using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using Microsoft.SharePoint;
using Microsoft.Office.Server;
namespace 获得当前用户
{
    public partial class GetEmployee : System.Web.UI.UserControl
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            SPSite spSite = new SPSite("moss的站点地址");

            SPWeb web = spSite.RootWeb;
            string userName = web.CurrentUser.Name;

            txtEmployee.Value = userName;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Text;
using System.Web.UI.WebControls.WebParts;
using System.Security.Principal;

namespace Test
{
    public class DomainUser : WebPart
    {
        protected override void Render(System.Web.UI.HtmlTextWriter writer)
        {
            //获取当前登陆用户的登陆名   
            WindowsPrincipal wp = (WindowsPrincipal)System.Threading.Thread.CurrentPrincipal;
            string wpname = wp.Identity.Name.ToString();
            int j = wpname.LastIndexOf("\\");
            string userName = wpname.Substring(j + 1);
            string domainName = wpname.Substring(0, j);
            writer.Write(domainName.ToString() + " \\ " + userName.ToString());
        }
    }
}