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1. Add Dependencies In pom.xml (for Maven) or build.gradle (for Gradle), add the following: Maven: <dependencies> <!-- Spring Boot starter for JPA --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <!-- PostgreSQL driver --> <dependency> <groupId>org.postgresql</groupId> <artifactId>postgresql</artifactId> <scope>runtime</scope> </dependency> <!-- Testcontainers dependencies --> <dependency> <groupId>org.testcontainers</groupId> <artifactId>testcontainers</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.testcontainers</groupId> <artifactId>postgresql</artifactId> <scope>test</scope> </dependency> <!-- Spring Boot Test…

1. What is Spring Boot? Spring Boot is a framework that simplifies creating standalone, production-ready Spring applications. It provides: Auto-configuration Embedded servers (Tomcat/Jetty) Opinionated defaults Easy dependency management 2. What is JUnit? JUnit is a testing framework for Java, mainly used for unit testing. With Spring Boot, we often use JUnit 5 along with…

Apache Camel is an open-source integration framework that helps developers connect different systems, applications, and services in a flexible and standardized way. It is primarily used for enterprise integration patterns (EIPs), which are common design patterns for integrating systems. from("file:input"). filter(body().contains("Camel")) .to("file:output");from("file:input"). filter(body().contains("Camel")) .to("file:output"); 1. Add Dependencies In pom.xml (Maven project), include: <dependencies> <!--…

1. What is Spring Batch? Spring Batch is a lightweight framework for batch processing, which is processing large volumes of data in chunks. Key features: Chunk-based processing Transaction management Retry and skip logic Job scheduling Integration with databases, files, queues, etc. 2. Basic Concepts TermDescriptionJobA batch process; contains one or more steps.StepA phase of…

Spring Boot Shell allows you to create interactive command-line applications using Spring Boot. It’s ideal for building CLI tools. Here’s a complete example: 1️⃣ Add Dependencies In your pom.xml (for Maven): <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <dependency> <groupId>org.springframework.shell</groupId> <artifactId>spring-shell-starter</artifactId> <version>3.1.2</version> <!-- Use latest --> </dependency> </dependencies> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <dependency> <groupId>org.springframework.shell</groupId> <artifactId>spring-shell-starter</artifactId>…

🔹 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…