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
如果您将多个解决方案组合在一起来编写完美的代码呢?
我得到了排名最高的2个解决方案和评论，并结合起来得到更准确的答案。 它的短，快和可爱。
public static bool isValidEmail(string email)
{
try
{
var addr = new System.Net.Mail.MailAddress(email);
if (addr.Address == 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;
}
return false;
}
catch
{
return false;
}
}
其他回答
正如在许多回答中提到的，电子邮件地址的领域是复杂的。在这种情况下，我强烈反对使用正则表达式。那些匹配(大多数)用例的异常复杂，难以读取，因此也难以维护。此外，它们仍然难以支持所有病例，而且速度缓慢。
微软的EmailAddress类在这方面有所帮助，但我认为也不是完美的。在几年前的一个开源项目中，我尝试使用定制的EmailParser。
在[EmailAddress]https://github.com/Qowaiv/Qowaiv/blob/master/src/Qowaiv/EmailAddress.cs中使用。
通过使用这种方法，不仅可以验证电子邮件地址，还可以清除显示名称的多种格式，去掉mailto:-前缀，并根据ip地址规范化域字面量，并将所有内容小写(注意，本地部分是大小写敏感的)。
你的解决方案应该支持的场景(上面提到的就是):
[TestCase(null)]
[TestCase("")]
[TestCase("..@test.com")]
[TestCase(".a@test.com")]
[TestCase("ab@sd@dd")]
[TestCase(".@s.dd")]
[TestCase("ab@988.120.150.10")]
[TestCase("ab@120.256.256.120")]
[TestCase("ab@120.25.1111.120")]
[TestCase("ab@[188.120.150.10")]
[TestCase("ab@188.120.150.10]")]
[TestCase("ab@[188.120.150.10].com")]
[TestCase("a@b.-de.cc")]
[TestCase("a@bde-.cc")]
[TestCase("a@bde.c-c")]
[TestCase("a@bde.cc.")]
[TestCase("ab@b+de.cc")]
[TestCase("a..b@bde.cc")]
[TestCase("_@bde.cc,")]
[TestCase("plainaddress")]
[TestCase("plain.address")]
[TestCase("@%^%#$@#$@#.com")]
[TestCase("@domain.com")]
[TestCase("Joe Smith <email@domain.com>")]
[TestCase("email.domain.com")]
[TestCase("email@domain@domain.com")]
[TestCase(".email@domain.com")]
[TestCase("email.@domain.com")]
[TestCase("email..email@domain.com")]
[TestCase("email@-domain.com")]
[TestCase("email@domain-.com")]
[TestCase("email@domain.com-")]
[TestCase("email@.domain.com")]
[TestCase("email@domain.com.")]
[TestCase("email@domain..com")]
[TestCase("email@111.222.333")]
[TestCase("email@111.222.333.256")]
[TestCase("email@[123.123.123.123")]
[TestCase("email@[123.123.123].123")]
[TestCase("email@123.123.123.123]")]
[TestCase("email@123.123.[123.123]")]
[TestCase("email@{leftbracket.com")]
[TestCase("email@rightbracket}.com")]
[TestCase("email@p|pe.com")]
[TestCase("isis@100%.nl")]
[TestCase("email@dollar$.com")]
[TestCase("email@r&d.com")]
[TestCase("email@#hash.com")]
[TestCase("email@wave~tilde.com")]
[TestCase("email@exclamation!mark.com")]
[TestCase("email@question?mark.com")]
[TestCase("email@obelix*asterisk.com")]
[TestCase("email@grave`accent.com")]
[TestCase("email@colon:colon.com")]
[TestCase("email@caret^xor.com")]
[TestCase("email@=qowaiv.com")]
[TestCase("email@plus+.com")]
[TestCase("email@domain.com>")]
[TestCase("email( (nested) )@plus.com")]
[TestCase("email)mirror(@plus.com")]
[TestCase("email@plus.com (not closed comment")]
[TestCase("email(with @ in comment)plus.com")]
[TestCase(@"""Joe Smith email@domain.com")]
[TestCase(@"""Joe Smith' email@domain.com")]
[TestCase(@"""Joe Smith""email@domain.com")]
[TestCase("email@mailto:domain.com")]
[TestCase("mailto:mailto:email@domain.com")]
[TestCase("Display Name <email@plus.com> (after name with display)")]
[TestCase("ReDoSaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa@aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")]
public void IsInvalid(string email)
{
Assert.IsFalse(EmailAddress.IsValid(email), email);
}
[TestCase("w@com")]
[TestCase("w.b.f@test.com")]
[TestCase("w.b.f@test.museum")]
[TestCase("a.a@test.com")]
[TestCase("ab@288.120.150.10.com")]
