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
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;
}
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;
}
}
老实说,在产品代码中,我所做的最好的事情就是检查@符号。
我从来没有在一个地方完全验证电子邮件。你知道我怎么判断它是否有效吗?如果发送出去了。如果没有,那就糟了,如果有,生活就好了。这就是我需要知道的。
private static bool IsValidEmail(string emailAddress)
{
const 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).IsMatch(emailAddress);
}
短而准确的代码
string Email = txtEmail.Text;
if (Email.IsValidEmail())
{
//use code here
}
public static bool IsValidEmail(this string email)
{
string pattern = @"^(?!\.)(""([^""\r\\]|\\[""\r\\])*""|" + @"([-a-z0-9!#$%&'*+/=?^_`{|}~]|(?<!\.)\.)*)(?<!\.)" + @"@[a-z0-9][\w\.-]*[a-z0-9]\.[a-z][a-z\.]*[a-z]$";
var regex = new Regex(pattern, RegexOptions.IgnoreCase);
return regex.IsMatch(email);
}
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