在C#中访问AD,核对输入的用户名和密码是否正确 (转)

系统登录中，和邮件系统合并，系统本来的用户名和密码可以登录，用邮件用户密码也可以登录。

/**//// <summary>
        /// 登陆
        /// </summary>
        /// <param name="strUser">用户ID</param>
        /// <param name="strPsw">用户密码</param>
        /// <returns></returns>
        public bool Login(string strUser,string strPsw)
        {
            string SQL=" SELECT U.USERID,U.USERNAME"
                +" FROM BS_USER U "
                +" WHERE U.STATUS=0 AND U.USERID='"+strUser+"' AND USERPWD='"+strPsw+"'";
            DataTable Dt=IBSConn.getDataSet(SQL).Tables[0];    
            /**////AD 验证
            if(Dt.Rows.Count==0)
            {
                AD_China ad=new AD_China();
                if(!ad.IsAuthenticated(strUser,strPsw)) return false;
            }

            SQL=" SELECT U.USERID,U.USERNAME,U.Email,O.ORGID,O.ORGNAME,F.OrgID AS FinOrgID,F.FincName,O.ORGFORM,PRMTNAME AS ORGFORMNAME, O.NODEID,O.TREEID"
                        +",OP.OrgID ParentOrgID ,OP.OrgName ParentOrgName"
                        +" FROM BS_USER U LEFT JOIN BS_ORG O ON U.ORGID=O.ORGID"
                        +" LEFT JOIN BS_ORG OP ON O.SuperOrgID=OP.OrgID"
                        +" LEFT JOIN BS_FinanceOrg F ON O.FincID=O.FincID "                
                        +" LEFT JOIN DBO.BS_PRMT P ON P.PRMTTYPEID=1 AND PRMTID=O.ORGFORM"
                        +" WHERE U.STATUS=0 AND( U.USERID='"+strUser+"'OR U.Email='"+strUser+"')";     // 验证邮件用户密码 
            Dt=IBSConn.getDataSet(SQL).Tables[0];            
            if(Dt.Rows.Count>=1)
            {
                //其他操作
                
            }else return false;

            
            return true;

        }

AD验证类：

public class AD_China
    {
        private string _path;
        private string _filterAttribute;

        public AD_China()
        {
            //
            // TODO: 在此处添加构造函数逻辑
            //

                _path="LDAP://china.com/DC=china,DC=com";
            /**//*
            <add key="AdminUser" value="R7xM12rqyGA="/>
            <add key="AdminUserPassword" value="pZ/cZiaO9TE="/>
    */

        }


        public bool IsAuthenticated(string username, string pwd)
        {
        
            
            try
            {     
                DirectoryEntry entry = new DirectoryEntry( _path,  username, pwd);
        
                // 绑定到本机 AdsObject 以强制身份验证。 
                Object obj = entry.NativeObject;
                DirectorySearcher search = new DirectorySearcher(entry);
                search.Filter = "(SAMAccountName=" + username + ")";
                search.PropertiesToLoad.Add("cn");
                SearchResult result = search.FindOne();
                if(null == result)
                {
                    return false;
                }
                // 更新目录中的用户的新路径
                _path = result.Path;
                _filterAttribute = (String)result.Properties["cn"][0];
            }
            catch (Exception ex)
            {    
            //    throw new Exception("对用户进行身份验证时出错。 " + ex.Message);
                return false;
            }
            return true;
        }
}