【C#语言入门】22. 接口、依赖反转、单元测试

news2025/2/22 3:41:07

【C#语言入门】22. 接口、依赖反转、单元测试

一、接口与单元测试

接口的产生：自底向上（重构），自顶向下（设计）
C#中接口的实现（隐式，显式，多接口）
语言对面向对象设计的内建支持：依赖反转，接口隔离，开/闭原则……

在这里插入图片描述

//不使用接口，会很麻烦
class Program
{
    static void Main(string[] args)
    {
        int[] nums1 = new int[] { 1, 2, 3, 4, 5 };
        ArrayList nums2 = new ArrayList() { 1, 2, 3, 4, 5};
        Console.WriteLine(Sum(num1));
        Console.WriteLine(Avg(num1));
        Console.WriteLine(Sum(num2));
        Console.WriteLine(Avg(num2));
    }

    static int Sum(int[] nums)
    {
        int sum = 0;
        foreach (int x in nums) {
        sum += x;}
        return sum;
    }

    static double Avg(int[] nums)
    {
        int sum = 0;
        double count = 0;
        foreach(int x in nums)
        {
            sum += x;
            count++;
        }
        return sum/count;
    }

    static int Sum(ArrayList nums)
    {
        int sum = 0;
        foreach(var x in nums)
        {
            sum += (int)x;
        }
        return sum;
    }

    static double Avg(ArrayList nums)
    {
        int sum = 0;
        double count = 0;
        foreach(var x in nums)
        {
            sum += (int)x;
            count++;
        }
        return sum/count;
    }
}

//使用了IEnumerable接口
class Program
{
    static void Main(string[] args)
    {
        int[] nums1 = new int[] { 1, 2, 3, 4, 5 };
        ArrayList nums2 = new ArrayList() { 1, 2, 3, 4, 5};

        Console.WriteLine(Sum(nums1));
        Console.WriteLine(Avg(nums1));
        Console.WriteLine(Sum(nums2));
        Console.WriteLine(Avg(nums2));
    }

    static int Sum(IEnumerable nums)
    {
        int sum = 0;
        foreach (int x in nums) {
        sum += x;}
        return sum;
    }

    static double Avg(IEnumerable nums)
    {
        int sum = 0;
        double count = 0;
        foreach(int x in nums)
        {
            sum += x;
            count++;
        }
        return sum/count;
    }

}

二、依赖

在现实世界中，由于自身能力有限，合作是一个非常常见的行为，而面向对象是对现实世界的抽象，因此也存在着类与类、对象与对象的合作，即”依赖“。依赖的出现伴随着耦合，依赖越直接，耦合度越高。

class Program
{
    static void Main(string[] args)
    {
        var user = new PhoneUser(new NokiaPhone());
        //var user = new PhoneUser(new EricssonPhone());超级无敌松耦合，只要改这里就能实现手机切换
        user.UsePhone();
    }

}

class PhoneUser
{
    private IPhone _phone;
    public PhoneUser(IPhone phone)
    {
        _phone = phone;
    }

    public void UsePhone()
    {
        _phone.Dail();
        _phone.PickUp();
        _phone.Send();
        _phone.Receive();
    }
}

interface IPhone
{
    void Dail();
    void PickUp();
    void Send();
    void Receive();
}

class NokiaPhone:IPhone
{
    public void Dail()
    {
        Console.WriteLine("Nokia calling...");
    }

    public void PickUp()
    {
        Console.WriteLine("Hello!This is Tom");
    }

    public void Receive()
    {
        Console.WriteLine("Nokia message ring...");
    }

    public void Send()
    {
        Console.WriteLine("Hello!");
    }
}

class EricssonPhone : IPhone
{
    public void Dail()
    {
        Console.WriteLine("Ericsson calling...");
    }

    public void PickUp()
    {
        Console.WriteLine("Hello!This is Tom");
    }

    public void Receive()
    {
        Console.WriteLine("Ericsson message ring...");
    }

    public void Send()
    {
        Console.WriteLine("Hello!");
    }
}