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
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。
其他回答
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;
}
}
public bool IsValidEmail(string email)
{
try
{
var addr = new System.Net.Mail.MailAddress(email);
return addr.Address == email;
}
catch
{
return false;
}
}
这是一个老问题,但我在SO上找到的所有答案,包括最近的答案,都与这个问题类似。然而,在。net 4.5 / MVC 4中,你可以通过从System.ComponentModel中添加[EmailAddress]注释来向表单添加电子邮件地址验证。DataAnnotations,所以我想知道为什么我不能只使用。net的内置功能。
这似乎是可行的,而且在我看来是相当优雅的:
using System.ComponentModel.DataAnnotations;
class ValidateSomeEmails
{
static void Main(string[] args)
{
var email = new EmailAddressAttribute();
email.IsValid("someone@somewhere.com"); //true
email.IsValid("someone@somewhere.co.uk"); //true
email.IsValid("someone+tag@somewhere.net"); //true
email.IsValid("futureTLD@somewhere.fooo"); //true
email.IsValid("fdsa"); //false
email.IsValid("fdsa@"); //false
email.IsValid("fdsa@fdsa"); //false
email.IsValid("fdsa@fdsa."); //false
//one-liner
if (new EmailAddressAttribute().IsValid("someone@somewhere.com"))
return true;
}
}
我根据维基百科的规则和样本地址创建了一个电子邮件地址验证程序。对于那些不介意多看一点代码的人,这里。说实话,我不知道电子邮件地址规范中有这么多疯狂的规则。我没有完全验证主机名或ipaddress,但它仍然通过了维基百科上的所有测试用例。
using Microsoft.VisualStudio.TestTools.UnitTesting;
namespace EmailValidateUnitTests
{
[TestClass]
public class EmailValidationUnitTests
{
[TestMethod]
public void TestEmailValidate()
{
// Positive Assertions
Assert.IsTrue("prettyandsimple@example.com".IsValidEmailAddress());
Assert.IsTrue("very.common@example.com".IsValidEmailAddress());
Assert.IsTrue("disposable.style.email.with+symbol@example.com".IsValidEmailAddress());
Assert.IsTrue("other.email-with-dash@example.com".IsValidEmailAddress());
Assert.IsTrue("\"much.more unusual\"@example.com".IsValidEmailAddress());
Assert.IsTrue("\"very.unusual.@.unusual.com\"@example.com".IsValidEmailAddress()); //"very.unusual.@.unusual.com"@example.com
Assert.IsTrue("\"very.(),:;<>[]\\\".VERY.\\\"very@\\\\ \\\"very\\\".unusual\"@strange.example.com".IsValidEmailAddress()); //"very.(),:;<>[]\".VERY.\"very@\\ \"very\".unusual"@strange.example.com
Assert.IsTrue("admin@mailserver1".IsValidEmailAddress());
Assert.IsTrue("#!$%&'*+-/=?^_`{}|~@example.org".IsValidEmailAddress());
Assert.IsTrue("\"()<>[]:,;@\\\\\\\"!#$%&'*+-/=?^_`{}| ~.a\"@example.org".IsValidEmailAddress()); //"()<>[]:,;@\\\"!#$%&'*+-/=?^_`{}| ~.a"@example.org
Assert.IsTrue("\" \"@example.org".IsValidEmailAddress()); //" "@example.org (space between the quotes)
Assert.IsTrue("example@localhost".IsValidEmailAddress());
Assert.IsTrue("example@s.solutions".IsValidEmailAddress());
Assert.IsTrue("user@com".IsValidEmailAddress());
Assert.IsTrue("user@localserver".IsValidEmailAddress());
Assert.IsTrue("user@[IPv6:2001:db8::1]".IsValidEmailAddress());
Assert.IsTrue("user@[192.168.2.1]".IsValidEmailAddress());
Assert.IsTrue("(comment and stuff)joe@gmail.com".IsValidEmailAddress());
Assert.IsTrue("joe(comment and stuff)@gmail.com".IsValidEmailAddress());
Assert.IsTrue("joe@(comment and stuff)gmail.com".IsValidEmailAddress());
Assert.IsTrue("joe@gmail.com(comment and stuff)".IsValidEmailAddress());
// Failure Assertions
Assert.IsFalse("joe(fail me)smith@gmail.com".IsValidEmailAddress());
Assert.IsFalse("joesmith@gma(fail me)il.com".IsValidEmailAddress());
Assert.IsFalse("joe@gmail.com(comment and stuff".IsValidEmailAddress());
Assert.IsFalse("Abc.example.com".IsValidEmailAddress());
Assert.IsFalse("A@b@c@example.com".IsValidEmailAddress());
Assert.IsFalse("a\"b(c)d,e:f;g<h>i[j\\k]l@example.com".IsValidEmailAddress()); //a"b(c)d,e:f;g<h>i[j\k]l@example.com
Assert.IsFalse("just\"not\"right@example.com".IsValidEmailAddress()); //just"not"right@example.com
Assert.IsFalse("this is\"not\\allowed@example.com".IsValidEmailAddress()); //this is"not\allowed@example.com
Assert.IsFalse("this\\ still\\\"not\\\\allowed@example.com".IsValidEmailAddress());//this\ still\"not\\allowed@example.com
Assert.IsFalse("john..doe@example.com".IsValidEmailAddress());
Assert.IsFalse("john.doe@example..com".IsValidEmailAddress());
Assert.IsFalse(" joe@gmail.com".IsValidEmailAddress());
Assert.IsFalse("joe@gmail.com ".IsValidEmailAddress());
}
}
public static class ExtensionMethods
{
private const string ValidLocalPartChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!#$%&'*+-/=?^_`{|}~";
private const string ValidQuotedLocalPartChars = "(),:;<>@[]. ";
private const string ValidDomainPartChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-:";
private enum EmailParseMode
{
BeginLocal, Local, QuotedLocalEscape, QuotedLocal, QuotedLocalEnd, LocalSplit, LocalComment,
At,
Domain, DomainSplit, DomainComment, BracketedDomain, BracketedDomainEnd
};
public static bool IsValidEmailAddress(this string s)
{
bool valid = true;
bool hasLocal = false, hasDomain = false;
int commentStart = -1, commentEnd = -1;
var mode = EmailParseMode.BeginLocal;
for (int i = 0; i < s.Length; i++)
{
char c = s[i];
if (mode == EmailParseMode.BeginLocal || mode == EmailParseMode.LocalSplit)
{
if (c == '(') { mode = EmailParseMode.LocalComment; commentStart = i; commentEnd = -1; }
else if (c == '"') { mode = EmailParseMode.QuotedLocal; }
else if (ValidLocalPartChars.IndexOf(c) >= 0) { mode = EmailParseMode.Local; hasLocal = true; }
else { valid = false; break; }
}
else if (mode == EmailParseMode.LocalComment)
{
if (c == ')')
{
mode = EmailParseMode.Local; commentEnd = i;
// comments can only be at beginning and end of parts...
