以下是高人(动软卓越)的代码   
//验证登录信息，如果验证通过则返回当前用户对象的安全上下文信息
  AccountsPrincipal newUser = AccountsPrincipal.ValidateLogin(userName, Password);
  if (newUser == null)//登录信息不对
  {
  this.lblMsg.Text = "登陆失败： " + userName;
  if ((Session["PassErrorCountAdmin"] != null) && (Session["PassErrorCountAdmin"].ToString() != ""))
  {
  int PassErroeCount = Convert.ToInt32(Session["PassErrorCountAdmin"]);
  Session["PassErrorCountAdmin"] = PassErroeCount + 1;
  }
  else
  {
  Session["PassErrorCountAdmin"] = 1;
  }
  }
---------------------------------------------------------------------

然后我查看AccountsPrincipal.ValidateLogin的定义,如下
 public class AccountsPrincipal : IPrincipal
  {
  protected IIdentity identity;
  protected ArrayList permissionList;
  protected ArrayList permissionListid;
  protected ArrayList roleList;

  public AccountsPrincipal(int userID);
  public AccountsPrincipal(string userName);

  public IIdentity Identity { get; set; }
  public ArrayList Permissions { get; }
  public ArrayList PermissionsID { get; }
  public ArrayList Roles { get; }

  public static byte[] EncryptPassword(string password);
  public bool HasPermission(string permission);
  public bool HasPermissionID(int permissionid);
  public bool IsInRole(string role);
  public static AccountsPrincipal ValidateLogin(string userName, string password);
  }


我的第一个疑问是 为什么public static AccountsPrincipal ValidateLogin(string userName, string password);下面不在用大括号{}了呢, 光突突的好难看.语法感觉怪怪的.
第二点,我觉得AccountsPrincipal 是继承 IPrincipal ,我查看了一下IPrincipal的类,结果如下
 public interface IPrincipal
  {
  // 摘要:
  // Gets the identity of the current principal.
  //
  // 返回结果:
  // The System.Security.Principal.IIdentity object associated with the current
  // principal.
  IIdentity Identity { get; }

  // 摘要:
  // Determines whether the current principal belongs to the specified role.
  //
  // 参数:
  // role:
  // The name of the role for which to check membership.
  //
  // 返回结果:
  // true if the current principal is a member of the specified role; otherwise,
  // false.
  bool IsInRole(string role);
  }
好简单哦,但是如何成就验证用户名和密码正确,还是一个迷

AccountsPrincipal ValidateLogin这个更像一个委托
还有就是C#里是允许先声名函数，然后在类外部实现函数的。