设计模式——接口隔离原则

接口隔离原则（Interface Segregation Principle）

基本介绍

客户端不应该依赖它不需要的接口，即一个类对另一个类的依赖应该建立在最小的接口上

类A通过接口Interface1依赖类B，类C通过接口Interface1依赖（使用）类B，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

dart 复制代码

package com.baidu.principle.segregation;
public class SegregationDemo1 {
    public static void main(String[] args) {
        A a = new A();
        Interface1 i1 = new B();
        a.depend1(i1);
        a.depend2(i1);
        a.depend3(i1);

        C c = new C();
        Interface1 i2 = new D();
        c.depend1(i2);
        c.depend4(i2);
        c.depend5(i2);


    }
}
interface Interface1 {
    void operation1();

    void operation2();

    void operation3();

    void operation4();

    void operation5();
}

class B implements Interface1 {

    @Override
    public void operation1() {
        System.out.println("B实现了操作1");

    }

    @Override
    public void operation2() {
        System.out.println("B实现了操作2");

    }

    @Override
    public void operation3() {
        System.out.println("B实现了操作3");

    }

    @Override
    public void operation4() {
        System.out.println("B实现了操作4");

    }

    @Override
    public void operation5() {
        System.out.println("B实现了操作5");

    }
}


class D implements Interface1 {

    @Override
    public void operation1() {
        System.out.println("D实现了操作1");

    }

    @Override
    public void operation2() {
        System.out.println("D实现了操作2");

    }

    @Override
    public void operation3() {
        System.out.println("D实现了操作3");

    }

    @Override
    public void operation4() {
        System.out.println("D实现了操作4");

    }

    @Override
    public void operation5() {
        System.out.println("D实现了操作5");

    }
}


class A {

//    A 类通过接口Interface1 依赖使用B，但是只会用到1,2,3方法

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

    public void depend2(Interface1 i) {
        i.operation2();
    }

    public void depend3(Interface1 i) {
        i.operation3();
    }
}

class C {

    //    C 类通过接口Interface1 依赖使用D，但是只会用到1,4,5方法

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

    public void depend4(Interface1 i) {
        i.operation4();
    }

    public void depend5(Interface1 i) {
        i.operation5();
    }


}

解决：

将接口Interface1拆分为独立的几个接口，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

dart 复制代码

package com.baidu.principle.segregation.improve;
public class SegregationDemo1 {

    public static void main(String[] args) {
      

    }
}

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() {
    }

    @Override
    public void operation2() {
    }

    @Override
    public void operation3() {
    }
}

class D implements Interface1, Interface3 {

    @Override
    public void operation1() {
    }

    @Override
    public void operation4() {
    }

    @Override
    public void operation5() {
    }
}



class A {

//    A 类通过接口Interface1 依赖使用B，但是只会用到1,2,3方法

    public void depend1(Interface1 interface1) {
        interface1.operation1();
    }

    public void depend2(Interface2 interface2) {
        interface2.operation2();
    }

    public void depend3(Interface2 interface2) {
        interface2.operation3();
    }
}

class C {

    //    C 类通过接口Interface1 依赖使用D，但是只会用到1,4,5方法

    public void depend1(Interface1 interface1) {
        interface1.operation1();
    }

    public void depend4(Interface3 interface3) {
        interface3.operation4();
    }

    public void depend5(Interface3 interface3) {
        interface3.operation5();
    }


}