MessageParser.java

/*
 | Copyright 2013 Esri
 |
 | 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 com.esri.geoevent.solutions.adapter.geomessage;

import java.util.HashMap;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

public class MessageParser extends DefaultHandler
{
	private static final String MESSAGES_TAG1  = "messages";
	private static final String MESSAGE_TAG1   = "message";
	private static final String MESSAGES_TAG2  = "geomessages";
	private static final String MESSAGE_TAG2   = "geomessage";
	
	private enum MessageLevel
	{
		root, inMessages, inMessage, inAttribute;
	}

	private MessageLevel messageLevel = MessageLevel.root;

	private String attributeName;
	private String attribute;
	private HashMap<String,String> attributes = new HashMap<String,String>();
	private DefenseInboundAdapter adapter;

	public MessageParser( DefenseInboundAdapter adapter )
	{
		super();
		this.adapter = adapter;
	}

	@Override
	public void startElement(String uri, String localName,String qName,	Attributes attributes) throws SAXException
	{
		if(qName == null)
			return;

		if (messageLevel == MessageLevel.root && (qName.equalsIgnoreCase(MESSAGES_TAG1) || qName.equalsIgnoreCase(MESSAGES_TAG2)))
		{
			messageLevel = MessageLevel.inMessages;
		}
		else if(messageLevel == MessageLevel.inMessages && (qName.equalsIgnoreCase(MESSAGE_TAG1) || qName.equalsIgnoreCase(MESSAGE_TAG2)))
		{
			messageLevel = MessageLevel.inMessage;
		}
		else if(messageLevel == MessageLevel.inMessage)
		{
			messageLevel = MessageLevel.inAttribute;
			attribute = "";
			attributeName = qName;
		}
		else if(messageLevel == MessageLevel.inAttribute)
		{
			throw new SAXException("Problem parsing message, cannot handle nested attributes. ("+qName+" inside "+attributeName+")");
		}
	}

	@Override
	public void endElement(String uri, String localName, String qName) throws SAXException
	{
		if (messageLevel == MessageLevel.inMessages && (qName.equalsIgnoreCase(MESSAGES_TAG1) || qName.equalsIgnoreCase(MESSAGES_TAG2)))
		{
			messageLevel = MessageLevel.root;
		}
		else if (messageLevel == MessageLevel.inMessage && (qName.equalsIgnoreCase(MESSAGE_TAG1) || qName.equalsIgnoreCase(MESSAGE_TAG2)))
		{
			messageLevel = MessageLevel.inMessages;
			adapter.queueGeoEvent(attributes);
			attributes.clear();
		}
		else if (messageLevel == MessageLevel.inAttribute && qName.equalsIgnoreCase(attributeName))
		{
			messageLevel = MessageLevel.inMessage;
			attributes.put( attributeName, attribute );
			attributeName = null;
		}

	}

	@Override
	public void characters(char ch[], int start, int length) throws SAXException
	{
		if (messageLevel == MessageLevel.inAttribute)
		{
			attribute = new String(ch, start, length);
		}
	}

	public void setAdapter( DefenseInboundAdapter adapter )
	{
		this.adapter = adapter;
	}

}