如何获取成员变量的注释? [英] How to get annotations of a member variable?

问题描述

我想知道一个类的一些成员变量的注释，我使用 BeanInfo beanInfo = Introspector.getBeanInfo(User.class) 来内省一个类，并使用 BeanInfo.getPropertyDescriptors() ，查找特定属性，并使用 Class type = propertyDescriptor.getPropertyType() 获取属性的 Class .

I want to know a class's some member variable's annotations , I use BeanInfo beanInfo = Introspector.getBeanInfo(User.class) to introspect a class , and use BeanInfo.getPropertyDescriptors() , to find specific property , and use Class type = propertyDescriptor.getPropertyType() to get the property's Class .

但是不知道怎么把注解加到成员变量上?

But I don't know how to get the annotations added to the member variable ?

我尝试了 type.getAnnotations() 和 type.getDeclaredAnnotations() ，但都返回类的注释，而不是我想要的.例如:

I tried type.getAnnotations() , and type.getDeclaredAnnotations() , but both return the Class's annotations , not what I want . For example :

class User 
{
  @Id
  private Long id;

  @Column(name="ADDRESS_ID")
  private Address address;

  // getters , setters
}

@Entity
@Table(name = "Address")
@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)
class Address 
{
  ...
}

我想获得地址的注释:@Column，而不是类地址的注释(@Entity、@Table、@Cache).如何实现?谢谢.

I want to get the address's annotation : @Column , not class Address's annotations (@Entity , @Table , @Cache) . How to achieve it ? Thanks.

推荐答案

for(Field field : cls.getDeclaredFields()){
  Class type = field.getType();
  String name = field.getName();
  Annotation[] annotations = field.getDeclaredAnnotations();
}

另见:http://docs.oracle.com/javase/tutorial/reflect/class/classMembers.html

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