外观模式

1.外观模式类

namespace Data
{
    /*外观模式：为外界调用提供一个统一的接口，把其他类中需要用到的方法提取
     * 出来，由外观类进行调用。然后在调用段实例化外观类，以间接调用需要的
     * 方法。这种方式和代理模式有异曲同工之妙。然而，根据迪米特法则，代理
     * 模式应该尽可能的为单个对象进行代理。而外观模式更像是从众多类中提取
     * 有用的方法而组合成的新类*/
    public class Facde
    {
        private string result;
        InsertDB insert;
        UpdateDB update;
        DelDB del;
        public Facde()
        {
            insert = new InsertDB();
            update = new UpdateDB();
            del = new DelDB();
        }

        public string OperateDB()
        {
            result = insert.OperateData() + "\n" + update.OperateData() + "\n" + del.OperateData();
            return result;
        }
    }

    /// <summary>
    /// 添加数据类
    /// </summary>
    public class InsertDB
    {
        public string OperateData()
        {
            NorthwindEntities db = new NorthwindEntities();
            Employees e = new Employees();
            e.LastName = "yoyozhu";
            e.FirstName = "zhushao";
            db.AddToEmployees(e);
            db.SaveChanges();
            return "添加数据成功";
        }
    }

    /// <summary>
    /// 删除数据类
    /// </summary>
    public class DelDB
    {
        public string OperateData()
        {
            NorthwindEntities db = new NorthwindEntities();
            Employees e = db.Employees.Where(c => c.EmployeeID == 44).FirstOrDefault();
            db.DeleteObject(e);
            db.SaveChanges();
            return "删除数据成功";
        }
    }

    /// <summary>
    /// 修改数据类
    /// </summary>
    public class UpdateDB
    {
        public string OperateData()
        {
            NorthwindEntities db = new NorthwindEntities();
            Employees e = db.Employees.Where(c => c.EmployeeID == 44).FirstOrDefault();
            e.LastName = "chuanshi_yoyo";
            db.SaveChanges();
            return "修改数据成功";
        }
    }
}

2.调用

      static void Main(string[] args)
        {
            Facde f = new Facde();
            Console.WriteLine(f.OperateDB());
            Console.ReadKey();
        }