验证字符串是否是有效的电子邮件地址的最优雅的代码是什么?


当前回答

There are a lot of strong answers here. However, I recommend that we take a step back. @Cogwheel answers the question https://stackoverflow.com/a/1374644/388267. Nevertheless, it could be costly in a bulk validation scenario, if many of the email address being validated are invalid. I suggest that we employ a bit of logic before we enter into his try-catch block. I know that the following code could be written using RegEx but that could be costly for new developers to understand. This is my twopence worth:

    public static bool IsEmail(this string input)
    {
        if (string.IsNullOrWhiteSpace(input)) return false;

        // MUST CONTAIN ONE AND ONLY ONE @
        var atCount = input.Count(c => c == '@');
        if (atCount != 1) return false;

        // MUST CONTAIN PERIOD
        if (!input.Contains(".")) return false;

        // @ MUST OCCUR BEFORE LAST PERIOD
        var indexOfAt = input.IndexOf("@", StringComparison.Ordinal);
        var lastIndexOfPeriod = input.LastIndexOf(".", StringComparison.Ordinal);
        var atBeforeLastPeriod = lastIndexOfPeriod > indexOfAt;
        if (!atBeforeLastPeriod) return false;

        // CODE FROM COGWHEEL'S ANSWER: https://stackoverflow.com/a/1374644/388267 
        try
        {
            var addr = new System.Net.Mail.MailAddress(input);
            return addr.Address == input;
        }
        catch
        {
            return false;
        }
    }

其他回答

我用的是单线法,它对我有用

using System.ComponentModel.DataAnnotations;
public bool IsValidEmail(string source)
{
    return new EmailAddressAttribute().IsValid(source);
}

根据注释,如果源(电子邮件地址)为空,这将“失败”。

public static bool IsValidEmailAddress(this string address) => address != null && new EmailAddressAttribute().IsValid(address);

电子邮件地址验证并不像看起来那么简单。实际上,从理论上讲,仅使用正则表达式完全验证电子邮件地址是不可能的。

请查看我的博客文章,了解关于这个主题的讨论以及使用FParsec的f#实现。[/ shameless_plug]

来自@齿轮的投票最多的答案是最好的答案,但我已经尝试实现trim()字符串方法,因此它将从字符串开始到结束修剪所有用户空白。检查代码下面的完整示例-

bool IsValidEmail(string email)
{
    try
    {
        email = email.Trim();
        var addr = new System.Net.Mail.MailAddress(email);
        return addr.Address == email;
    }
    catch
    {
        return false;
    }
}

我经常用这个来验证电子邮件,它就像一个魅力。这验证了电子邮件必须在@之前至少有一个字符,并且在“”之前至少有一个字符。

public static bool ValidateEmail(string value, bool required, int minLength, int maxLength)
        {
           value = value.Trim();
           if (required == false && value == "") return true;
           if (required && value == "") return false;
           if (value.Length < minLength || value.Length > maxLength) return false;

           //Email must have at least one character before an @, and at least one character before the .
           int index = value.IndexOf('@');
           if (index < 1 || value.LastIndexOf('.') < index + 2) return false;
           return true;
        }

基于@Cogwheel的回答,我想分享一个修改后的解决方案,适用于SSIS和“脚本组件”:

Place the "Script Component" into your Data Flow connect and then open it. In the section "Input Columns" set the field that contains the E-Mail Adresses to "ReadWrite" (in the example 'fieldName'). Switch back to the section "Script" and click on "Edit Script". Then you need to wait after the code opens. Place this code in the right method: public override void Input0_ProcessInputRow(Input0Buffer Row) { string email = Row.fieldName; try { System.Net.Mail.MailAddress addr = new System.Net.Mail.MailAddress(email); Row.fieldName= addr.Address.ToString(); } catch { Row.fieldName = "WRONGADDRESS"; } }

然后,您可以使用条件分割过滤掉所有无效记录或任何您想做的事情。