if (commentStart != 0 && ((commentEnd + 1) < s.Length) && s[commentEnd + 1] != '@') { valid = false; break; }
}
}
else if (mode == EmailParseMode.Local)
{
if (c == '.') mode = EmailParseMode.LocalSplit;
else if (c == '@') mode = EmailParseMode.At;
else if (c == '(') { mode = EmailParseMode.LocalComment; commentStart = i; commentEnd = -1; }
else if (ValidLocalPartChars.IndexOf(c) >= 0) { hasLocal = true; }
else { valid = false; break; }
}
else if (mode == EmailParseMode.QuotedLocal)
{
if (c == '"') { mode = EmailParseMode.QuotedLocalEnd; }
else if (c == '\\') { mode = EmailParseMode.QuotedLocalEscape; }
else if (ValidLocalPartChars.IndexOf(c) >= 0 || ValidQuotedLocalPartChars.IndexOf(c) >= 0) { hasLocal = true; }
else { valid = false; break; }
}
else if (mode == EmailParseMode.QuotedLocalEscape)
{
if (c == '"' || c == '\\') { mode = EmailParseMode.QuotedLocal; hasLocal = true; }
else { valid = false; break; }
}
else if (mode == EmailParseMode.QuotedLocalEnd)
{
if (c == '.') { mode = EmailParseMode.LocalSplit; }
else if (c == '@') mode = EmailParseMode.At;
else if (c == '(') { mode = EmailParseMode.LocalComment; commentStart = i; commentEnd = -1; }
else { valid = false; break; }
}
else if (mode == EmailParseMode.At)
{
if (c == '[') { mode = EmailParseMode.BracketedDomain; }
else if (c == '(') { mode = EmailParseMode.DomainComment; commentStart = i; commentEnd = -1; }
else if (ValidDomainPartChars.IndexOf(c) >= 0) { mode = EmailParseMode.Domain; hasDomain = true; }
else { valid = false; break; }
}
else if (mode == EmailParseMode.DomainComment)
{
if (c == ')')
{
mode = EmailParseMode.Domain;
commentEnd = i;
// comments can only be at beginning and end of parts...
if ((commentEnd + 1) != s.Length && (commentStart > 0) && s[commentStart - 1] != '@') { valid = false; break; }
}
}
else if (mode == EmailParseMode.DomainSplit)
{
if (ValidDomainPartChars.IndexOf(c) >= 0) { mode = EmailParseMode.Domain; hasDomain = true; }
else { valid = false; break; }
}
else if (mode == EmailParseMode.Domain)
{
if (c == '(') { mode = EmailParseMode.DomainComment; commentStart = i; commentEnd = -1; }
else if (c == '.') { mode = EmailParseMode.DomainSplit; }
else if (ValidDomainPartChars.IndexOf(c) >= 0) { hasDomain = true; }
else { valid = false; break; }
}
else if (mode == EmailParseMode.BracketedDomain)
{
if (c == ']') { mode = EmailParseMode.BracketedDomainEnd; }
else if (c == '.' || ValidDomainPartChars.IndexOf(c) >= 0) { hasDomain = true; }
else { valid = false; break; }
}
else if (mode == EmailParseMode.BracketedDomain)
{
if (c == '(') { mode = EmailParseMode.DomainComment; commentStart = i; commentEnd = -1; }
else { valid = false; break; }
}
}
bool unfinishedComment = (commentEnd == -1 && commentStart >= 0);
return hasLocal && hasDomain && valid && !unfinishedComment;
}
}
}
如果你正在使用FluentValidation,你可以写一些像这样简单的东西:
public cass User
{
public string Email { get; set; }
}
public class UserValidator : AbstractValidator<User>
{
public UserValidator()
{
RuleFor(x => x.Email).EmailAddress().WithMessage("The text entered is not a valid email address.");
}
}
// Validates an user.
var validationResult = new UserValidator().Validate(new User { Email = "açflkdj" });
// This will return false, since the user email is not valid.
bool userIsValid = validationResult.IsValid;
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