🔹 What is AOP? AOP lets you separate cross-cutting concerns (like logging, security, transactions, caching) from business logic.In Spring Boot, AOP is usually implemented using Spring AOP with annotations like @Aspect. 🔹 Key Concepts Aspect → @Aspect Advice → @Before, @After, @AfterReturning, @AfterThrowing, @Around Pointcut → @Pointcut Join Point → (no annotation; accessible via…
A Resource Server is an application that serves protected resources and validates access tokens issued by an Authorization Server (like Keycloak, Okta, Auth0, or a custom Authorization Server). 🔑 Core Concepts Authorization Server → Issues tokens (JWT, opaque). Example: Keycloak, Auth0. Resource Server → Your Spring Boot REST API that checks tokens before serving…
🔑 What is Okta? Okta is an identity management platform that provides authentication, authorization, and user management. Instead of building your own login system, you can use Okta as your identity provider (IdP). ⚙️ Setup: Spring Boot + Okta 1. Create an Okta Developer Account Sign up at Okta Developer. Log in → go…
Spring Boot integrates very well with HashiCorp Vault to securely manage secrets (like DB credentials, API keys, tokens) instead of hardcoding them in application.properties. Here’s a step-by-step guide with example: 🔹 1. Setup Vault Install Vault locally (or use Docker): docker run --cap-add=IPC_LOCK -d --name=dev-vault -p 8200:8200 vault:latest Start Vault in dev mode: vault…
🔹 What is CORS? By default, a browser blocks frontend apps running at a different origin (e.g., http://localhost:3000) from calling APIs at another origin (e.g., http://localhost:8080). CORS is a mechanism that allows servers to specify which origins are allowed. 🔹 Ways to Enable CORS in Spring Boot 1. Enable CORS on a specific controller…
🔐 Spring Security + Keycloak Flow Schema [Client Request] │ │ GET /admin/dashboard ▼ ┌─────────────────────────────┐ │ Spring Security Filter Chain│ │ ────────────────────────── │ │ Filters: │ │ - OAuth2LoginAuthentication │ │ - BearerTokenAuthentication │ │ - SecurityContextPersistence │ └─────────────────────────────┘ │ │ No authentication? ▼ ┌─────────────────────────────┐ │ Redirect to Keycloak Login │ │ (Authorization Endpoint)…
1. Add dependencies In your pom.xml (for Maven) include: <dependencies> <!-- Spring Boot Starter Test --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <!-- WireMock for mocking HTTP services --> <dependency> <groupId>com.github.tomakehurst</groupId> <artifactId>wiremock-jre8</artifactId> <version>2.35.0</version> <scope>test</scope> </dependency> <!-- Optional: RestTemplate if using it for HTTP calls --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> </dependencies> <dependencies> <!-- Spring Boot Starter…
1️⃣ Project Structure spring-security-demo/ ├── lib/ # Put all Spring Boot JARs here ├── src/ │ └── main/ │ └── java/ │ └── com/example/demo/ │ ├── DemoApplication.java │ ├── SecurityConfig.java │ ├── UserController.java │ └── CustomUserDetailsService.java spring-security-demo/ ├── lib/ # Put all Spring Boot JARs here ├── src/ │ └── main/ │ └── java/…
Caffeine is a high-performance, near-optimal caching library for Java that integrates very well with Spring Boot. It provides features like size-based eviction, time-based expiration, refresh, and statistics. Here’s a step-by-step guide with example: 1. Add Dependencies In Maven: <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-cache</artifactId> </dependency> <dependency> <groupId>com.github.ben-manes.caffeine</groupId> <artifactId>caffeine</artifactId> <version>3.1.8</version> <!-- use latest --> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-cache</artifactId>…
1. Setup Maven Dependencies In your pom.xml: <dependencies> <!-- Spring Boot Web --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <!-- Spring Data Elasticsearch --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-elasticsearch</artifactId> </dependency> <!-- Lombok (optional, for getters/setters) --> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <optional>true</optional> </dependency> <!-- Spring Boot Test --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <dependencies> <!-- Spring Boot Web -->…