java core

Spring Boot connects to a relational database by reading spring.datasource.* settings and building a DataSource, which is a pool of ready connections (HikariCP by default). JdbcTemplate sits on top of that DataSource and runs plain SQL for you, handling connections, statements, result sets, and cleanup. The four basic operations are INSERT (create), SELECT (read), UPDATE

Swagger UI is an interactive web page that displays your REST API and lets you call it directly from the browser. It is used so that developers and testers can explore endpoints, send real requests and see real responses without Postman. It reads the OpenAPI document (/v3/api-docs) and builds a clickable page from it automatically.

SMTP (Simple Mail Transfer Protocol) is the standard protocol applications use to send email through a mail server. Spring Boot connects to an SMTP server using the spring-boot-starter-mail dependency and spring.mail.* properties. It auto-creates a JavaMailSender bean, so you can send emails without writing any connection code. It is used for registration confirmations, password resets,

Validation error handling catches the exception that Spring throws when validation fails and turns it into a clear, structured response.It is used so the client gets “which field failed and why” instead of a long default Spring error or a server error. It is done with a @RestControllerAdvice class containing @ExceptionHandler methods, so one place

Working With Postgres Database Access refers to integrating and managing access to a PostgreSQL relational database within a Spring Boot application. PostgreSQL is known for its strong SQL standards compliance, robust extensibility, and advanced features (such as JSON/JSONB support and full-text search). Spring Boot provides seamless support for PostgreSQL through managed connection pooling, simplified query

Learn how to build, package, configure, and run a complete Spring Boot application as a standalone application. This capstone project combines the concepts learned in the previous sections, including Spring Boot Starters, Auto Configuration, Embedded Server, REST APIs, JPA, database connectivity, application properties, and Maven build commands. The project demonstrates how a Spring Boot application