org.eclipse.swtbot.swt.finder.utils.MessageFormat.java Source code

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Here is the source code for org.eclipse.swtbot.swt.finder.utils.MessageFormat.java

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/*******************************************************************************
 * Copyright (c) 2008 Ketan Padegaonkar and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Ketan Padegaonkar - initial API and implementation
 *     Hans Schwaebli - http://swtbot.org/bugzilla/show_bug.cgi?id=112
 *******************************************************************************/
package org.eclipse.swtbot.swt.finder.utils;

import java.util.Arrays;
import java.util.Map;

import org.apache.commons.collections.map.LRUMap;

/**
 * Message formatter to optimize logging performance. The cost of logging is mostly in the string concatenation and
 * parameter evaluation of arguments. Log4j logs the object by invoking {@link #toString()} on the object being logged.
 * This class performs lazy evaluation of the message, only when {@link #toString()} is invoked, which happens at the
 * time of logging.
 * <p>
 * <b>Note:</b> This class uses a ThreadLocal cache instead of a single cache, since the cache would then need to be
 * synchronized since multiple threads would access it.
 * </p>
 * 
 * @author Ketan Padegaonkar &lt;KetanPadegaonkar [at] gmail [dot] com&gt;
 * @version $Id$
 */
public class MessageFormat extends ThreadLocal<Map> {

    private final String pattern;
    private final Object[] args;

    private MessageFormat(String pattern, Object... args) {
        this.pattern = pattern;
        this.args = args;
    }

    public static MessageFormat format(String s, Object... args) {
        return new MessageFormat(s, args);
    }

    public String toString() {
        try {
            return formatter(pattern).format(args);
        } catch (Exception e) {
            return "MessageFormat: Could not translate message: '" + pattern + "' using arguments " //$NON-NLS-1$//$NON-NLS-2$
                    + Arrays.asList(args);
        }
    }

    protected Map initialValue() {
        return new LRUMap(512);
    }

    @SuppressWarnings("unchecked")
    private java.text.MessageFormat formatter(String pattern) {
        java.text.MessageFormat formatter = (java.text.MessageFormat) get().get(pattern);
        if (formatter == null) {
            formatter = new java.text.MessageFormat(pattern);
            get().put(pattern, formatter);
        }
        return formatter;
    }
}