设计模式七大原则之接口隔离原则

Posted 2020-12-14 clownadam

接口隔离原则

　　客户端不应该被迫依赖于他不使用的方法。即一个类对另一个类的依赖应该建立在最小的接口上。要为各个类建立它们需要的专用接口，而不要试图去建立一个庞大的接口供所有依赖它的类去调用。

类A通过接口Interface1依赖类B，类C通过接口Interface1依赖类D，如果接口Interface1对于类A和类C来说不是最小接口，那么类B和类D必须去实现他们不需要的方法。

interface Interface1 {
    void operation1();

    void operation2();

    void operation3();

    void operation4();

    void operation5();
}

class B implements Interface1 {

    @Override
    public void operation1() {
        System.out.println("B实现了operation1");
    }

    @Override
    public void operation2() {
        System.out.println("B实现了operation2");
    }

    @Override
    public void operation3() {
        System.out.println("B实现了operation3");
    }

    @Override
    public void operation4() {
        System.out.println("B实现了operation4");
    }

    @Override
    public void operation5() {
        System.out.println("B实现了operation5");
    }
}

class D implements Interface1 {

    @Override
    public void operation1() {
        System.out.println("D实现了operation1");
    }

    @Override
    public void operation2() {
        System.out.println("D实现了operation2");
    }

    @Override
    public void operation3() {
        System.out.println("D实现了operation3");
    }

    @Override
    public void operation4() {
        System.out.println("D实现了operation4");
    }

    @Override
    public void operation5() {
        System.out.println("D实现了operation5");
    }
}
class A{
    public void depend1(Interface1 i){
        i.operation1();
    }
    public void depend2(Interface1 i){
        i.operation2();
    }
    public void depend3(Interface1 i){
        i.operation3();
    }
}
class C{
    public void depend1(Interface1 i){
        i.operation1();
    }
    public void depend4(Interface1 i){
        i.operation4();
    }
    public void depend5(Interface1 i){
        i.operation5();
    }
}

按接口隔离原则应当这样处理：

　　将接口Interface1拆分为独立的几个接口(此处拆分为三个接口)，类A和类C分别与他们需要的接口建立依赖关系，也就是采用接口隔离原则

public class InterfaceSegregation1 {
    public static void main(String[] args) {
        A a = new A();
        a.depend1(new B());
        a.depend2(new B());
        a.depend3(new B());

        C c = new C();
        c.depend1(new D());
        c.depend4(new D());
        c.depend5(new D());
    }
}

interface Interface1 {
    void operation1();
}

interface Interface2 {
    void operation2();
    void operation3();
}

interface Interface3 {
    void operation4();
    void operation5();
}

class B implements Interface1,Interface2 {

    @Override
    public void operation1() {
        System.out.println("B实现了operation1");
    }

    @Override
    public void operation2() {
        System.out.println("B实现了operation2");
    }

    @Override
    public void operation3() {
        System.out.println("B实现了operation3");
    }

}

class D implements Interface1,Interface3 {

    @Override
    public void operation1() {
        System.out.println("D实现了operation1");
    }

    @Override
    public void operation4() {
        System.out.println("D实现了operation4");
    }

    @Override
    public void operation5() {
        System.out.println("D实现了operation5");
    }
}

class A {
    public void depend1(Interface1 i) {
        i.operation1();
    }

    public void depend2(Interface2 i) {
        i.operation2();
    }

    public void depend3(Interface2 i) {
        i.operation3();
    }
}

class C {
    public void depend1(Interface1 i) {
        i.operation1();
    }

    public void depend4(Interface3 i) {
        i.operation4();
    }

    public void depend5(Interface3 i) {
        i.operation5();
    }
}

接口隔离原则和单一职责原则都是为了提高类的内聚性、降低它们之间的耦合性，体现了封装的思想，但两者是不同的：

　　1、单一职责原则注重的是职责，而接口隔离原则注重的是对接口依赖的隔离；

　　2、单一职责原则主要约束的是类，他针对的是程序的实现和细节；接口隔离原则主要约束接口，主要针对抽象和程序整体框架的构建。