{C#}设计模式辨析.代理

背景

• 在原程序上加壳，ex. 壳=虚拟/保护/远程/日志记录 等

示例

using static System.Console;

namespace DesignPattern_Proxy
{
    // 真实类接口，可与代理类互换
    public interface ILogin
    {
        void Perform(string name);
    }

    // 真实类
    public class RealLogin : ILogin
    {
        public void Perform(string name)
            => WriteLine($"{name} is logged in.");
    }

    // 代理类
    public class LoginProxy : ILogin
    {
        private readonly ILogin login;
        private readonly string password;

        // 传入真实类
        public LoginProxy(ILogin login, string password)
        {
            this.login = login;
            this.password = password;
        }

        public void Perform(string name)
        {
            // 加壳
            if (!IsRightPassword(password))
            {
                WriteLine($"Invalid password of {name}!");
                return;
            }

            login.Perform(name);
        }

        private bool IsRightPassword(string password)
            => password == "123456";
    }

    class Program
    {
        static void Main(string[] args)
        {
            var real = new RealLogin();
            var proxy = new LoginProxy(real, "012345");
            proxy.Perform("Zhang San");

            proxy = new LoginProxy(real, "123456");
            proxy.Perform("Zhang San");

            ReadKey();
        }
    }
}