Cache Data in Spring Boot with Hazelcast and JCache

What You’ll Learn

This guide will get you started with Hazelcast as a JCache provider for your Spring Boot application.

Before you Begin

JDK 1.8+
Apache Maven 3.2+

Spring Boot Application

To leverage JCache in your Spring Boot application, you will need to do the following:

Add org.springframework.boot:spring-boot-starter-cache dependency
Add @EnableCaching annotation to your main class
Add @CacheResult(cacheName = "books") annotation to every method you want to cache
Add spring.cache.type=jcache to your application.properties file

For more explanation on the Spring Boot and JCache topic, please check the related Spring Boot blog post: Cache Abstraction: JCache.

The application will be a simple web service with two classes defined as follows:

BookController.java

@RestController
@RequestMapping("/books")
public class BookController {

    private final BookService bookService;

    BookController(BookService bookService) {
        this.bookService = bookService;
    }

    @GetMapping("/{isbn}")
    public String getBookNameByIsbn(@PathVariable("isbn") String isbn) {
        return bookService.getBookNameByIsbn(isbn);
    }
}

BookService.java

@Service
public class BookService {
    @CacheResult(cacheName = "books")
    public String getBookNameByIsbn(String isbn) {
        return findBookInSlowSource(isbn);
    }

    private String findBookInSlowSource(String isbn) {
        // some long processing
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            throw new RuntimeException(e);
        }
        return "Sample Book Name";
    }
}

The idea is that every call to the endpoint /books/<isbn> goes to the findBookNameByIsbn() method, which would attempt to return cached results.

If there’s no cached value, this method is executed and results cached.

Use Hazelcast as JCache Provider

To use Hazelcast as the JCache provider, all you have to do is to add Hazelcast to your classpath:

pom.xml

<dependency>
    <groupId>com.hazelcast</groupId>
    <artifactId>hazelcast</artifactId>
    <version>4.2.2</version>
</dependency>

Then, you need to create a Hazelcast configuration with the books map configured. You can define it as src/main/resources/hazelcast.yaml.

hazelcast.yaml

hazelcast:
  cache:
    books:
      management-enabled: true

Finally, you can configure your application to use Hazelcast. You can use either client-server or embedded topology.

Configure for Client-Server

You first need to start a Hazelcast server with the Hazelcast configuration defined in the previous step.

Docker
CLI

docker run --rm -p 5701:5701 -v $(pwd)/modules/ROOT/examples/src/main/resources:/hazelcast -e JAVA_OPTS="-Dhazelcast.config=/hazelcast/hazelcast.yaml" hazelcast/hazelcast

# Install Hazelcast CLI as described at
# https://github.com/hazelcast/hazelcast-command-line#installation

wget https://repo1.maven.org/maven2/javax/cache/cache-api/1.1.1/cache-api-1.1.1.jar
hz start -c src/main/resources/hazelcast.yaml -j cache-api-1.1.1.jar

Then, use the following application.properties for your Spring Boot application.

application.properties

spring.cache.type=jcache
spring.cache.jcache.provider=com.hazelcast.client.cache.HazelcastClientCachingProvider
spring.hazelcast.config=classpath:hazelcast-client.yaml

To start the application, run the following command from the modules/ROOT/examples directory.

mvn spring-boot:run

Configure for Embedded

If you prefer to run Hazelcast embedded in your Spring Boot application, then you need to use the following application-embedded.properties file.

application-embedded.properties

spring.cache.type=jcache
spring.cache.jcache.provider=com.hazelcast.cache.impl.HazelcastServerCachingProvider
spring.hazelcast.config=classpath:hazelcast.yaml

To start the application, run the following command from the modules/ROOT/examples directory.

mvn spring-boot:run -Dspring-boot.run.profiles=embedded

Test the Application

You should see that your application is successfully connected to Hazelcast.

Members {size:1, ver:1} [
        Member [172.30.63.9]:5701 - 75cd0b19-ee36-4e0a-9d9c-38c49f67f842 this
]

Then, you can test the application by executing the following command.

curl localhost:8080/books/12345

You should see the following:

Sample Book Name

The first time you execute this command, it should take some time to get the response. However, when you try it again, it should be instant. That means that the cache is used.

If you want to learn more about the topics in this tutorial, see the following resources:

Hazelcast JCache