bankoperationsfactory.cs

模拟银行系统的实现

using System;
using System.Collections.Generic;
using System.Text;

namespace Project1
{
    /// <summary>
    /// Create an instance of BankOperations without initializing the class.
    /// </summary>
    public class BankOperationsFactory
    {
        private static BankOperations DB_INSTANCE = createInstance();
        
        /// <summary>
        /// Create an instance of BankOperations
        /// </summary>
        /// <returns>An instance of BankOperations</returns>
        private static BankOperations createInstance()
        {
            try
            {
                BankOperations bankOperations = new BankOperationsImp();
                return bankOperations;
            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
                return null;
            }
        }

        /// <summary>
        /// Get an instance of BankOperations
        /// </summary>
        /// <returns>An instance of BankOperations</returns>
        public static BankOperations getBankOperationsInstance()
        {
            return DB_INSTANCE;
        }

        /// <summary>
        /// Make sure this class cannot be initialized
        /// </summary>
        private BankOperationsFactory()
        {
            // do nothing
        }
    }
}