Hello world

 Hello world

SPRING CACHE :

1.       Dependency :

Contains core cache implementation

<dependency>

    <groupId>org.springframework</groupId>

    <artifactId>spring-context</artifactId>

    <version>5.1.8.RELEASE</version>

</dependency>

Provides more cache managers like EHCache, etc.

<dependency>

    <groupId>org.springframework</groupId>

    <artifactId>spring-context-support</artifactId>

    <version>5.1.8.RELEASE</version>

</dependency>

For spring boot

<dependency>

    <groupId>org.springframework.boot</groupId>

    <artifactId>spring-boot-starter-cache</artifactId>

</dependency>

@EnableCaching

@Configuration

@EnableCaching

public class CachingConfig {

    @Bean

    public CacheManager cacheManager() {

        return new ConcurrentMapCacheManager("addresses");

    }

}

XML based caching

<beans>

    <cache:annotation-driven />

    <bean id="cacheManager" class="org.springframework.cache.support.SimpleCacheManager">

        <property name="caches">

            <set>

                <bean

                  class="org.springframework.cache.concurrent.ConcurrentMapCacheFactoryBean"

                  name="addresses"/>

            </set>

        </property>

    </bean>

</beans>

2.       Spring boot – By default ConcurrentMapCacheManager is registered.

3.       Customization :

@Component

public class SimpleCacheCustomizer

  implements CacheManagerCustomizer<ConcurrentMapCacheManager> {

    @Override

    public void customize(ConcurrentMapCacheManager cacheManager) {

        cacheManager.setCacheNames(asList("users", "transactions"));

    }

}

4.       Single cache :

5.       @Cacheable("addresses")

public String getAddress(Customer customer) {...}

Call is optional. First checks in “addresses” cache. If not present, then method is called and result is put into cache.

6.       Multiple cache :

Call is optional. First checks in “addresses” and “directory” caches. If not present, then method is called and result is put into cache.

@Cacheable({"addresses", "directory"})

public String getAddress(Customer customer) {...}

7.       Clears all entries in cache “addresses”.

@CacheEvict(value="addresses", allEntries=true)

public String getAddress(Customer customer) {...}

8.       Method is always executed. Results are updated in cache

@CachePut(value="addresses")

public String getAddress(Customer customer) {...}

9.       Using multiple annotations :

@Caching(evict = {

  @CacheEvict("addresses"),

  @CacheEvict(value="directory", key="#customer.name") })

public String getAddress(Customer customer) {...}

10.   Class-level annotation :

Will be applied to all methods in the class.

@CacheConfig(cacheNames={"addresses"})

public class CustomerDataService {

    @Cacheable

    public String getAddress(Customer customer) {...}

11.   Conditional cache :

Caching will be done if customer’s name is Tom (argument)

@CachePut(value="addresses", condition="#customer.name=='Tom'")

public String getAddress(Customer customer) {...}

12.   unless parameter :

Caching will be done if length of address is less than 64 (return-type).

@CachePut(value="addresses", unless="#result.length()<64")

public String getAddress(Customer customer) {...}

13.   Java based configuration :

@Configuration

@EnableCaching

public class CachingConfig {

    @Bean

    public CacheManager cacheManager() {

        SimpleCacheManager cacheManager = new SimpleCacheManager();

        cacheManager.setCaches(Arrays.asList(

          new ConcurrentMapCache("directory"),

          new ConcurrentMapCache("addresses")));

        return cacheManager;

    }

}

@Component

public class CustomerDataService {

  

    @Cacheable(value = "addresses", key = "#customer.name")

    public String getAddress(Customer customer) {

        return customer.getAddress();

    }

}

Some more examples :

14.   If key is not specified, then it uses hashcode of the class.

@Cacheable(value="books", key="#isbn")

public Book findStoryBook(ISBN isbn, boolean checkWarehouse, boolean includeUsed)

@Cacheable(value="books", key="#isbn.rawNumber")

public Book findStoryBook (ISBN isbn, boolean checkWarehouse, boolean includeUsed)

@Cacheable(value="books", key="T(classType).hash(#isbn)")

public Book findStoryBook (ISBN isbn, boolean checkWarehouse, boolean includeUsed)

15.   Disable cache –

spring.cache.type=none  

16.   Two caches –

spring.cache.cache-names=cache1,cache2