Configure Caching Declaration

After configuring your Spring application and enabling caching, the next step is to identify the methods that need to be cached and their respective policies.

You can bind the caching behaviors to the methods using:

Caching Annotations
Declarative XML-based Caching

Configure Using Caching Annotations

For caching declarations, the abstraction provides Java annotations that allow methods to trigger cache population or cache eviction.

Example

Let’s consider a web service with two classes that explain how caching takes place using the @Cacheable annotation.

// BookController.java
@RestController
@RequestMapping("/books")
public class BookController {
    @Autowired
    // Get a Spring Service to save objects in the DB. This also caches them with 5min absolute (TTL) expiration.
    BookService service = context.getBean(BookService.class);
    service.save(new Book(18001, "The Second Machine Age", "Erik Brynjolfsson, Andrew McAfee", new Date(2014, 0, 20)));

    // Print all saved books details
    printBooks(service.listAll());

    // Use Spring Service to get a book from the DB. It actually comes from the cache
    Book foundBook = service.findBookByIsbn(18001);
    printBookDetails(foundBook);

    foundBook.setAuthor("New Author");
    Book UpdatedBook = service.update(foundBook);

    printBookDetails(UpdatedBook);
    context.close();
    System.exit(0);
    }

// BookService.java
@Service
class BookService {
    @Autowired
    private BookRepository repo;

    public List<Book> listAll() {
        return repo.findAll();
    }

    @CachePut(value = "demoCache", key = "#book.getISBN()")
    public Book save(Book book) { return repo.save(book); }

    @CachePut(value = "demoCache", key = "#book.getISBN()")
    public Book update(Book book) { return repo.save(book); }

    @Cacheable(value = "demoCache", key = "#id")
    public Book get(int id) {
        return repo.findById(id);
    }

    @Cacheable(value = "demoCache", key = "#isbn")
    public Book findBookByIsbn(long isbn) {
        return repo.findBookByIsbn(isbn);
    }

    @CacheEvict(value = "demoCache", allEntries = true)
    public void delete(int id) {
        repo.deleteById(id);
    }
}

To get a detailed understanding and to learn more about other Caching Annotations or the creation of the Custom Key Generator, refer to the Spring Documentation.

Configure using Declarative XML-based Caching

If annotations are not an option, i.e., if you have limited access to the sources or no external code, you can use XML for declarative caching. Here, you can specify the target method and the caching directives externally.

In the configuration below, the bookService is made cacheable. The caching semantics are encapsulated in the cache:advice definition, which instructs the method getBookNameByIsbn to put data into the cache while the loadBooks method evicts data. Both definitions are working against the demoCache.

Note

When using the class tag please make sure you use the fully qualified name of your class.

<!-- the service we want to make cacheable -->
<bean id="bookService" class="x.y.service.BookService"/>

<!-- cache definitions -->
<cache:advice id="booksCacheAdvice" cache-manager="cacheManager">
    <cache:caching cache="demoCache">
        <cache:cacheable method="getBookNameByIsbn" key="#isbn"/>
        <cache:cache-evict method="loadBooks" all-entries="true"/>
    </cache:caching>
</cache:advice>

Also, for using the Custom Key Generator for cache key generation through XML-based caching, beans created for the key generator need to be defined as shown below in CustomerKeyGenerator as a class.

<bean id="customerKeyGenerator" class="cachekeygenerator.CustomerKeyGenerator">

Here, the customerKeyGenerator generates a cache key whenever a customer is added to the customersCache. To use this generator, you must specify the keygenerator bean in your cache:advice tag.

<cache:advice id="customerCacheAdvice" key-generator="customerKeyGenerator">
    <cache:caching cache="customersCache">
        <cache:cacheable method="findCustomerByID"/>
    </cache:caching>
</cache:advice>

After modifying all these configurations, your application is now ready to use NCache as a Spring Caching Provider.

Configure Caching Declaration

Configure Using Caching Annotations

Example

Configure using Declarative XML-based Caching

Note

See Also