Android開發系統工具類SysUtils：獲取App版本號、SD卡目錄、快取目錄、是否後臺執行、前臺可見

public class SysUtils {
    private static final String TAG = "SysUtils";
    private SysUtils() {
    }

    /**獲取版本號
     * @param context
     * @return
     */
    public static String getVersionName(Context context) {
        PackageManager pkgMng = context.getPackageManager();
        PackageInfo pkgInfo = null;
        try {
            pkgInfo = pkgMng.getPackageInfo(context.getPackageName(), 0);
        } catch (NameNotFoundException e) {
            e.printStackTrace();
        }
        return pkgInfo != null ? pkgInfo.versionName : "";
    }
    /**
     * 獲取SD卡目錄
     * @return 如果沒有SD卡就返回null
     */
    public static String getSdDir() {
        boolean sdCardExist = Environment.getExternalStorageState().equals(
                Environment.MEDIA_MOUNTED); // 判斷sd卡是否存在
        if (sdCardExist) {
            return Environment.getExternalStorageDirectory().toString(); // 獲取目錄
        }
        return null;
    }
    /**
     * 獲取應用快取目錄
     * @param context
     * @return
     */
    public static String getCacheDir(Context context) {
        return context.getCacheDir().toString();
    }
    /**獲取應用的語言
     * @param context
     * @return
     */
    public static String getLanguage(Context context) {
        Locale locale = context.getResources().getConfiguration().locale;
        return locale.getLanguage();
    }
    /**
     * 判斷程式是否在後臺執行
     * @param context
     * @return
     */
    public static boolean isBackground(Context context) {
        ActivityManager activityManager = (ActivityManager) context
                .getSystemService(Context.ACTIVITY_SERVICE);
        List<RunningAppProcessInfo> appProcesses = activityManager
                .getRunningAppProcesses();
        for (RunningAppProcessInfo appProcess : appProcesses) {
            if (appProcess.processName.equals(context.getPackageName())) {
                if (appProcess.importance == RunningAppProcessInfo.IMPORTANCE_BACKGROUND) {
                    return true;
                } else {
                    return false;
                }
            }
        }
        return false;
    }

    /**判斷app是否前臺可見
     * @param context
     * @return
     */
    public static boolean isVisible(Context context) {
        ActivityManager activityManager = (ActivityManager) context
                .getSystemService(Context.ACTIVITY_SERVICE);
        List<RunningAppProcessInfo> appProcesses = activityManager
                .getRunningAppProcesses();
        for (RunningAppProcessInfo appProcess : appProcesses) {
            if (appProcess.processName.equals(context.getPackageName())) {
                if (appProcess.importance == RunningAppProcessInfo.IMPORTANCE_VISIBLE ||
                        appProcess.importance == RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
                    return true;
                } else {
                    return false;
                }
            }
        }
        return false;
    }
}