Create a sane user agent string for network enabled Android applications.

HttpUtils.java

/*
 * Copyright 2013 Tristan Waddington. 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.
 * 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.
 */

public class HttpUtils {
    private static String sUserAgent;
    
    private HttpUtils() {
        // Pass
    }

    /**
     * Returns a User-Agent String in the format "App/Version (Android 4.3; Nexus 4 Build/JWR66Y)"
     */
    public static String getUserAgent(String appName, String appVersion) {
        if (sUserAgent == null) {
            synchronized (HttpUtils.class) {
                if (sUserAgent == null) {
                    sUserAgent = String.format("%s/%s (Android %s; %s Build/%s)",
                        appName, appVersion, Build.VERSION.RELEASE, Build.MODEL, Build.DISPLAY);
                }
            }
        }
        return sUserAgent;
    }
}