Java设计模式 | 七大原则之依赖倒转原则

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依赖倒转原则（Dependence Inversion Principle）

基本介绍

高层模块不应该依赖低层模块，二者都应该依赖其抽象（接口/抽象类）
抽象不应该依赖细节，细节应该依赖抽象
依赖倒转（倒置）的中心思想是面向接口编程
依赖倒转原则是基于这样的设计理念：相对于细节的多变性，抽象的东西要稳定的多。以抽象为基础搭建的架构比以细节为基础搭建的架构要稳定的多。在Java中，抽象指的是接口或抽象类，细节就是具体的实现类
使用接口或抽象类的目的是制定好规范，而不涉及任何具体的操作，把展现细节的任务交给他们的实现类去完成

/*** Created with IntelliJ IDEA.* User: Mingda* Time: 2024/2/26 11:26* File: DependecyInversion* Description: 依赖倒转原则*/
public class DependencyInversion {public static void main(String[] args) {Persion persion = new Persion();persion.receive(new Email());}
}class Email {public String getInfo() {return "email: hello!";}
}/*** 完成Persion接收消息的功能* 方式1:* 1. 简单，容易实现* 2. 如果我们获取的对象是微信，短信等，则需新增类，同时Persion类也需要添加相应的接收方法* 3. 解决思路：引入一个抽象接口IReceive，表示接收者，这样Persion类与接口发生依赖关系。Email、微信、短信等各自实现IReceive接口，符合依赖倒转原则*/
class Persion {public void receive(Email email) {System.out.println(email.getInfo());}
}

/*** Created with IntelliJ IDEA.* User: Mingda* Time: 2024/2/26 11:26* File: DependecyInversion* Description: 依赖倒转原则*/
public class DependencyInversion {public static void main(String[] args) {// 客户端无需改变Persion persion = new Persion();persion.receive(new Email());persion.receive(new WeChat());}
}// 定义一个接口
interface IReceiver {public String getInfo();
}// Email
class Email implements IReceiver {public String getInfo() {return "email: hello!";}
}// 微信
class WeChat implements IReceiver {public String getInfo() {return "wechat: hello!";}
}/*** 方式2*/
class Persion {// 对接口的依赖public void receive(IReceiver receiver) {System.out.println(receiver.getInfo());}
}

依赖关系传递的三种关系

接口传递
构造方法传递
setter方式传递

/*** Created with IntelliJ IDEA.* User: Mingda* Time: 2024/2/26 15:29* File: DependencyPass* Description:*/
public class DependencyPass {public static void main(String[] args) {ChangHong tv = new ChangHong();// 方式1
//        OpenAndClose openAndClose = new OpenAndClose();
//        openAndClose.open(tv);// 方式2
//        OpenAndClose openAndClose = new OpenAndClose(tv);
//        openAndClose.open();// 方式3OpenAndClose openAndClose = new OpenAndClose();openAndClose.setTv(tv);openAndClose.open();}
} 方式1：通过接口传递实现依赖
 开关的接口
//interface IOpenAndClose {
//    public void open(ITV tv);
//}
//
 ITV接口
//interface ITV {
//    public void play();
//}
//
//class ChangHong implements ITV {
//    public void play() {
//        System.out.println("ChangHong is playing");
//    }
//}
//
 实现接口
//class OpenAndClose implements IOpenAndClose {
//    public void open(ITV tv) {
//        tv.play();
//    }
//} 方式2：通过构造方法依赖传递
//interface IOpenAndClose {
//    public void open();
//}
//
//interface ITV {
//    public void play();
//}
//
//class ChangHong implements ITV {
//    public void play() {
//        System.out.println("ChangHong is playing");
//    }
//}
//
//class OpenAndClose implements IOpenAndClose {
//    private ITV tv;
//
//    public OpenAndClose(ITV tv) {
//        this.tv = tv;
//    }
//
//    public void open() {
//        tv.play();
//    }
//}// 方式3：通过setter方法传递
interface IOpenAndClose {public void open();public void setTv(ITV tv);
}interface ITV {public void play();
}class ChangHong implements ITV {public void play() {System.out.println("ChangHong is playing");}
}class OpenAndClose implements IOpenAndClose {private ITV tv;public void setTv(ITV tv) {this.tv = tv;}public void open() {tv.play();}
}