How do you implement caching with Spring Boot?

Table of Contents

Introduction

Caching is an essential technique in software development for improving performance by storing and reusing previously computed results. In a Spring Boot application, caching can significantly reduce the load on databases, external APIs, and other expensive operations. Spring Boot provides a comprehensive caching abstraction that supports various cache providers such as EhCache, Redis, and in-memory caches.

This guide will walk you through how to implement caching in a Spring Boot application, covering the use of Spring's caching annotations, configuration, and integrating popular caching providers.

1. Setting Up Caching in Spring Boot

To use caching in a Spring Boot application, you first need to enable caching by adding the @EnableCaching annotation in a configuration class.

Step 1: Enable Caching

The @EnableCaching annotation tells Spring to scan for caching annotations like @Cacheable, @CacheEvict, and @CachePut in your application, allowing you to easily apply caching to methods.

2. Using Caching Annotations

Spring Boot provides several annotations that help implement caching easily. Let’s go over the main ones:

@Cacheable

The @Cacheable annotation is used to mark methods whose results should be cached. When a method is annotated with @Cacheable, Spring will first check if the result is already in the cache. If it is, Spring returns the cached result; otherwise, it executes the method and caches the result for subsequent calls.

Example: Using @Cacheable

In this example:

  • The getUserById method is annotated with @Cacheable, which tells Spring to cache the result of this method call.
  • value = "users": The name of the cache where the result will be stored.
  • key = "#userId": The cache key, based on the method's input parameter userId.

@CachePut

The @CachePut annotation is used when you want to update the cache without interfering with the method's execution. It is typically used for write-through caching, where you update the cache after modifying the data.

Example: Using @CachePut

In this example:

  • @CachePut ensures that the updated User is cached, replacing any existing cache entry with the same key (#user.id).

@CacheEvict

The @CacheEvict annotation is used to remove one or more entries from the cache. This is typically used when data is modified, and you want to ensure that outdated cached results are cleared.

Example: Using @CacheEvict

In this example:

  • @CacheEvict ensures that when the deleteUser method is called, the cache entry associated with the userId is removed.

@Cacheable with Conditional Caching

Sometimes you may want to cache results conditionally. You can achieve this by using the condition or unless attributes in @Cacheable annotations.

Example: Conditional Caching

Here, the result is cached only if productId > 10.

3. Configuring Cache Providers

Spring Boot supports various caching providers, such as EhCache, Redis, and simple in-memory caches. You can choose one based on your application's needs. Below are examples of how to configure caching with some of these providers.

In-Memory Cache (Simple)

Spring Boot supports a simple in-memory cache by default. You don't need any extra configuration to use it, as Spring automatically sets up a ConcurrentMapCache.

Example: Using In-Memory Cache

Spring will automatically use a basic in-memory cache to store the data.

EhCache Configuration

EhCache is a popular, robust caching solution that works well for both small and large applications.

Step 1: Add EhCache Dependency

Add the following dependency to your pom.xml (if you're using Maven):

Step 2: Configure EhCache in application.yml

spring:  cache:    type: ehcache

Create an ehcache.xml file to configure EhCache settings:

Redis Configuration

Redis is an in-memory data structure store that can be used as a distributed cache for Spring Boot applications.

Step 1: Add Redis Dependency

Add the following dependency to your pom.xml:

Step 2: Configure Redis in application.yml
Step 3: Enable Redis Caching

4. Cache Management Example

Here’s a full example combining @Cacheable, @CacheEvict, and a Redis cache provider:

In this example:

  • getProductById is cached in Redis when called.
  • deleteProduct clears the corresponding cache entry when the product is deleted.

5. Cache Management and Best Practices

  • Cache Expiry: Set a reasonable cache expiry time to avoid stale data in the cache.
  • Eviction Policy: Use eviction policies such as LRU (Least Recently Used) to manage memory effectively.
  • Cache Size: Limit the size of your cache to avoid memory overflow or excessive cache sizes.

Conclusion

Caching in Spring Boot is a powerful way to enhance performance by reducing redundant calculations and improving response times. Using annotations like @Cacheable, @CachePut, and

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