[TestCase("ab@188.120.150.10")]
[TestCase("ab@1.0.0.10")]
[TestCase("ab@120.25.254.120")]
[TestCase("ab@01.120.150.1")]
[TestCase("ab@88.120.150.021")]
[TestCase("ab@88.120.150.01")]
[TestCase("ab@[120.254.254.120]")]
[TestCase("local@2001:0db8:85a3:0000:0000:8a2e:0370:7334")]
[TestCase("local@[2001:0db8:85a3:0000:0000:8a2e:0370:7334]")]
[TestCase("2@bde.cc")]
[TestCase("-@bde.cc")]
[TestCase("a2@bde.cc")]
[TestCase("a-b@bde.cc")]
[TestCase("ab@b-de.cc")]
[TestCase("a+b@bde.cc")]
[TestCase("f.f.f@bde.cc")]
[TestCase("ab_c@bde.cc")]
[TestCase("_-_@bde.cc")]
[TestCase("k.haak@12move.nl")]
[TestCase("K.HAAK@12MOVE.NL")]
[TestCase("email@domain.com")]
[TestCase("email@domain")]
[TestCase("あいうえお@domain.com")]
[TestCase("local@あいうえお.com")]
[TestCase("firstname.lastname@domain.com")]
[TestCase("email@subdomain.domain.com")]
[TestCase("firstname+lastname@domain.com")]
[TestCase("email@123.123.123.123")]
[TestCase("email@[123.123.123.123]")]
[TestCase("1234567890@domain.com")]
[TestCase("a@domain.com")]
[TestCase("a.b.c.d@domain.com")]
[TestCase("aap.123.noot.mies@domain.com")]
[TestCase("1@domain.com")]
[TestCase("email@domain-one.com")]
[TestCase("_______@domain.com")]
[TestCase("email@domain.topleveldomain")]
[TestCase("email@domain.co.jp")]
[TestCase("firstname-lastname@domain.com")]
[TestCase("firstname-lastname@d.com")]
[TestCase("FIRSTNAME-LASTNAME@d--n.com")]
[TestCase("first-name-last-name@d-a-n.com")]
[TestCase("{local{name{{with{@leftbracket.com")]
[TestCase("}local}name}}with{@rightbracket.com")]
[TestCase("|local||name|with|@pipe.com")]
[TestCase("%local%%name%with%@percentage.com")]
[TestCase("$local$$name$with$@dollar.com")]
[TestCase("&local&&name&with&$@amp.com")]
[TestCase("#local##name#with#@hash.com")]
[TestCase("~local~~name~with~@tilde.com")]
[TestCase("!local!!name!with!@exclamation.com")]
[TestCase("?local??name?with?@question.com")]
[TestCase("*local**name*with*@asterisk.com")]
[TestCase("`local``name`with`@grave-accent.com")]
[TestCase("^local^^name^with^@xor.com")]
[TestCase("=local==name=with=@equality.com")]
[TestCase("+local++name+with+@equality.com")]
[TestCase("Joe Smith <email@domain.com>")]
[TestCase("email@domain.com (joe Smith)")]
[TestCase(@"""Joe Smith"" email@domain.com")]
[TestCase(@"""Joe\\tSmith"" email@domain.com")]
[TestCase(@"""Joe\""Smith"" email@domain.com")]
[TestCase(@"Test |<gaaf <email@domain.com>")]
[TestCase("MailTo:casesensitve@domain.com")]
[TestCase("mailto:email@domain.com")]
[TestCase("Joe Smith <mailto:email@domain.com>")]
[TestCase("Joe Smith <mailto:email(with comment)@domain.com>")]
[TestCase(@"""With extra < within quotes"" Display Name<email@domain.com>")]
[TestCase("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa@aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")]
public void IsValid(string email)
{
Assert.IsTrue(EmailAddress.IsValid(email), email);
}
最优雅的方法是使用. net的内置方法。
这些方法:
都是经过考验的。我在自己的专业项目中使用了这些方法。 内部使用正则表达式，这是可靠和快速的。 由微软为c#编写。没有必要做重复的工作。 返回bool类型的结果。True表示邮件有效。
适用于。net 4.5及以上版本的用户
将此引用添加到项目中:
System.ComponentModel.DataAnnotations
现在你可以使用下面的代码:
(new EmailAddressAttribute().IsValid("youremailhere@test.test"));
使用实例
下面是一些需要声明的方法:
protected List<string> GetRecipients() // Gets recipients from TextBox named `TxtRecipients`
{
List<string> MethodResult = null;
try
{
List<string> Recipients = TxtRecipients.Text.Replace(",",";").Replace(" ", "").Split(';').ToList();
