com.github.peholmst.springsecuritydemo.VersionInfo.java Source code

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Here is the source code for com.github.peholmst.springsecuritydemo.VersionInfo.java

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/*
 * Copyright (c) 2010 The original author(s)
 *
 * 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.github.peholmst.springsecuritydemo;

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

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Utility class that looks up the application version from a file named
 * <code>version.properties</code> that should be found in the root of the
 * classpath. The file is expected to have a property named
 * <code>app.version</code> that contains the version string. The file itself
 * could be generated during build time.
 * 
 * @author Petter Holmstrm
 */
public class VersionInfo {

    private static final Log logger = LogFactory.getLog(VersionInfo.class);

    private static String version = null;

    /**
     * Gets the current version of this application.
     * 
     * @return the application version string (never <code>null</code>).
     */
    public static String getApplicationVersion() {
        if (version == null) {
            readApplicationVersion();
        }
        return version;
    }

    private static void readApplicationVersion() {
        if (logger.isDebugEnabled()) {
            logger.debug("Attempting to read application version from 'version.properties'");
        }
        InputStream is = VersionInfo.class.getResourceAsStream("/version.properties");
        if (is != null) {
            Properties props = new Properties();
            try {
                props.load(is);
                version = props.getProperty("app.version");
                if (version != null) {
                    if (logger.isInfoEnabled()) {
                        logger.info("Application version is '" + version + "'");
                    }
                    return;
                }
            } catch (IOException e) {
                if (logger.isErrorEnabled()) {
                    logger.error("Could not load version properties", e);
                }
            }
        }
        if (logger.isWarnEnabled()) {
            logger.warn("Could not retrieve a version number, using 'unversioned'");
        }
        version = "unversioned";
    }

}