检查C#字符串是否为具有端口号的格式正确的url

using System;
using System.Text.RegularExpressions;

public class UrlValidator
{
    private static readonly Regex UrlPattern = new Regex(
        @"^(https?|ftp):\/\/" + // 协议
        @"(?:(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+(?:[A-Z]{2,6}\.?|[A-Z0-9-]{2,}\.?)|" + // 域名
        @"localhost|" + // localhost
        @"(?:\d{1,3}\.){3}\d{1,3})" + // IP地址
        @"(?::\d+)?" + // 端口号（可选）
        @"(?:\/[^\s]*)?$", RegexOptions.IgnoreCase);

    public static bool IsValidUrl(string url)
    {
        return UrlPattern.IsMatch(url);
    }
}

class Program
{
    static void Main()
    {
        string url1 = "http://example.com:8080/path";
        string url2 = "https://localhost:3000";
        string url3 = "ftp://192.168.1.1:21";
        string url4 = "invalid-url-here";

        Console.WriteLine(UrlValidator.IsValidUrl(url1)); // 应该输出 true
        Console.WriteLine(UrlValidator.IsValidUrl(url2)); // 应该输出 true
        Console.WriteLine(UrlValidator.IsValidUrl(url3)); // 应该输出 true
        Console.WriteLine(UrlValidator.IsValidUrl(url4)); // 应该输出 false
    }
}