapitza
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.sourceforge.ajaxtags.server;

import java.util.Observable;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.sourceforge.ajaxtags.servlets.BaseAjaxServlet;
import net.sourceforge.ajaxtags.xml.AjaxXmlBuilder;


/**
 * ein Observer erstellen
 * 
 * @author Jens Kapitza
 * @version $Revision$ $Date: 2007/08/01 15:21:29 $ $Author: jenskapitza $
 * 
 */
public abstract class BaseAjaxObserver extends BaseAjaxServlet implements
		ICallbackClient {

	private boolean interrupt;

	public boolean isInterrupted() {
		return this.interrupt;
	}

	private AjaxXmlBuilder xml = null;

	@Override
	public String getXmlContent(HttpServletRequest request,
			HttpServletResponse response) throws Exception {
		this.xml = null; // daten zurücksetzen

		try {
			this.interrupt = false;
			catchClient(request);
		} catch (InterruptedException e) {
			this.interrupt = true;
		}

		if (isInterrupted() || this.xml == null) {
			return null; // wenn ich beendet werde dann muss ich nichts
			// senden, da ich nichts habe!
		}
		return this.xml.toString();
	}

	/**
	 * set an xml builder
	 * 
	 * @param xml
	 */
	public void setXml(AjaxXmlBuilder xml) {
		this.xml = xml;
	}

	public void update(Observable o, Object arg) {
		if (o == null || arg == null || !(arg instanceof AjaxXmlBuilder)) {
			throw new NullPointerException();
		}
		setXml((AjaxXmlBuilder) arg);
	}

}