Java 匿名类

工厂方法

匿名类与正规的继承相比有些受限，因为匿名类既可以扩展类，也可以实现接口，但不能两者兼备。如果实现接口，也就只能实现一个接口。

package innerclasses;


interface Service{
    void method1();
    void method2();
}

interface ServiceFactory{
    Service getService();
}

class Implementation1 implements Service{
    private Implementation1(){}
    public void method1(){
        System.out.println("Implemention1 method1");
    }
    public void method2(){
        System.out.println("Implemention1 method1");
    }
    //下面是匿名类
    public static ServiceFactory factory = new ServiceFactory(){
        public Service getService(){
            return new Implementation1();
        }
    };
}

class Implementation2 implements Service{
    private Implementation2(){}
    public void method1(){
        System.out.println("Implemention2 method1");
    }
    public void method2(){
        System.out.println("Implemention2 method2");
    }
    
    public static ServiceFactory factory = new ServiceFactory(){
        public Service getService(){
            return new Implementation2();
        }
    };
}

public class Factories{
    public static void serviceConsumer(ServiceFactory fact){
        Service s = fact.getService();
        s.method1();
        s.method2();
    }
    public static void main(String [] args){
        serviceConsumer(Implementation1.factory);
        serviceConsumer(Implementation2.factory);
    }
}

结果：

Implemention1 method1
Implemention1 method1
Implemention2 method1
Implemention2 method2