在Uri。TryCreate你可以检查Uri。Scheme查看它是否HTTP(s)。

试着验证HTTP url (uriName是你想测试的URI):

Uri uriResult;
bool result = Uri.TryCreate(uriName, UriKind.Absolute, out uriResult) 
    && uriResult.Scheme == Uri.UriSchemeHttp;

或者，如果你想同时接受有效的HTTP和HTTPS url(根据J0e3gan的评论):

Uri uriResult;
bool result = Uri.TryCreate(uriName, UriKind.Absolute, out uriResult) 
    && (uriResult.Scheme == Uri.UriSchemeHttp || uriResult.Scheme == Uri.UriSchemeHttps);

返回bool值:

Uri.IsWellFormedUriString(a.GetAttribute("href"), UriKind.Absolute)

Uri uri = null;
if (!Uri.TryCreate(url, UriKind.Absolute, out uri) || null == uri)
    return false;
else
    return true;

这里url是你要测试的字符串。

    public static bool CheckURLValid(this string source)
    {
        Uri uriResult;
        return Uri.TryCreate(source, UriKind.Absolute, out uriResult) && uriResult.Scheme == Uri.UriSchemeHttp;
    }

用法:

string url = "htts://adasd.xc.";
if(url.CheckUrlValid())
{
  //valid process
}

更新:(单行代码)谢谢@GoClimbColorado

public static bool CheckURLValid(this string source) => Uri.TryCreate(source, UriKind.Absolute, out Uri uriResult) && uriResult.Scheme == Uri.UriSchemeHttps;

用法:

string url = "htts://adasd.xc.";
if(url.CheckUrlValid())
{
  //valid process
}

此方法在http和https中都可以正常工作。只有一行:)

if (Uri.IsWellFormedUriString("https://www.google.com", UriKind.Absolute))

MSDN: IsWellFormedUriString

这里的所有答案要么允许使用其他方案的url(例如，file://， ftp://))，要么拒绝以http://或https://开头的人类可读的url(例如，www.google.com)，这在处理用户输入时并不好。

我是这样做的:

public static bool ValidHttpURL(string s, out Uri resultURI)
{
    if (!Regex.IsMatch(s, @"^https?:\/\/", RegexOptions.IgnoreCase))
        s = "http://" + s;

    if (Uri.TryCreate(s, UriKind.Absolute, out resultURI))
        return (resultURI.Scheme == Uri.UriSchemeHttp || 
                resultURI.Scheme == Uri.UriSchemeHttps);

    return false;
}

用法:

string[] inputs = new[] {
                          "https://www.google.com",
                          "http://www.google.com",
                          "www.google.com",
                          "google.com",
                          "javascript:alert('Hack me!')"
                        };
foreach (string s in inputs)
{
    Uri uriResult;
    bool result = ValidHttpURL(s, out uriResult);
    Console.WriteLine(result + "\t" + uriResult?.AbsoluteUri);
}

输出:

True    https://www.google.com/
True    http://www.google.com/
True    http://www.google.com/
True    http://google.com/
False

作为使用正则表达式的另一种方法，这段代码使用Uri。TryCreate每个OP，但也检查结果，以确保它的Scheme是http或https之一:

bool passed =
  Uri.TryCreate(url, UriKind.Absolute, out Uri uriResult)
    && (uriResult.Scheme == Uri.UriSchemeHttp
      || uriResult.Scheme == Uri.UriSchemeHttps);

试一试:

bool IsValidURL(string URL)
{
    string Pattern = @"^(?:http(s)?:\/\/)?[\w.-]+(?:\.[\w\.-]+)+[\w\-\._~:/?#[\]@!\$&'\(\)\*\+,;=.]+$";
    Regex Rgx = new Regex(Pattern, RegexOptions.Compiled | RegexOptions.IgnoreCase);
    return Rgx.IsMatch(URL);
}

它会接受这样的URL:

http (s): / / www . example . com http (s): / / stackoverflow操作。com http (s): / / www . example . com/page http (s): / / www . example . com/page ? id = 1&product = 2 http (s): / / www . example . com/page #开始 http (s) / www . example . com: 8080 http (s): / / 127 . 0 0。1 127 . 0 0。1 www.example.com 操作。com

问题:有效的url应该包括以下所有“前缀”:https, http, www

Url必须包含http://或https:// Url可能只包含一个www实例。 Url主机名类型必须为Dns Url最大长度为100

解决方案:

public static bool IsValidUrl(string webSiteUrl)
{
   if (webSiteUrl.StartsWith("www."))
   {
       webSiteUrl = "http://" + webSiteUrl;
   }
        
   return Uri.TryCreate(webSiteUrl, UriKind.Absolute, out Uri uriResult)
            && (uriResult.Scheme == Uri.UriSchemeHttp
             || uriResult.Scheme == Uri.UriSchemeHttps) && uriResult.Host.Replace("www.", "").Split('.').Count() > 1 && uriResult.HostNameType == UriHostNameType.Dns && uriResult.Host.Length > uriResult.Host.LastIndexOf(".") + 1 && 100 >= webSiteUrl.Length;
}

使用单元测试进行验证

阳性单元测验:

    [TestCase("http://www.example.com/")]
    [TestCase("https://www.example.com")]
    [TestCase("http://example.com")]
    [TestCase("https://example.com")]
    [TestCase("www.example.com")]
    public void IsValidUrlTest(string url)
    {
        bool result = UriHelper.IsValidUrl(url);

        Assert.AreEqual(result, true);
    }

单元阴性测试:

    [TestCase("http.www.example.com")]
    [TestCase("http:www.example.com")]
    [TestCase("http:/www.example.com")]
    [TestCase("http://www.example.")]
    [TestCase("http://www.example..com")]
    [TestCase("https.www.example.com")]
    [TestCase("https:www.example.com")]
    [TestCase("https:/www.example.com")]
    [TestCase("http:/example.com")]
    [TestCase("https:/example.com")]
    public void IsInvalidUrlTest(string url)
    {
        bool result = UriHelper.IsValidUrl(url);

        Assert.AreEqual(result, false);
    }

注意:IsValidUrl方法不应该验证任何相对url路径，如example.com

See:

我应该使用相对还是绝对url ?

我创建了这个函数来帮助我进行URL验证，你可以根据自己的喜好定制它，注意这是用python3.10.6编写的

def url_validator(url: str) -> bool:
    """
    use this func to filter out the urls to follow only valid urls
    :param: url
    :type: str
    :return: True if the passed url is valid otherwise return false
    :rtype: bool
    """

    #the following regex is copied from Django source code 
    # to validate a url using regax
    
    regex = re.compile(
        r"^(?:http|ftp)s?://"  # http:// or https://
        r"(?:(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+(?:[A-Z]{2,6}\.?|[A-Z0-9-]{2,}\.?)|"  # domain...
        r"localhost|"  # localhost...
        r"\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})"  # ...or ip
        r"(?::\d+)?"  # optional port
        r"(?:/?|[/?]\S+)$",
        re.IGNORECASE,
    )


    blocked_sites: list[str] = []

    for site in blocked_sites:
        if site in url or site == url:
            return False

    # if none of the above then ensure that the url is valid and then return True otherwise return False
    if re.match(regex, url):
        return True

    return False