Java8接口默认静态方法及重复注解原理解析

interface MyInterface1 {

	default String method1() {
		return "myInterface1 default method";
	}
}

class MyClass{
	public String method1() {
		return "myClass method";
	}
}

/**
 * 父类和接口中都有相同的方法，默认使用父类的方法，即类优先
 * @author 莫雨朵
 *
 */
class MySubClass1 extends MyClass implements MyInterface1{

}

@Test
public void test1() {
 MySubClass1 mySubClass1=new MySubClass1();
 System.out.println(mySubClass1.method1());//myClass method
}

interface MyInterface1 {

	default String method1() {
		return "myInterface1 default method";
	}
}

interface MyInterface2 {

	default String method1() {
		return "myInterface2 default method";
	}
}

/**
 * 如果类实现的接口中有名字相同参数类型一致的默认方法，那么在类中必须重写
 * @author 莫雨朵
 *
 */
class MySubClass2 implements MyInterface1,MyInterface2{

	@Override
	public String method1() {
		return MyInterface1.super.method1();
	}
	
}

@Test
public void test2() {
 MySubClass2 mySubClass2=new MySubClass2();
 System.out.println(mySubClass2.method1());//myInterface1 default method
}

interface MyInterface1 {	
	static String method2() {
		return "interface static method";
	}
}

@Test
public void test3() {
 System.out.println(MyInterface1.method2());//interface static method
}

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface MAnnotation {
	String name() default "";
	int age();
}

public class AnnotataionTest {

	@Test
	public void test() throws Exception {
		Class<AnnotataionTest> clazz=AnnotataionTest.class;
		Method method = clazz.getMethod("good", null);
		MAnnotation annotation = method.getAnnotation(MAnnotation.class);
		System.out.println(annotation.name()+":"+annotation.age());
	}
	
	@MAnnotation(name="tom",age=20)
	public void good() {
		
	}
}

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
@Repeatable(MAnnotations.class)//使用@Repeatable来标注存储注解的注解
public @interface MAnnotation {
	String name() default "";
	int age();
}

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface MAnnotations {
	MAnnotation[] value();
}

public class AnnotataionTest {

	@Test
	public void test() throws Exception {
		Class<AnnotataionTest> clazz=AnnotataionTest.class;
		Method method = clazz.getMethod("good");
		MAnnotation[] mAnnotations = method.getAnnotationsByType(MAnnotation.class);
		for (MAnnotation annotation : mAnnotations) {
			System.out.println(annotation.name()+":"+annotation.age());
		}
	}
	
	@MAnnotation(name="tom",age=20)
	@MAnnotation(name="jack",age=25)
	public void good() {
		
	}
}