如何防止缓存中的返回值在spring cacheable中更改 [英] how to prevent a return value from cache to be changed in spring cacheable
问题描述
我正在使用ehcache作为缓存工具来处理spring 3.1注释缓存。
i'm working around spring 3.1 annotation cache with ehcache as a cache implement.
一个像这样返回值的方法
a method with return value like this
@Cacheable("cache")
public MyObject getObj(Object param);
我第一次得到myobject返回值,并且它是可编辑的。
ehcache可以通过设置copyOnRead或copyOnWrite来做些什么。
它会在读/写时强制序列化对象。
但是第一次spring不会从缓存中获取值,它总是按方法本身返回。
i got a myobject return value for the first time,and it's editable. ehcache can do something for that by setting "copyOnRead" or "copyOnWrite". it will force serialize object on read/write. but at the first time spring will not get value from cache,it always return by method itself.
是否有某种方法可以获得只读返回值?
is there some way to get a readonly return value?
推荐答案
您可以编写自己的方面,始终创建返回值的副本,这将使您独立于某些Ehcache设置。
You could write your own aspect that always creates a copy of the returned value, which would make you independent of some Ehcache settings.
首先,像 @CopyReturnValue
这样的标记注释会很好地表达切入点:
At first, a marker annotation like @CopyReturnValue
would be nice for expressing the pointcut:
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface CopyReturnValue {
}
现在,方面可以将此注释用于切入点表达式:
Now, the aspect can use this annotation for the pointcut expression:
@Aspect
@Component
public class CopyReturnValueAspect {
@Around("@annotation(CopyReturnValue)")
public Object doCopyReturnValue(ProceedingJoinPoint pjp) throws Throwable {
Object retVal = pjp.proceed();
Object copy = BeanUtils.cloneBean(retVal); // create a copy in some way
return copy;
}
}
最后,在方法中添加注释:
Finally, add the annotation to your method:
@CopyReturnValue
@Cacheable("cache")
public MyObject getObj(Object param);
对于 CopyReturnValueAspect
我使用 BeanUtils
创建返回值的副本 - 仅作为示例。有关该主题的更多信息,您可能需要查看如何将属性从一个Java bean复制到另一个?
哦,不要忘记在你的Spring配置中启用@AspectJ支持已经:
Oh, don't forget to enable @AspectJ support in you Spring configuration if you haven't already:
<aop:aspectj-autoproxy />
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