/// <summary>
 /// 抽象工厂类
 /// </summary>
 public interface IDatabaseFactory
 {

  IEmployee CreateEmployee();

  IUser CreateUser();
 }

 /// <summary>
 /// 与SqlServer相关产品的实现
 /// </summary>
 public class SqlServerDatabaseFactory : IDatabaseFactory
 {

  public IEmployee CreateEmployee()
  {

   return new SqlEmployee();
  }

  public IUser CreateUser()
  {

   return new SqlUser();
  }

 }


 /// <summary>
 /// 与Access相关产品的实现
 /// </summary>
 public class AccessDatabaseFactory : IDatabaseFactory
 {

  public IEmployee CreateEmployee()
  {

   return new AccessEmployee();
  }

  public IUser CreateUser()
  {

   return new AccessUser();
  }

 }

 /// <summary>
 /// 抽象产品
 /// </summary>
 public interface IUser 
 {
  User GetUser();

  bool SaveUser();
 }

 /// <summary>
 /// 抽象产品
 /// </summary>
 public interface IEmployee
 {

  Employee GetEmployee();

  bool SaveEmployee();
 }

 /// <summary>
 /// 与SqlServer相关的具体产品User
 /// </summary>
 public class SqlUser : IUser
 {
  public User GetUser()
  {

   return null;
  }

  public bool SaveUser()
  {

   return false;
  }

 }

 /// <summary>
 /// 与SqlServer相关的具体产品Employee
 /// </summary>
 public class SqlEmployee : IEmployee
 {

  public SqlEmployee()
  {

  }

  public Employee GetEmployee()
  {

   return null;
  }

  public bool SaveEmployee()
  {

   return false;
  }

 }

 /// <summary>
 /// 与Access相关的具体产品User
 /// </summary>
 public class AccessUser : IUser
 {

  public AccessUser()
  {

  }

  public User GetUser()
  {

   return null;
  }

  public bool SaveUser()
  {

   return false;
  }

 }

 /// <summary>
 /// 与Access相关的具体产品Employee
 /// </summary>
 public class AccessEmployee : IEmployee
 {

  public AccessEmployee()
  {

  }

  public Employee GetEmployee()
  {

   return null;
  }

  public bool SaveEmployee()
  {

   return false;
  }

 }