DatabaseMetaData is a JDBC interface used to obtain information about the database, JDBC driver, tables, columns, and supported database features. It is obtained from a Connection object using the getMetaData() method. Using DatabaseMetaData, a Java program can dynamically inspect database information without directly querying system tables. This is useful for database administration, debugging, database migration […]
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
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A bean is an object that the Spring IoC container creates, configures, and manages for you, instead of you calling new. Spring finds beans by scanning for stereotype annotations (@Component, @Service, @Repository, @RestController) or by reading @Bean methods in a @Configuration class. It wires them together with dependency injection, so the Controller gets the Service
Metrics are numbers that describe how an application behaves while it runs, such as memory used, CPU load, request counts and response times. They are used to spot slow or overloaded applications, plan capacity and raise alerts before users notice a problem. Spring Boot Actuator collects JVM, system, web and database metrics automatically through Micrometer,
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Health monitoring means checking, through a URL, whether an application and the systems it depends on are working. It is used so that monitoring tools, load balancers and Kubernetes can detect a failing application automatically and react, for example by restarting it or stopping traffic to it. Spring Boot Actuator provides /actuator/health, which combines the
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.
OpenAPI is a standard, language-neutral format that formally describes a REST API: its URLs, methods, request bodies, responses and status codes. It is used so that developers, testers and client teams can understand and try an API without reading the source code. In Spring Boot, the springdoc library scans your controllers and generates the OpenAPI
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DatabaseMetaData is a JDBC interface used to obtain information about the database, JDBC driver, tables, columns, and supported database features. It is obtained from a Connection object using the getMetaData() method. Using DatabaseMetaData, a Java program can dynamically inspect database information without directly querying system tables. This is useful for database administration, debugging, database migration
Integration testing checks that several application layers work correctly together as one workflow. It is used to catch problems that unit tests miss, such as wrong wiring, wrong JSON mapping or a query that doesn’t match the service logic. Here a request goes through Controller, Service and Repository into a real MySQL test database, and
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Repository testing checks that JPA repository methods and queries work correctly against a real database. It is used to catch wrong derived-method names, wrong @Query JPQL and constraint problems early, before the service or controller layers run. @DataJpaTest loads only the JPA layer (entities and repositories), so the test starts quickly. Tests run against a
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