How do you implement caching in a Spring application?

Table of Contents

• Introduction
• Steps to Implement Caching in Spring
  • 1. Enable Caching in the Spring Configuration
  • 2. Define a Cache Provider
    • Maven Dependency:
    • EhCache XML Configuration (ehcache.xml):
  • 3. Annotate Methods with @Cacheable
  • 4. Customize Cache Keys
  • 5. Use @CachePut to Update the Cache
  • 6. Use @CacheEvict to Remove Data from the Cache
  • 7. Configure Cache Expiry and Size
• Practical Example of Caching in a Spring Boot Application
• Conclusion

Introduction

Caching is a technique that stores frequently used data in memory for faster retrieval, which helps reduce the load on the underlying data sources and improves overall application performance. In Spring, caching is easy to implement using the caching abstraction framework, which supports various cache providers like EhCache, Caffeine, Hazelcast, and more. This guide will walk you through how to implement caching in a Spring application using the @Cacheable annotation, along with other essential components like @CachePut and @CacheEvict.

Steps to Implement Caching in Spring

1. Enable Caching in the Spring Configuration

The first step to implement caching in a Spring application is to enable caching at the configuration level using the @EnableCaching annotation. This tells Spring to scan for any caching annotations like @Cacheable, @CachePut, and @CacheEvict and handle them accordingly.

2. Define a Cache Provider

Spring provides integration with several cache providers like EhCache, Caffeine, Hazelcast, and ConcurrentMapCache (the default in-memory cache). Choose a suitable cache provider and configure it in the application. Here's an example using EhCache:

Maven Dependency:

EhCache XML Configuration (ehcache.xml):

3. Annotate Methods with @Cacheable

Once caching is enabled, you can start caching method results by using the @Cacheable annotation on your service methods. The result of the method call will be stored in the cache, and subsequent calls with the same parameters will return the cached result without executing the method again.

4. Customize Cache Keys

By default, Spring uses the method parameters as the cache key. However, you can customize the cache key using the key attribute in the @Cacheable annotation.

5. Use @CachePut to Update the Cache

The @CachePut annotation is used when you want to update the cache every time the method is called, regardless of whether the result is already cached.

6. Use @CacheEvict to Remove Data from the Cache

The @CacheEvict annotation is used to remove a specific entry or clear the entire cache. This is particularly useful when you want to ensure the cache is in sync with the underlying data source after an update or delete operation.

To clear the entire cache:

7. Configure Cache Expiry and Size

For cache management, it's important to set a limit on cache size and specify how long cached data should be stored. In EhCache, this can be configured in the XML file:

This means the cache will hold up to 1000 entries, and the data will expire 600 seconds (10 minutes) after being stored.

Practical Example of Caching in a Spring Boot Application

Here’s a complete example of how caching works in a Spring Boot application:

Conclusion

Implementing caching in a Spring application can significantly enhance performance by reducing redundant method calls, database hits, and other expensive operations. The Spring framework’s caching abstraction, combined with annotations like @Cacheable, @CachePut, and @CacheEvict, provides a simple yet powerful mechanism for caching data. By choosing the right cache provider and properly managing cache size, expiry, and eviction policies, you can ensure that your application performs optimally without sacrificing data consistency.