AbstractMessageDefinition.java

/*
 * Copyright (c) 2012 Data Harmonisation Panel
 * 
 * All rights reserved. This program and the accompanying materials are made
 * available under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the License,
 * or (at your option) any later version.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution. If not, see <http://www.gnu.org/licenses/>.
 * 
 * Contributors:
 *     HUMBOLDT EU Integrated Project #030962
 *     Data Harmonisation Panel <http://www.dhpanel.eu>
 */

package eu.esdihumboldt.hale.common.core.report.impl;

import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.Properties;

import de.fhg.igd.slf4jplus.ALogger;
import de.fhg.igd.slf4jplus.ALoggerFactory;
import eu.esdihumboldt.hale.common.core.report.Message;
import eu.esdihumboldt.hale.common.core.report.MessageDefinition;
import eu.esdihumboldt.util.definition.ObjectDefinition;

/**
 * Abstract message definition
 * 
 * @param <T> the message type
 * @author Simon Templer
 */
public abstract class AbstractMessageDefinition<T extends Message> implements MessageDefinition<T> {

	private static final ALogger log = ALoggerFactory.getLogger(AbstractMessageDefinition.class);

	private final Class<T> messageClass;

	private final String identifier;

	/**
	 * Key for the message string
	 */
	public static final String KEY_MESSAGE = "message";

	/**
	 * Key for the stack trace
	 */
	public static final String KEY_STACK_TRACE = "stack";

	/**
	 * Create message definition
	 * 
	 * @param messageClass the message class
	 * @param id the identifier for the definition (without prefix)
	 */
	public AbstractMessageDefinition(Class<T> messageClass, String id) {
		super();

		this.messageClass = messageClass;
		this.identifier = ID_PREFIX + id.toUpperCase();
	}

	/**
	 * @see ObjectDefinition#getIdentifier()
	 */
	@Override
	public String getIdentifier() {
		return identifier;
	}

	/**
	 * @see ObjectDefinition#getObjectClass()
	 */
	@Override
	public Class<T> getObjectClass() {
		return messageClass;
	}

	/**
	 * @see ObjectDefinition#parse(String)
	 */
	@Override
	public T parse(String value) {
		Properties props = new Properties();
		StringReader reader = new StringReader(value.trim());
		try {
			props.load(reader);
		} catch (IOException e) {
			log.error("Error loading message properties", e);
			return null;
		} finally {
			reader.close();
		}

		return createMessage(props);
	}

	/**
	 * Create a message from a set of properties
	 * 
	 * @param props the properties
	 * @return the message
	 */
	protected abstract T createMessage(Properties props);

	/**
	 * @see ObjectDefinition#asString(Object)
	 */
	@Override
	public String asString(T message) {
		String nl = System.getProperty("line.separator");
		Properties props = asProperties(message);

		StringWriter writer = new StringWriter();
		try {
			props.store(writer, null);
		} catch (IOException e) {
			throw new IllegalStateException(e);
		} finally {
			try {
				writer.close();
			} catch (IOException e) {
				// ignore
			}
		}

		return nl + writer.toString() + nl + nl;
	}

	/**
	 * Get a {@link Properties} representation of the given message that can be
	 * used to create a new message instance using
	 * {@link #createMessage(Properties)}.
	 * 
	 * @param message the message
	 * @return the properties representing the message
	 */
	protected Properties asProperties(T message) {
		Properties props = new Properties();

		String msg = message.getMessage();
		if (msg == null) {
			msg = "null";
		}
		props.setProperty(KEY_MESSAGE, msg);

		if (message.getStackTrace() != null) {
			props.setProperty(KEY_STACK_TRACE, message.getStackTrace());
		}
		else {
			props.setProperty(KEY_STACK_TRACE, "");
		}

		return props;
	}
}