Spring Boot根据请求禁用@Cacheable

Question

I'm trying to disable a Cacheable function in Spring Boot based on a URL parameter. For example http://myapplication.com/some/request?cache=false

I tried the condition with SpEL but I haven't been able to get it work

@Cacheable(value = "value", keyGenerator = "keygenerator", condition = "#{someComponent.isCacheEnabled()}")

Any suggestions? Thanks in advance!

Answer 1

user4843-

I am assuming your "arbitrary component" (ie someComponent ) is a Spring managed bean in your Spring ApplicationContext ?

If so, then you have not properly referenced this Spring managed bean using the SpEL expression specified on the condition attribute inside your @Cacheable annotation declaration. It should read...

condition="#{@someComponent.isCacheEnabled()}"

Notice the use of the @ symbol on someComponent , which is explained in more detail here . And, although the Spring documentation is less than clear on the matter, it does imply the SpEL evaluation context created and used inside Spring's Cache Abstraction when processing the caching annotations uses "the built-in parameters", or SpEL conventions , in addition to the ones listed in Table 36.1 - Cache SpEL available metadata . See examples here .

I would also caution you on your use of some arbitrary component, or Spring managed bean to manage caching state for your entire application like this.

1. First, if someComponent is a Singleton bean (the default in the Spring container) then this bean would need to be Thread-safe, particularly as its state is changing, possibly and seemingly with every HTTP request, which leads me to...

2. I am not sure you want a Spring managed bean managing the "cacheable state" of your application service/repository methods if the caching state is conditional on each and every individual HTTP request, particularly since most HTTP containers process each HTTP request in a separate Thread. You are most certainly going to run into race conditions. In this case, I'd rather use an additional cacheable service method parameter to determine the cacheable state of that particular service method invocation, stemming from the HTTP request.

Example:

@Cacheable(value = "value", keyGenerator="keyGenerator" conditional="#enableCaching")
public <return-type> someCacheableServiceMethod(..., boolean enableCaching) {
  ...
}

In fact, I'd even suggest using more intelligible business-oriented rules to determine the cacheable state of your service methods.

Hope this helps!

-John