C#根据URL返回域名

根据给定的网页url地址返回域名

/* 
** Method 1 (using the build-in Uri-object)
*/
public static string ExtractDomainNameFromURL_Method1(string Url)
{
    if (!Url.Contains("://"))
        Url = "http://" + Url;
 
    return new Uri(Url).Host;
}
 
/*
** Method 2 (using string modifiers)
*/
public static string ExtractDomainNameFromURL_Method2(string Url)
{
    if (Url.Contains(@"://"))
        Url = Url.Split(new string[] { "://" }, 2, StringSplitOptions.None)[1];
 
    return Url.Split('/')[0];
}
 
/*
** Method 3 (using regular expressions -> slowest) 
*/
public static string ExtractDomainNameFromURL_Method3(string Url)
{
    return System.Text.RegularExpressions.Regex.Replace(
        Url, 
        @"^([a-zA-Z]+:\/\/)?([^\/]+)\/.*?$", 
        "$2"
    );
}
//使用范例：
// Some example urls:
string[] Urls = new string[] {
    "http://www.jonasjohn.de/snippets/csharp/",
    "www.jonasjohn.de/snippets/csharp/",
    "http://www.jonasjohn.de/",
    "ftp://www.jonasjohn.de/",
    "www.jonasjohn.de/",
    "http://www.75271.com/codes/",
    "https://subdomain.abc.def.jonasjohn.de/test.htm"
};
 
// Test all urls with all different methods:
foreach (string Url in Urls){
    Console.WriteLine("Method 1: {0}", ExtractDomainNameFromURL_Method1(Url));
    Console.WriteLine("Method 2: {0}", ExtractDomainNameFromURL_Method2(Url));
    Console.WriteLine("Method 3: {0}", ExtractDomainNameFromURL_Method3(Url));
}