Question

我正在写信寻求有关为test方法实现return语句的帮助。我目前从我的test（）方法得到一个null响应，但我想知道，如何在我的"IsValidEmailDomain"方法中从"test"方法中捕获错误：

public static bool IsValidEmailDomain(MailAddress address)
{
    if (address == null) return false;
    var response = DnsClient.Default.Resolve(address.Host, RecordType.Mx);
    try
    {               
        if (response == null || response.AnswerRecords == null) return false;
    }
    catch (FormatException ex)
    {
        ex.ToString();
        throw ex;
        //return false;
    }

    return response.AnswerRecords.OfType<MxRecord>().Any();
}

public static bool IsValidEmailDomain(string address)
{
    if (string.IsNullOrWhiteSpace(address)) return false;

    MailAddress theAddress;
    try
    {
        theAddress = new MailAddress(address);
    }
    catch (FormatException)
    {
        return false;
    }

    return IsValidEmailDomain(theAddress);
}

public static string test()
{
    string mail = "########";

    if (IsValidEmailDomain(mail))
    {
        return mail;
    }
    else
    {
        ///How to return error from IsValidEmailDomain() method.
    }
}

任何提示或建议都将非常受欢迎。

Answer 1

  public static string test()
        {
            string mail = "########";
            bool? answer;
            Exception ex;
    try
    {
            answer = IsValidEmailDomain(mail);
    }
    catch(Exception e)
    {
        ex = e;
    }
            if (answer)
            {
                return mail;
            }
            else
            {
                // here you can check to see if the answer is null or if you actually got an exception
            }
        }

Answer 2

有几种方法可以做到这一点。

使用out参数。
如果出现问题，请抛出异常。（击败布尔的目的）

当我遇到这样的事情时，我通常会选择组合。

public bool IsValidEmailDomain(string email)
{
    return IsValidEmailDomain(email, false);
}

public bool IsValidEmailDomain(string email, bool throwErrorIfInvalid)
{
    string invalidMessage;
    var valid = ValidateEmailDomain(email, out invalidMessage);
    if(valid)
        return true;

    if (throwErrorIfInvalid)
        throw new Exception(invalidMessage);

    return false;
}

public bool ValidateEmailDomain(string email, out string invalidMessage)
{
    invalidMessage= null;
    if (....) // Whatever your logic is.
        return true;

    invalidMessage= "Invalid due to ....";
    return false;
}

如何从bool类型方法中捕获错误？

2 个答案: