类级别的注解VS接口 [英] class level annotations vs interfaces
问题描述
我在看一些code,其中的类级别的注解是用来添加属性某些类,以后使用反射这些属性来访问和使用。
I am looking at some code where class level annotations are used to 'add' properties to certain classes, later using reflection these properties are accessed and used.
我的问题:
什么时候适合使用一个注解新字段添加,而不是使用一个接口的类。有哪些优点和缺点呢?
My question: When is it appropriate to use an annotation to add new fields to a class, instead of using an interface. What are some benefits and drawbacks to this?
推荐答案
我不知道注释将永远取代的接口,但我有种看到诱惑力。这一切都取决于实现方式虽然。
I don't know that annotations would ever replace an interface, but I can kind of see the allure. It all depends on the implementations though.
注解提供元数据来进一步描述code,其中,消费者(大部分时间)间$ P $点在运行时使用反射。使用一个接口,实现本合同明确规定。
Annotations provide meta data to further describe code, which a consumer (most of the time) interprets at runtime using reflections. Using an interface, this contract of implementation is clearly defined.
您可以有:
interface CrudDao<T> {
Serializable create(T t);
T read(Serializable id);
void update(T t);
void delete(T t);
}
这将是实现一个繁琐的合同,可能会产生某种方法链的。
This would be a cumbersome contract to implement, and would likely incur some sort of method chaining.
相反,你可以这样做:
class SomeDao {
@Create
long create(SomeEntity e) { // code }
@Read
SomeEntity read(long id) { // code }
@Update
void update(SomeEntity e) { // code }
@Delete
void delete(SomeEntity e) { // code }
}
的缺点是,这将是很麻烦的使用方法:
The drawback is that it would be cumbersome to use:
class CrudFactory {
long create(Class clazz, Object obj) {
// loop through methods
// find method with @Create
// call method
}
}
在本例中注解将是一个矫枉过正的大部分时间,海事组织。也有一些是必须说,大约一个明确的,有据可查的合同。
Annotations in this example would be overkill a majority of the time, IMO. There is something to be said about a clearly defined, well documented contract.
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