9 接口

9.3 完全解耦

Apply

interface Processor {
    String name();
    String process(String input);
};
class Upcase implements Processor {
    @Override
    public String name() {
        return getClass().getSimpleName();
    }
    @Override
    public String process(String input) {
        return input.toLowerCase();
    }
};
class Downcase implements Processor {
    @Override
    public String name() {
        return getClass().getSimpleName();
    }
    @Override
    public String process(String input) {
        return input.toUpperCase();
    }
};
class Apply {
    static void process(Processor processor, String input) {
        System.out.println(processor.process(input));
    }
    public static void chapter9_3() {
        String input = "Hyh";
        process(new Upcase(), input);
        process(new Downcase(), input);
    }
};

策略模式：接口定义公共方法，具体子类定义具体实现。其实就是接口的使用。

9.9 接口与工厂

Factories

interface Service {
    void method();
};
class Implementation1 implements Service {
    @Override
    public void method() {
        System.out.println("Implementation1 Service!");
    }
};
class Implementation2 implements Service {
    @Override
    public void method() {
        System.out.println("Implementation2 Service!");
    }
};
interface ServiceFactory {
    Service getService();
};
class ImplementationFactory1 implements ServiceFactory {
    @Override
    public Service getService() {
        return new Implementation1();
    }
};
class ImplementationFactory2 implements ServiceFactory {
    @Override
    public Service getService() {
        return new Implementation2();
    }
};
class Factories {
    public static void serviceConsumer(ServiceFactory serviceFactory) {
        Service service = serviceFactory.getService();
        service.method();
    }
    public static void chapter9_9() {
        serviceConsumer(new ImplementationFactory1());
        serviceConsumer(new ImplementationFactory2());
    };
};

工厂方法模式：定义一个用于创建对象的接口(ServiceFactory)，让子类(Implementation1Factory)决定实例化哪一个类(new Implementation1())。工厂方法使一个类(ServiceFactory)的实例化延迟到子类(Implementation1Factory)。

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