VersionInfoUtils.java

/*
 * Copyright 2010 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 * 
 *  http://aws.amazon.com/apache2.0
 * 
 * or in the "license" file accompanying this file. This file 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.amazonaws.util;

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

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

/**
 * Utility class for accessing AWS SDK versioning information.
 */
public class VersionInfoUtils {
    
    /** The AWS SDK version info file with SDK versioning info */
    private static final String VERSION_INFO_FILE = "com/amazonaws/sdk/versionInfo.properties";
    
    /** SDK version info */
    private static String version = null;

    /** SDK platform info */
    private static String platform = null;

    /** User Agent info */
    private static String userAgent = null;

    /** Shared logger for any issues while loading version information */
    private static Log log = LogFactory.getLog(VersionInfoUtils.class);

    /**
     * Returns the current version for the AWS SDK in which this class is
     * running. Version information is obtained from from the
     * versionInfo.properties file which the AWS Java SDK build process
     * generates.
     * 
     * @return The current version for the AWS SDK, if known, otherwise
     *         returns a string indicating that the version information is
     *         not available.
     */
    public static String getVersion() {
        if (version == null) {
            initializeVersion();
        }
        
        return version;
    }

    /**
     * Returns the current platform for the AWS SDK in which this class is
     * running. Version information is obtained from from the
     * versionInfo.properties file which the AWS Java SDK build process
     * generates.
     *
     * @return The current platform for the AWS SDK, if known, otherwise
     *         returns a string indicating that the platform information is
     *         not available.
     */
    public static String getPlatform() {
        if (platform == null) {
            initializeVersion();
        }
        
        return platform;
    }

     /**
     * @return Returns the User Agent string to be used when communicating with
	 * the AWS services.  The User Agent encapsulates SDK, Java, OS and
	 * region information.
     */
    public static String getUserAgent() {
        if (userAgent == null) {
            initializeUserAgent();
        }
        
        return userAgent;
    }

   /**
     * Loads the versionInfo.properties file from the AWS Java SDK and
     * stores the information so that the file doesn't have to be read the
     * next time the data is needed.
     */
    private static void initializeVersion() {
        InputStream inputStream = VersionInfoUtils.class.getClassLoader().getResourceAsStream(VERSION_INFO_FILE);
        Properties versionInfoProperties = new Properties();
        try {
            if (inputStream == null)
                throw new Exception(VERSION_INFO_FILE + " not found on classpath");
            
            versionInfoProperties.load(inputStream);
            version = versionInfoProperties.getProperty("version");
            platform = versionInfoProperties.getProperty("platform");
        } catch (Exception e) {
            log.info("Unable to load version information for the running SDK: " + e.getMessage());
            version = "unknown-version";
            platform = "java";
        }
    }
			
   /**
     * Loads the versionInfo.properties file from the AWS Java SDK and
     * stores the information so that the file doesn't have to be read the
     * next time the data is needed.
     */
	private static void initializeUserAgent() {
		StringBuilder buffer = new StringBuilder( 1024 );
		buffer.append( "aws-sdk-" + VersionInfoUtils.getPlatform().toLowerCase() + "/" );
		buffer.append( VersionInfoUtils.getVersion() );
		buffer.append( " " );
		buffer.append( System.getProperty( "os.name" ).replace( ' ', '_' ) + "/" + System.getProperty( "os.version" ).replace( ' ', '_' ) );
		buffer.append( " " );
		buffer.append( System.getProperty( "java.vm.name" ).replace( ' ', '_' ) + "/" + System.getProperty( "java.vm.version" ).replace( ' ', '_' ) );
		
		String region = "";
		try {
			region = " " + System.getProperty( "user.language" ).replace( ' ', '_' ) + "_" + System.getProperty( "user.region" ).replace( ' ', '_' );
		}
		catch ( Exception exception ) {
		}
		
		buffer.append( region );
	
		userAgent = buffer.toString();
	}
}