List<string> RecipientsCleaned = new List<string>();
foreach (string Recipient in RecipientsCleaned)
{
if (!String.IsNullOrWhiteSpace(Recipient))
{
RecipientsNoBlanks.Add(Recipient);
}
}
MethodResult = RecipientsNoBlanks;
}
catch//(Exception ex)
{
//ex.HandleException();
}
return MethodResult;
}
public static bool IsValidEmailAddresses(List<string> recipients)
{
List<string> InvalidAddresses = GetInvalidEmailAddresses(recipients);
return InvalidAddresses != null && InvalidAddresses.Count == 0;
}
public static List<string> GetInvalidEmailAddresses(List<string> recipients)
{
List<string> MethodResult = null;
try
{
List<string> InvalidEmailAddresses = new List<string>();
foreach (string Recipient in recipients)
{
if (!(new EmailAddressAttribute().IsValid(Recipient)) && !InvalidEmailAddresses.Contains(Recipient))
{
InvalidEmailAddresses.Add(Recipient);
}
}
MethodResult = InvalidEmailAddresses;
}
catch//(Exception ex)
{
//ex.HandleException();
}
return MethodResult;
}
.．.以及演示它们的代码:
List<string> Recipients = GetRecipients();
bool IsValidEmailAddresses = IsValidEmailAddresses(Recipients);
if (IsValidEmailAddresses)
{
//Emails are valid. Your code here
}
else
{
StringBuilder sb = new StringBuilder();
sb.Append("The following addresses are invalid:");
List<string> InvalidEmails = GetInvalidEmailAddresses(Recipients);
foreach (string InvalidEmail in InvalidEmails)
{
sb.Append("\n" + InvalidEmail);
}
MessageBox.Show(sb.ToString());
}
另外，这个例子:
扩展超出规范，因为一个字符串用于包含0，一个或多个由分号分隔的电子邮件地址; 清楚地演示了如何使用EmailAddressAttribute对象的IsValid方法。
对于.Net 4.5以下版本的用户，可以选择
对于.Net 4.5不可用的情况，我使用以下解决方案:
具体来说，我使用:
public static bool IsValidEmailAddress(string emailAddress)
{
bool MethodResult = false;
try
{
MailAddress m = new MailAddress(emailAddress);
MethodResult = m.Address == emailAddress;
}
catch //(Exception ex)
{
//ex.HandleException();
}
return MethodResult;
}
public static List<string> GetInvalidEmailAddresses(List<string> recipients)
{
List<string> MethodResult = null;
try
{
List<string> InvalidEmailAddresses = new List<string>();
foreach (string Recipient in recipients)
{
if (!IsValidEmail(Recipient) && !InvalidEmailAddresses.Contains(Recipient))
{
InvalidEmailAddresses.Add(Recipient);
}
}
MethodResult = InvalidEmailAddresses;
}
catch //(Exception ex)
{
//ex.HandleException();
}
return MethodResult;
}
我只是想指出，最近在. net文档中增加了关于电子邮件验证的内容，也使用了Regex操作。 关于它们实现的详细解释可以在那里找到。
https://learn.microsoft.com/en-us/dotnet/standard/base-types/how-to-verify-that-strings-are-in-valid-email-format
为了方便起见，下面是他们的测试结果:
// Valid: david.jones@proseware.com
// Valid: d.j@server1.proseware.com
// Valid: jones@ms1.proseware.com
// Invalid: j.@server1.proseware.com
// Valid: j@proseware.com9
// Valid: js#internal@proseware.com
// Valid: j_9@[129.126.118.1]
// Invalid: j..s@proseware.com
// Invalid: js*@proseware.com
// Invalid: js@proseware..com
// Valid: js@proseware.com9
// Valid: j.s@server1.proseware.com
// Valid: "j\"s\""@proseware.com
// Valid: js@contoso.中国
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;
}
}
}
如果你真的，我是说真的想知道一个电子邮件地址是否有效……请邮件交换器来证明它，不需要正则表达式。如果需要，我可以提供代码。
一般步骤如下: 1. 电子邮件地址有域名部分吗?(@ > 0的索引) 2. 使用DNS查询询问域是否有邮件交换器 3.打开到邮件交换器的TCP连接 4. 使用SMTP协议，以电子邮件地址作为接收者打开到服务器的消息 5. 解析服务器的响应。 6. 如果你能走到这一步，就别发短信了，一切都好。
正如您可以想象的那样，这是非常昂贵的时间，并且依赖于smtp，但它确实有效。
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