必知必会的设计原则——接口隔离原则

2023-02-10 15:52:10

概述

1、客户端不应该依赖它不需要的接口。
2、一个类对另一个类的依赖应该建立在小接口上。
3、接口应尽量细分，不要在一个接口中放很多方法。

接口分离和单一原则关系

单一职责：只做一件事 /影响类变化的原因只有一个。目的是你为了高内聚（模块内部的相似程度）.
接口隔离：目的是为了低耦合（模块之间的依赖程度要低）。

未使用接口隔离原则的代码

 public interface IScore
    {
        void QueryScore();
        void UpdateScore();
        void AddScore();
        void DeleteScore();
        double GetSumScore();
        double GetAvgScore();
        void PrintScore();
        void SendScore();
    }

    public class Teacher : IScore
    {
        public void AddScore()
        {
            throw new NotImplementedException();
        }
        public void DeleteScore()
        {
            throw new NotImplementedException();
        }
        public double GetAvgScore()
        {
            throw new NotImplementedException();
        }
        public double GetSumScore()
        {
            throw new NotImplementedException();
        }
        public void PrintScore()
        {
            throw new NotImplementedException();
        }
        public void QueryScore()
        {
            throw new NotImplementedException();
        }
        public void SendScore()
        {
            throw new NotImplementedException();
        }
        public void UpdateScore()
        {
            throw new NotImplementedException();
        }
    }
    public class Student : IScore
    {
        public void AddScore()
        {
            throw new NotImplementedException();
        }
        public void DeleteScore()
        {
            throw new NotImplementedException();
        }
        public double GetAvgScore()
        {
            throw new NotImplementedException();
        }
        public double GetSumScore()
        {
            throw new NotImplementedException();
        }
        public void PrintScore()
        {
            throw new NotImplementedException();
        }
        public void QueryScore()
        {
            throw new NotImplementedException();
        }
        public void SendScore()
        {
            throw new NotImplementedException();
        }
        public void UpdateScore()
        {
            throw new NotImplementedException();
        }
    }

以上定义成绩接口，接口里面包含的方法分别为查询成绩，添加成绩、修*改成绩、删除成绩、成就求和，成绩求平均数、打印成绩、发送成绩。Teacher和student类都实现IScore的方法，有些方法教师或学生根本没必要实现。

使用接口隔离原则的代码

 public interface ITeacherScore
    {
        void AddScore();
        void DeleteScore();
        double GetSumScore();
        double GetAvgScore();
        void PrintScore();
        void SendScore();
    }
    public class Teacher2 : ITeacherScore
    {
        public void AddScore()
        {
            throw new NotImplementedException();
        }
        public void DeleteScore()
        {
            throw new NotImplementedException();
        }
        public double GetAvgScore()
        {
            throw new NotImplementedException();
        }

        public double GetSumScore()
        {
            throw new NotImplementedException();
        }

        public void PrintScore()
        {
            throw new NotImplementedException();
        }

        public void SendScore()
        {
            throw new NotImplementedException();
        }
    }

    public interface IStudentScore
    {
        void QueryScore();
        void PrintScore();
    }
    public class Student2 : IStudentScore
    {
        public void PrintScore()
        {
            throw new NotImplementedException();
        }

        public void QueryScore()
        {
            throw new NotImplementedException();
        }
    }