LogMessageWriter.java

/**
 * This is free software licensed under the Terms of the GNU Public
 * license (GPL) V3 (see http://www.gnu.org/licenses/gpl-3.0.html
 * for details
 *
 * No warranty whatsoever is provided. Use at your own risk.
 *
 * @author Christoph
 */
package org.chris.portmapper.logging;

import java.io.IOException;
import java.io.Writer;
import java.util.LinkedList;
import java.util.List;

import javax.swing.JTextArea;

/**
 * The {@link LogMessageWriter} copies every written string to a
 * {@link LogMessageListener}. All written strings are buffered, so no string is
 * missed. A {@link LogMessageListener} can be registered using method
 * {@link #registerListener(JTextArea)}.
 * 
 * @author Christoph
 * @version $Id: LogMessageWriter.java 61 2009-08-15 14:58:46Z christoph $
 */
public class LogMessageWriter extends Writer {

	/**
	 * The listener to which the strings will be forwarded.
	 */
	private LogMessageListener logListener;

	/**
	 * The buffer to which the written strings are added until a listener is
	 * registered.
	 */
	private List<String> unprocessedMessagesBuffer;

	/**
	 * Creates a new {@link LogMessageWriter}. At creation time, no listener is
	 * registered, so that all added text is stored in a buffer.
	 */
	public LogMessageWriter() {
		super();
		unprocessedMessagesBuffer = new LinkedList<String>();
	}

	@Override
	public void close() throws IOException {
	}

	@Override
	public void flush() throws IOException {
	}

	@Override
	public void write(char[] cbuf, int off, int len) {
		String line = new String(cbuf, off, len);
		addMessage(line);
	}

	/**
	 * Append the given message to the registered {@link LogMessageListener}. If
	 * no listener is registered, the string is written to a buffer. When a
	 * listener is registered, the buffered text will be appended to the
	 * listener.
	 * 
	 * @param message
	 *            the message to append.
	 */
	public void addMessage(String message) {
		if (this.logListener != null) {
			this.logListener.addLogMessage(message);
		} else {
			unprocessedMessagesBuffer.add(message);
		}
	}

	/**
	 * Registers a {@link JTextArea}, so that all strings written to this writer
	 * are appended to the given text area. After registration, all buffered
	 * strings are appended to the text area, so that no string is missed.
	 * 
	 * @param textArea
	 *            the text area to wich to append the strings.
	 */
	public void registerListener(LogMessageListener textArea) {
		this.logListener = textArea;

		// append the buffered text to the text area.
		for (String line : unprocessedMessagesBuffer) {
			this.logListener.addLogMessage(line);
		}
		// we do not need the buffer any more, all text will be appended
		// to the text area.
		this.unprocessedMessagesBuffer = null;
	}
}