概述
开放封闭原则是面向对象的设计的中级目标，而依赖倒置原则是实现开放封闭原则的基础。
如果开放封闭原则是设计大楼的蓝田，那么依赖倒置原则就是大楼的钢铁架构。
高层模块（调用者）不应该依赖于低层模块（被调用者），两个都应该依赖于抽象。依赖倒置原则的本质是通过接口或抽象使各个模块的实现独立，彼此互补影响，从而实现模块间的松耦合。.
未使用依赖倒置原则的代码
/// <summary>/// 重复代码很多， Singer作为高层模块，严重依赖底层模块 不符合依赖倒置原则，开放封闭原则 -单一职责原则/// </summary>public class Singer{public void SingSong(ChineseSong chineseSong){Console.WriteLine($"歌手正在唱{chineseSong.GetSongWords()}");}public void SingSongEnglish(EnglishSong englishSong){Console.WriteLine($"歌手正在唱{englishSong.GetSongWords()}");}}public class ChineseSong{public string GetSongWords(){return "中国歌曲";}}public class EnglishSong{public string GetSongWords(){return "外国歌曲";}}
//C#控制台调用Singer singer = new Singer();singer.SingSong(new ChineseSong());singer.SingSongEnglish(new EnglishSong());
结论：重复代码很多， Singer作为高层模块，严重依赖底层模块 不符合依赖倒置原则，开放封闭原则 -单一职责原则。
面向接口编程的代码
public interface ISongWords{public string GetSongWords();}public class ChineseSong2: ISongWords{public string GetSongWords(){return "中国歌曲";}}public class EnglishSong2 : ISongWords{public string GetSongWords(){return "外国歌曲";}}public class Singer2{public void SingSong(ISongWords songWords){Console.WriteLine($"歌手正在唱{songWords.GetSongWords()}");}}
//C#控制台调用Singer2 singer2 = new Singer2();ISongWords songWords = new ChineseSong2();singer2.SingSong(songWords);
依赖倒置原则的代码
抽象不应该依赖细节 细节应该依赖抽象。
public interface ICar{void Run();}public class Benz : ICar{public void Run(){Console.WriteLine("奔驰汽车在本跑");}}public class AoDi : ICar{public void Run(){Console.WriteLine("奥迪汽车在本跑");}}public interface IDriver{//在接口或类中 将要注入的服务对象，以参数的形式直接注入，我们称之为接口注入；void Drive(ICar car);void Drive();void SetCar(ICar car);}public class Student : IDriver{private ICar _car;/// <summary>/// 接口注入/// </summary>/// <param name="car"></param>public void Drive(ICar car){car.Run();}public void Drive(){_car.Run();}/// <summary>/// 属性注入/// </summary>/// <param name="car"></param>public void SetCar(ICar car){_car=car;}}public class Teacher : IDriver{private readonly ICar _car;/// <summary>/// 构造函数注入/// </summary>/// <param name="car"></param>public Teacher(ICar car){_car = car;}public void Drive(ICar car){throw new NotImplementedException();}public void SetCar(ICar car){throw new NotImplementedException();}public void Drive(){_car.Run();}}
//C#控制台调用IDriver driver = new Student();ICar car = new Benz();driver.Drive(car);driver.SetCar(car);driver.Drive();IDriver driver1 = new Teacher(car);driver1.Drive(car);
总结
以上就是关于依赖倒置原则的内容，有何疑问，欢迎与我沟通交流。
