检查是否有相关程序运行 action

public static boolean isIntentAvailable(Context context, String action) {
    final PackageManager packageManager = context.getPackageManager();
    final Intent intent = new Intent(action);
    List list =
            packageManager.queryIntentActivities(intent,
                    PackageManager.MATCH_DEFAULT_ONLY);
    return list.size() > 0;
}

final boolean scanAvailable = isIntentAvailable(this,
        "com.google.zxing.client.android.SCAN");