Spring caching works only sometimes

Question

I have a Spring controller and want to cache the response. When I move the @Cacheable annotation from the getBooks to the doGetBooks method, the caching will stop. Once I move it back to the getBooks method caching works again. Why is that and how can I fix it?

This will cache the public method response

@GetMapping
@Cacheable(value = "cache", key = "{ #root.methodName }")
public Books getBooks(@RequestHeader(value = "user-agent", required = false) String userAgent) throws Exception {
     if(valid) {
          return this.doGetBooks();
     }
     throw new Exception();
}


public Books doGetBooks() throws Exception{
    ...

This will never cache the private method response

@GetMapping
public Books getBooks(@RequestHeader(value = "user-agent", required = false) String userAgent) throws Exception {
     if(valid) {
          return this.getBooks();
     }
     throw new Exception();
}


@Cacheable(value = "cache", key = "{ #root.methodName }")
public Books doGetBooks() throws Exception{
    ...

Answer 1

Problem: You are calling doGetBooks() within the same class, and Spring cache requires an AOP proxy to the called method.

This is a good discussion describing why Spring AOP can not intercept methods called by other class methods: AOP calling methods within methods

There are at least three workarounds:

1. Refactor the code: Move doGetBooks() into another @Component, and invoke the method using that (injected) bean (refactoredBean.doGetBooks())
2. Create a self-reference to the service invoking the call (By @Autowired private MyService myservice and invoke myservice.doGetBooks().
3. Using the ApplicationContext to cast the service bean, and invoking the method on that bean.

Once you invoke a method that Spring Cache can intercept (via AOP), then the @Cacheable() annotation should trigger.