一个简单的自定义注解

1、定义一个自定义注解

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface Token {
    boolean create() default false;
    boolean remove() default false;
}

2、使用注解

public class TokenHandle {
    @Token(create = true, remove = true)
    public void handle(String value) {
        System.out.print("value :" + value);
    }
}

3、利用反射获取注解的值

@Test
    public void testTokenAnnotation() {
        Class tokenClass = TokenHandle.class;
        try {
            Method method = tokenClass.getMethod("handle", String.class);
            Token annotation = method.getAnnotation(Token.class);
            boolean create = annotation.create();
            boolean remove = annotation.remove();
            assertTrue(create);
            assertTrue(remove);
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }
    }

java注解是怎么实现的？