@CacheEvict for invalidation in Spring Boot - Mini Project: Build & Apply

Using @CacheEvict for Cache Invalidation in Spring Boot

📖 Scenario: You are building a simple Spring Boot service that manages user profiles. To improve performance, you cache user data. When a user profile is updated, you need to clear the cached data to keep it fresh.

🎯 Goal: Build a Spring Boot service with a method to cache user profiles and another method to update profiles that uses @CacheEvict to clear the cache for the updated user.

📋 What You'll Learn

Create a simple UserService class with a method getUserById that returns a user name string.

Add a cache configuration to cache the result of getUserById.

Create an updateUserName method that updates the user name and uses @CacheEvict to clear the cache for that user ID.

Ensure the cache is cleared only for the specific user ID when updateUserName is called.

💡 Why This Matters

🌍 Real World

Caching user data improves performance by avoiding repeated database calls. Clearing cache on updates ensures users see fresh data.

💼 Career

Understanding cache invalidation with <code>@CacheEvict</code> is essential for backend developers working with Spring Boot to build efficient and consistent applications.

1

Create UserService with getUserById method

Create a class called UserService with a method getUserById that takes a Long userId parameter and returns a String user name. For now, return the string "User" + userId.

Spring Boot

public class UserService {
    // Your code here
}

Need a hint?

Define a public class UserService. Inside it, create a public method getUserById that returns a string combining "User" and the userId.

2

Enable caching and add @Cacheable to getUserById

Add the @Cacheable annotation to the getUserById method with cache name "users". Also, add the @Service annotation to the UserService class to make it a Spring service.

Spring Boot

@Service
public class UserService {
    @Cacheable("users")
    public String getUserById(Long userId) {
        return "User" + userId;
    }
    // Your code here
}

Need a hint?

Use @Service on the class and @Cacheable("users") on the getUserById method to enable caching.

3

Add updateUserName method with @CacheEvict

Add a method updateUserName that takes Long userId and String newName parameters. Annotate it with @CacheEvict(cacheNames = "users", key = "#userId") to clear the cache for that user ID. Inside the method, simulate updating by returning newName.

Spring Boot

import org.springframework.cache.annotation.CacheEvict;
// Add updateUserName method below

@Service
public class UserService {
    @Cacheable("users")
    public String getUserById(Long userId) {
        return "User" + userId;
    }
    // Your code here
}

Need a hint?

Create updateUserName method annotated with @CacheEvict to clear cache for the given userId.

4

Add @EnableCaching to application configuration

Create a configuration class called CacheConfig annotated with @Configuration and @EnableCaching to enable Spring caching support.

Spring Boot

import org.springframework.context.annotation.Configuration;
import org.springframework.cache.annotation.EnableCaching;

// Your code here

Need a hint?

Create a class CacheConfig with @Configuration and @EnableCaching annotations to activate caching.