C#獲取本機內網外網IP

using System.Net;

# region 獲取內、外網Ip

/// <summary>
/// 獲取本地ip地址,優先取內網ip
/// </summary>
public static String GetLocalIp()
{
    String[] Ips = GetLocalIpAddress();

    foreach (String ip in Ips) if (ip.StartsWith("10.80.")) return ip;
    foreach (String ip in Ips) if (ip.Contains(".")) return ip;

    return "127.0.0.1";
}

/// <summary>
/// 獲取本地ip地址。多個ip
/// </summary>
public static String[] GetLocalIpAddress()
{
    string hostName = Dns.GetHostName();                    //獲取主機名稱  
    IPAddress[] addresses = Dns.GetHostAddresses(hostName); //解析主機IP地址  

    string[] IP = new string[addresses.Length];             //轉換為字符串形式  
    for (int i = 0; i < addresses.Length; i++) IP[i] = addresses[i].ToString();

    return IP;
}

/// <summary>
/// 獲取外網ip地址
/// </summary>
public static string GetExtenalIpAddress_0()
{
    string IP = "未獲取到外網ip";
    try
    {
        //從網址中獲取本機ip數據  
        System.Net.WebClient client = new System.Net.WebClient();
        client.Encoding = System.Text.Encoding.Default;
        string str = client.DownloadString("http://1111.ip138.com/ic.asp");
        client.Dispose();

        //提取外網ip數據 [218.104.71.178]  
        int i1 = str.IndexOf("["), i2 = str.IndexOf("]");
        IP = str.Substring(i1 + 1, i2 - 1 - i1);
    }
    catch (Exception) { }

    return IP;
}

/// <summary>
/// 獲取外網ip地址
/// </summary>
public static string GetExtenalIpAddress()
{
    String url = "http://hijoyusers.joymeng.com:8100/test/getNameByOtherIp";
    string IP = "未獲取到外網ip";
    try
    {
        //從網址中獲取本機ip數據  
        System.Net.WebClient client = new System.Net.WebClient();
        client.Encoding = System.Text.Encoding.Default;
        string str = client.DownloadString(url);
        client.Dispose();

        if (!str.Equals("")) IP = str;
        else IP = GetExtenalIpAddress_0();
    }
    catch (Exception) { }

    return IP;
}

# endregion