org.directwebremoting.util.VersionUtil Maven / Gradle / Ivy

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DWR is easy Ajax for Java. It makes it simple to call Java code directly from Javascript. It gets rid of almost all the boiler plate code between the web browser and your Java code.

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/*
 * Copyright 2005 Joe Walker
 *
 * 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 org.directwebremoting.util;

import java.io.InputStream;
import java.util.Properties;

/**
 * Interface to the system version info file
 * @author Joe Walker [joe at getahead dot ltd dot uk]
 */
public class VersionUtil
{
    /**
     * Fish the version number out of the dwr.properties file.
     * @return The current version number.
     */
    public static String getSourceControlInfo()
    {
        synchronized (propLock)
        {
            if (props == null)
            {
                loadProperties();
            }

            return props.getProperty(KEY_SCCINFO);
        }
    }

    /**
     * Fish the version number out of the dwr.properties file.
     * @return The current version number.
     */
    public static String getVersion()
    {
        synchronized (propLock)
        {
            if (props == null)
            {
                loadProperties();
            }

            return props.getProperty(KEY_VERSION);
        }
    }

    /**
     * Load the properties from the internal properties file.
     */
    private static void loadProperties()
    {
        synchronized (propLock)
        {
            props = new Properties();

            try
            {
                InputStream in = VersionUtil.class.getResourceAsStream(FILENAME_VERSION);
                props.load(in);
            }
            catch (Exception ex)
            {
                props.setProperty(KEY_VERSION, VALUE_UNKNOWN);
                props.setProperty(KEY_SCCINFO, VALUE_UNKNOWN);
                props.setProperty(KEY_ERROR, ex.toString());
            }
        }
    }

    private static Properties props = null;

    private static final Object propLock = new Object();

    private static final String FILENAME_VERSION = "/dwr-version.properties";

    private static final String KEY_VERSION = "version";

    private static final String KEY_SCCINFO = "scc-info";

    private static final String KEY_ERROR = "error";

    private static final String VALUE_UNKNOWN = "unknown";
}