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
通过system . text . regulareexpressions检查电子邮件字符串的格式是否正确:
public static bool IsValidEmailId(string InputEmail)
{
Regex regex = new Regex(@"^([\w\.\-]+)@([\w\-]+)((\.(\w){2,3})+)$");
Match match = regex.Match(InputEmail);
if (match.Success)
return true;
else
return false;
}
protected void Email_TextChanged(object sender, EventArgs e)
{
String UserEmail = Email.Text;
if (IsValidEmailId(UserEmail))
{
Label4.Text = "This email is correct formate";
}
else
{
Label4.Text = "This email isn't correct formate";
}
}
我从第1条中得到Phil的答案,并创建了这个类。 这样调用它:bool isValid = Validator.EmailIsValid(emailString);
下面是这个类:
using System.Text.RegularExpressions;
public static class Validator
{
static Regex ValidEmailRegex = CreateValidEmailRegex();
/// <summary>
/// Taken from http://haacked.com/archive/2007/08/21/i-knew-how-to-validate-an-email-address-until-i.aspx
/// </summary>
/// <returns></returns>
private static Regex CreateValidEmailRegex()
{
string validEmailPattern = @"^(?!\.)(""([^""\r\\]|\\[""\r\\])*""|"
+ @"([-a-z0-9!#$%&'*+/=?^_`{|}~]|(?<!\.)\.)*)(?<!\.)"
+ @"@[a-z0-9][\w\.-]*[a-z0-9]\.[a-z][a-z\.]*[a-z]$";
return new Regex(validEmailPattern, RegexOptions.IgnoreCase);
}
internal static bool EmailIsValid(string emailAddress)
{
bool isValid = ValidEmailRegex.IsMatch(emailAddress);
return isValid;
}
}
对@齿轮回答做了一点修改
public static bool IsValidEmail(this string email)
{
// skip the exception & return early if possible
if (email.IndexOf("@") <= 0) return false;
try
{
var address = new MailAddress(email);
return address.Address == email;
}
catch
{
return false;
}
}
我认为最好的方法如下:
public static bool EmailIsValid(string email)
{
string expression = "\\w+([-+.']\\w+)*@\\w+([-.]\\w+)*\\.\\w+([-.]\\w+)*";
if (Regex.IsMatch(email, expression))
{
if (Regex.Replace(email, expression, string.Empty).Length == 0)
{
return true;
}
}
return false;
}
你可以在一个通用类中使用这个静态函数。
一般来说,使用正则表达式来验证电子邮件地址并不是一件容易的事情;在撰写本文时,电子邮件地址的语法必须遵循相对较多的标准,在正则表达式中实现所有这些标准实际上是不可行的!
我强烈建议你试试我们的EmailVerify。NET是一个成熟的。NET库,它可以根据当前所有的IETF标准(RFC 1123, RFC 2821, RFC 2822, RFC 3696, RFC 4291, RFC 5321和RFC 5322)验证电子邮件地址,测试相关的DNS记录,检查目标邮箱是否可以接受消息,甚至可以判断给定的地址是否是一次性的。
免责声明:我是这个组件的主要开发人员。
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