Java8特性第四讲：Java 8的接口默认方法实现

public interface A {
    default void foo(){
       System.out.println("Calling A.foo()");
    }
}
public class Clazz implements A {
    public static void main(String[] args){
       Clazz clazz = new Clazz();
       clazz.foo();//调用A.foo()
    }
}

public interface List<E> extends Collection<E> {
    default void replaceAll(UnaryOperator<E> operator) {
        Objects.requireNonNull(operator);
        final ListIterator<E> li = this.listIterator();
        while (li.hasNext()) {
            li.set(operator.apply(li.next()));
        }
    }
    default void sort(Comparator<? super E> c) {
        Object[] a = this.toArray();
        Arrays.sort(a, (Comparator) c);
        ListIterator<E> i = this.listIterator();
        for (Object e : a) {
            i.next();
            i.set((E) e);
        }
    }
    default Spliterator<E> spliterator() {
        return Spliterators.spliterator(this, Spliterator.ORDERED);
    }
}

public interface A {
    default String test() {
        return "A";
    }
}
public class B {
    public String test() {
        return "B";
    }
}
public class C extends B implements A {
    public static void main(String[] args) {
        System.out.println(new C().test());
    }
}

public interface D extends A {
    default String test() {
        return "D";
    }
}
public class E implements A, D {
    public static void main(String[] args) {
        System.out.println(new E().test());
    }
}

public class F implements A {
}
public class G extends F implements A, D {
    public static void main(String[] args) {
        System.out.println(new G().test());
    }
}

public interface H {
    default String test() {
        return "H";
    }
}
public class K implements A, H {
    public static void main(String[] args) {
        System.out.println(new K().test());
    }
    @Override
    public String test() {
        return H.super.test();
    }
}

/**
 * 业务检查
 **/
public interface BizChecker extends Checker {
    /**
     * 适用什么阶段
     *
     * @return
     */
    @Override
    @NotNull
    default PhaseEnum phase() {
        return PhaseEnum.BIZ_CHECK;
    }
}

/**
 * 错误码接口
 **/
public interface ErrorCode {
    /**
     * 错误码 必须在{@link ErrorCodeEnum} 中定义
     * @return
     * @see {@link ErrorCodeEnum#getErrCode()}
     */
    String getErrCode();
    /**
     * 错误描述
     * @return
     */
    String getErrDesc();
    /**
     * 是否用在response里对外提示
     * @return
     */
    boolean isFirstTip();
    /**
     * 获取错误字符串：code+desc
     * @return
     */
    default String getErrString() {
        return "code:" + getErrCode() + ",desc:" + getErrDesc() + ",useInResp:" + isFirstTip();
    }
}

/**
 * @Description 限流器
 */
public interface RateLimiter {
    default void acquire() {
        acquire(1);
    }
    /**
     * 限流
     * @param permits 请求资源数
     */
    void acquire(int permits);
}

public interface GoodsFirmHighestPricePretreated {
    /**
     * 处理最高限价针对商品简化
     */
    default Response<Boolean> handleFirmHighestPrice(FullItemDTO fullItemDTO, GoodsPriceContext context) {
        if (CollectionUtils.isEmpty(fullItemDTO.getBaseItem().getSkus())) {
            return Response.ok(true);
        }
    }
}