File download through REST means the server sends a stored file (PDF, image, report) back to the client as the HTTP response body. The server sets headers such as Content-Type and Content-Disposition so the browser or client knows what the file is and what to do with it. It is used for certificates, invoices, reports, […]
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File upload through REST lets a client send files (images, PDFs, documents) to a server along with normal form fields. It uses the multipart/form-data content type, which splits one HTTP request into several parts, each carrying a text field or a binary file. It is used for profile pictures, document submission, resume upload, and similar
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REST API Validation is the process of checking incoming HTTP request data to ensure that it satisfies the required constraints before the application processes it. In Spring Boot, validation is commonly implemented using Jakarta Bean Validation annotations such as @NotBlank, @NotNull, @Email, @Size, @Min, and @Max. By applying @Valid to a request body parameter in
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ResponseEntity is a Spring Framework class used to control the complete HTTP response returned by a REST API. It allows developers to specify the response body, HTTP status code, and HTTP headers according to the result of an operation. In Spring Boot applications, ResponseEntity is commonly used in REST controllers to return appropriate responses for
CRUD stands for Create, Read, Update and Delete, the four basic operations performed on application data.In REST, each operation is mapped to an HTTP method (POST, GET, PUT/PATCH, DELETE) on a resource URL such as /api/students.It is used because it gives every client (browser, mobile app, Postman) one standard, predictable way to manage data.Spring Boot
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REST is a style of building web APIs where everything is a resource (a student, an order) with its own URL, and the client works on it using standard HTTP methods.It is used because it is simple, works with any client (browser, mobile app, Postman), and follows rules everyone already knows.A request names the resource
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
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Custom validation lets you write your own rule when the standard annotations (@NotBlank, @Min, @Email) are not enough.It is used for application-specific rules, such as “a student is eligible only if the age is 17 to 25 and the marks reach the course cutoff”.You create an annotation, link it to a validator class that holds
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
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Bean Validation checks user input against rules written as annotations on the Java fields, such as @NotBlank, @Email and @Min.It is used so bad data (empty names, wrong emails, invalid mobile numbers) is rejected before it reaches your logic or the database.You put the rules on the model, add @Valid on the controller parameter, and
