Java Spring Patterns

Java Spring Patterns Skill

Purpose

This skill establishes the coding standards and patterns for Java 21+ with Spring Boot 3.x. All generated code should follow these conventions for consistency across the codebase. This serves as the primary reference for code generation decisions.

Java 21+ Features

Records for DTOs

Use records for all immutable data carriers — request DTOs, response DTOs, and value objects:

// Request DTO with validation
public record CreateFieldRequest(
    @NotBlank String fieldName,
    @NotBlank String fieldType,
    String format,
    String description,
    boolean required,
    @NotBlank String schemaName
) {}

// Response DTO
public record FieldResponse(
    Long id,
    String fieldName,
    String fieldType,
    String format,
    String description,
    boolean required,
    String schemaName,
    Instant createdAt
) {
    public static FieldResponse from(ApiField entity) {
        return new FieldResponse(
            entity.getId(),
            entity.getFieldName(),
            entity.getFieldType(),
            entity.getFormat(),
            entity.getDescription(),
            entity.isRequired(),
            entity.getSchemaName(),
            entity.getCreatedAt()
        );
    }
}

// Paginated response wrapper
public record PageResponse<T>(
    List<T> content,
    int page,
    int size,
    long totalElements,
    int totalPages,
    boolean hasNext
) {
    public static <T> PageResponse<T> from(Page<T> page) {
        return new PageResponse<>(
            page.getContent(),
            page.getNumber(),
            page.getSize(),
            page.getTotalElements(),
            page.getTotalPages(),
            page.hasNext()
        );
    }
}