AdMobUtil.java

import android.content.ContentResolver;
import android.content.Context;
import android.os.Build;
import android.provider.Settings;
import android.util.Log;

import com.google.android.gms.ads.AdRequest;

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Locale;

/**
 * AdMobのaddTestDeviceを自動で行えたらいいなぁと思い実装。
 * コードの実装は PlayServices 8.4.0 の com/google/android/gms/ads/internal/util/client/zza.class の
 * デコンパイラ内容から拝借。
 */
public class AdMobUtil {
    private static final String TAG = AdMobUtil.class.getSimpleName();

    public static AdRequest.Builder addTestDeviceAutomatically(Context context, AdRequest.Builder builder) {
        String deviceID = getOwnDeviceID(context);
        Log.d(TAG, "addTestDeviceAutomatically: deviceId:" + deviceID);
        return builder.addTestDevice(deviceID);
    }

    private static String getOwnDeviceID(Context context) {
        ContentResolver cr = context.getContentResolver();
        String androidId = cr == null ? null : Settings.Secure.getString(cr, Settings.Secure.ANDROID_ID);
        return convertAndroidIdToDeviceId(androidId != null && !isGeneric() ? androidId : "emulator");
    }

    private static String convertAndroidIdToDeviceId(String androidId) {
        int i = 0;
        while (i < 2) {
            try {
                MessageDigest md5 = MessageDigest.getInstance("MD5");
                md5.update(androidId.getBytes());
                return String.format(Locale.US, "%032X", new Object[]{new BigInteger(1, md5.digest())});
            } catch (NoSuchAlgorithmException e) {
                ++i;
            }
        }
        return null;
    }

    private static boolean isGeneric() {
        return Build.DEVICE.startsWith("generic");
    }
}