C#设计模式(8)——桥接模式

一、概念

桥接模式即将抽象部分与实现部分脱耦，使它们可以独立变化。

二、模型

三、代码实现 

// 客户端调用
    // 类似Web应用程序
    class Client
    {
        static void Main(string[] args)
        {
            BusinessObject customers = new CustomersBusinessObject("ShangHai");
            customers.Dataacces = new CustomersDataAccess();

            customers.Add("小六");
            Console.WriteLine("增加了一位成员的结果：");
            customers.ShowAll();
            customers.Delete("王五");
            Console.WriteLine("删除了一位成员的结果：");
            customers.ShowAll();
            Console.WriteLine("更新了一位成员的结果：");
            customers.Update("Learning_Hard");
            customers.ShowAll();

            Console.Read();
        }
    }

    // BLL 层
    public class BusinessObject
    {
        // 字段
        private DataAccess dataacess;
        private string city;

        public BusinessObject(string city)
        {
            this.city = city;
        }

        // 属性
        public DataAccess Dataacces
        {
            get { return dataacess; }
            set { dataacess = value; }
        }

        // 方法
        public virtual void Add(string name)
        {
            Dataacces.AddRecord(name);
        }

        public virtual void Delete(string name)
        {
            Dataacces.DeleteRecord(name);
        }

        public virtual void Update(string name)
        {
            Dataacces.UpdateRecord(name);
        }

        public virtual string Get(int index)
        {
            return Dataacces.GetRecord(index);
        }
        public virtual void ShowAll()
        {
            Console.WriteLine();
            Console.WriteLine("{0}的顾客有：", city);
            Dataacces.ShowAllRecords();
        }
    }

    public class CustomersBusinessObject : BusinessObject
    {
        public CustomersBusinessObject(string city) 
            : base(city) { }

        // 重写方法
        public override void ShowAll()
        {
            Console.WriteLine("------------------------");
            base.ShowAll();
            Console.WriteLine("------------------------");
        }
    }

    /// <summary>
    /// 相当于三层架构中数据访问层（DAL）
    /// </summary>
    public abstract class DataAccess
    {
        // 对记录的增删改查操作
        public abstract void AddRecord(string name);
        public abstract void DeleteRecord(string name);
        public abstract void UpdateRecord(string name);
        public abstract string GetRecord(int index);
        public abstract void ShowAllRecords();
    }

    public class CustomersDataAccess:DataAccess
    {
        // 字段
        private List<string> customers =new List<string>();

        public CustomersDataAccess()
        {
            // 实际业务中从数据库中读取数据再填充列表
            customers.Add("Learning Hard");
            customers.Add("张三");
            customers.Add("李四");
            customers.Add("王五");
        }
        // 重写方法
        public override void AddRecord(string name)
        {
            customers.Add(name);
        }

        public override void DeleteRecord(string name)
        {
            customers.Remove(name);
        }

        public override void UpdateRecord(string updatename)
        {
            customers[0] = updatename;
        }

        public override string GetRecord(int index)
        {
            return customers[index];
        }

        public override void ShowAllRecords()
        {
            foreach (string name in customers)
            {
                Console.WriteLine(" " + name);
            }
        }
        
    }