1、总结

1、忘记注解上该写什么时，可以随意写一个注解然后点击进去参考、复制

2、默认情况下不支持重复注解，需要定义容器

3、标注注解为@Repeatable

4、若需要获取注解的值，可以通过反射获取

2、源码

TestAnnotation

package com.atguigu.java8;

import org.junit.Test;

import java.lang.reflect.Method;

/**

* @author wertherwang

* @create 2019-09-26 15:41

*/

public class TestAnnotation {

@Test

public void test1() throws NoSuchMethodException {

Class clazz = TestAnnotation.class;

Method show = clazz.getMethod("show");

MyAnnotation[] mas = show.getAnnotationsByType(MyAnnotation.class);

for (MyAnnotation myAnnotation : mas) {

System.out.println(myAnnotation.value());

}

}

@MyAnnotation("Hello")

@MyAnnotation("World")

private void show() {

}

}

MyAnnotation

package com.atguigu.java8;

import java.lang.annotation.Repeatable;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.*;

import static java.lang.annotation.ElementType.CONSTRUCTOR;

import static java.lang.annotation.ElementType.LOCAL_VARIABLE;

/**

* @author wertherwang

* @create 2019-09-26 15:35

*/

@Repeatable(MyAnnotations.class)

@Target({TYPE, FIELD, METHOD, PARAMETER, CONSTRUCTOR, LOCAL_VARIABLE})

@Retention(RetentionPolicy.SOURCE)

public @interface MyAnnotation {

String value() default "atguigu";

}

MyAnnotations

package com.atguigu.java8;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.*;

import static java.lang.annotation.ElementType.CONSTRUCTOR;

import static java.lang.annotation.ElementType.LOCAL_VARIABLE;

/**

* @author wertherwang

* @create 2019-09-26 15:39

*/

@Target({TYPE, FIELD, METHOD, PARAMETER, CONSTRUCTOR, LOCAL_VARIABLE})

@Retention(RetentionPolicy.SOURCE)

public @interface MyAnnotations {

MyAnnotation[] value();

}