Spring Boot Integration

Introduction

Running Redis from redis-cli teaches you the commands, but production applications need a client library. In the Java ecosystem, two drivers dominate—Jedis and Lettuce—while Spring Data Redis provides a convenient abstraction layer on top of either one. This chapter compares the drivers, shows how Spring Data Redis simplifies daily operations, and walks through a complete Spring Boot project that connects to Redis, caches method results, and implements a practical distributed lock.

Prerequisites

• Java 17 or newer
• Maven or Gradle installed
• Familiarity with Spring Boot basics
• A running Redis server (local or Docker) on port 6379

Jedis vs Lettuce

Both libraries are mature and well-supported. The choice usually comes down to threading model and API preference.

A Minimal Jedis Example

<!-- pom.xml -->
<dependency>
    <groupId>redis.clients</groupId>
    <artifactId>jedis</artifactId>
    <version>5.1.0</version>
</dependency>

A Minimal Lettuce Example

<!-- pom.xml -->
<dependency>
    <groupId>io.lettuce</groupId>
    <artifactId>lettuce-core</artifactId>
    <version>6.3.0.RELEASE</version>
</dependency>

Spring Data Redis

Spring Data Redis abstracts driver details behind familiar RedisTemplate and StringRedisTemplate APIs. It also provides annotation-driven caching that can replace manual Redis calls entirely.

Adding Dependencies

<!-- pom.xml -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>

No version is needed because Spring Boot manages it.

Connection Settings

Spring Boot auto-configures a StringRedisTemplate and a RedisConnectionFactory from these properties.

Using StringRedisTemplate

StringRedisTemplate uses StringRedisSerializer for both keys and values, which is what you want for most text-based caching.

Working with Hashes

Serialization: The JSON Problem

By default, RedisTemplate uses Java serialization, which produces unreadable binary data. For JSON storage, configure a custom RedisTemplate:

Annotation-Driven Caching

Spring Cache abstracts the cache provider entirely. Switching from an in-memory ConcurrentHashMap to Redis is a one-line configuration change.

Enable Caching

import org.springframework.cache.annotation.EnableCaching;
import org.springframework.context.annotation.Configuration;
 
@Configuration
@EnableCaching
public class CacheConfig {
}

Cache Annotations

Custom TTL per Cache

Spring Cache does not expose TTL directly in annotations. Define it in configuration:

Implementing a Distributed Lock

Distributed locks prevent multiple instances of your application from performing the same critical operation simultaneously. Redis makes this possible with SETNX (Set if Not eXists) and expiration.

Basic Lock with StringRedisTemplate

Connecting to Sentinel and Cluster

Spring Boot connects to Sentinel or Cluster with purely configuration changes—no code modifications required.

Sentinel

spring:
  data:
    redis:
      sentinel:
        master: mymaster
        nodes:
          - sentinel1.example.com:26379
          - sentinel2.example.com:26379
          - sentinel3.example.com:26379
      password: your-master-password

Cluster

spring:
  data:
    redis:
      cluster:
        nodes:
          - redis1.example.com:6379
          - redis2.example.com:6379
          - redis3.example.com:6379
        max-redirects: 3

The StringRedisTemplate and cache annotations work identically regardless of topology.

FAQ

Should I use Jedis or Lettuce with Spring Boot?

Use Lettuce unless you have a specific reason not to. It is the Spring Boot default, handles high concurrency without connection pools, and supports reactive programming.

Why does my cached object fail to deserialize?

Common causes: the class was moved or renamed, Jackson does not have a no-arg constructor, or the serializer was changed without clearing old cache entries. Set a TTL or manually flush the cache after deploys that change serialized classes.

Can I use Spring Cache with Redis Cluster?

Yes. The cache abstraction is agnostic to the underlying topology. Configure spring.data.redis.cluster.nodes and Spring Data Redis handles routing.

How do I monitor cache hit rates in Spring?

Enable Micrometer metrics:

management:
  metrics:
    enable:
      cache: true

Then observe cache.gets, cache.hits, and cache.misses in your metrics dashboard.

Is RedisTemplate thread-safe?

Yes. Once configured, RedisTemplate (and StringRedisTemplate) can be shared across multiple threads. Under Lettuce, the connection itself is multiplexed across threads safely.