Java enterprise web framework
REST controllers, JPA repositories, Spring Security, and integration tests for university Java coursework. The most common Spring Boot 3 grading deduction is forgetting that jakarta.persistence replaced javax.persistence, the migration our tutors patch in one line. Verified CS graduates from EPFL Lausanne, BITS Pilani, and Georgia Tech, starting at $20 per task, 12-hour average turnaround.
About
Spring Boot is the convention-over-configuration layer that sits on top of the Spring Framework and packages opinionated defaults for Java web applications. A single @SpringBootApplication annotation triggers component scanning, auto-configuration of an embedded Tomcat server on port 8080, JPA repository proxying, and ConfigurationProperties binding from application.yml. Where vanilla Spring required 40 lines of XML or Java config per data source, Spring Boot reduces it to 4 lines of application.yml plus a @Repository interface.
Students meet Spring Boot in junior-year courses (CS342 Software Design, CS420 Distributed Systems) when projects shift from terminal output to HTTP endpoints, and they meet it again in capstone work, microservices electives, and any internship that mentions enterprise Java. The framework runs on the JVM, builds with Maven or Gradle, and ships as an executable JAR that contains its own servlet container. Spring Boot 3 (the version most coursework now targets) requires Java 17 minimum and migrated from javax.* to jakarta.* package names, the breaking change that causes 60% of upgrade-related compilation failures we see on submitted assignments.
CSHH tutors deliver REST controllers with @RestController and @RequestMapping, JPA entities with @Entity and @ManyToOne mappings, Spring Security configuration using the new SecurityFilterChain bean (Spring Security 6 deprecated WebSecurityConfigurerAdapter), and integration tests using @SpringBootTest with @AutoConfigureMockMvc.
Coursework
CRUD endpoints for Course, Section, and Enrollment entities with @RestController, @RequestBody validation via Hibernate Validator (@NotBlank, @Min, @Max), and ResponseEntity wrapping for HTTP status codes. Tutors include integration tests with MockMvc covering happy path, 400 validation failures, and 404 not-found cases.
Product, Order, and Customer entities mapped through Spring Data JPA repositories. Includes @OneToMany with FetchType.LAZY plus a JPQL query using JOIN FETCH to avoid N+1 selects, transactional service layer with @Transactional, and Liquibase or Flyway migrations for schema versioning.
Spring Security 6 with the new SecurityFilterChain bean, custom OncePerRequestFilter for JWT validation, BCryptPasswordEncoder for password hashing, and role-based @PreAuthorize annotations on controller methods. Tutors include integration tests that obtain a token, then call protected endpoints.
Spring Cloud Eureka client registration, Feign declarative HTTP client for inter-service calls, Resilience4j circuit breaker around remote calls, and centralized config from Spring Cloud Config Server. Common in CS420 distributed systems labs.
STOMP over WebSocket with @MessageMapping handlers, SimpMessagingTemplate for server push, and an in-memory broker for development with a clear path to RabbitMQ or ActiveMQ for production. Includes integration tests using StompSessionHandler.
MultipartFile handling in a @PostMapping("/upload") endpoint, multipart configuration in application.yml (spring.servlet.multipart.max-file-size), and storage to either the local filesystem or AWS S3 via the AWS SDK. Tutors include MIME-type validation against an explicit allowlist.
Item reader from a CSV file, item processor with validation logic, item writer to a JPA repository, and a JobLauncher triggered by @Scheduled cron expression. Common in CS342 capstone projects for data pipeline assignments.
Debugging
// com.other.module.UserService
@Service
public class UserService { /* ... */ }
// com.example.app.Application
@SpringBootApplication
public class Application { /* default scan misses UserService */ }// com.example.app.Application
@SpringBootApplication
@ComponentScan(basePackages = {
"com.example.app",
"com.other.module"
})
public class Application { /* both packages scanned */ }@Entity
public class Order {
@OneToMany(fetch = FetchType.LAZY)
private List<LineItem> items;
}
// throws after the @Transactional method returns
order.getItems().forEach(System.out::println);public interface OrderRepository extends JpaRepository<Order, Long> {
@EntityGraph(attributePaths = "items")
Optional<Order> findById(Long id);
}
// items are loaded inside the session, no exceptionA JPA entity with @OneToMany(fetch = FetchType.LAZY) gets serialized after the persistence context closed (typically when the @Transactional service method returned). Spring tries to lazily load the collection, finds no session, and throws. Fix by either eager-fetching with @EntityGraph on the repository method, using JOIN FETCH in a JPQL query, or applying @Transactional at the controller level (anti-pattern but acceptable in coursework).
Browser blocks the cross-origin request because Spring did not emit Access-Control-Allow-Origin. Fix by annotating the controller with @CrossOrigin(origins = "http://localhost:3000") for development, or by registering a global WebMvcConfigurer with addCorsMappings for production. Spring Security 6 requires the CORS filter to be ordered before the security filter chain, otherwise the preflight OPTIONS request gets rejected with 401.
An integration test annotated @SpringBootTest cannot inject a dependency because the test slice does not load the full context. Use @SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT) to start the full server, or @WebMvcTest(MyController.class) plus @MockBean for the service dependencies when only the web layer needs testing.
A property defined in application.yml under custom.feature.enabled returns null when injected with @Value("${custom.feature.enabled}"). Likely causes: YAML indentation uses tabs instead of 2 spaces, the property sits in src/test/resources/application.yml but the test loads src/main/resources/application.yml (or vice versa), or a @PropertySource annotation overrides the default. Hit /actuator/env on the running server to see which property source supplied each key.
Tests using H2 in-memory database fail with "Database does not support COMMIT" or similar dialect-specific errors. Set spring.jpa.database-platform=org.hibernate.dialect.H2Dialect in application-test.yml, plus spring.jpa.hibernate.ddl-auto=create-drop to recreate schema between test runs.
Spring throws BeanCurrentlyInCreationException when two services @Autowire each other in their constructors. Spring Boot 2.6+ disables circular references by default. Fix by extracting the shared logic into a third service, using @Lazy on one of the injection points, or refactoring to setter injection (last resort, breaks immutability).
Code Examples
@RestController
@RequestMapping("/api/courses")
public class CourseController {
private final CourseRepository repo;
public CourseController(CourseRepository repo) {
this.repo = repo;
}
@GetMapping
public List<Course> all() {
return repo.findAll();
}
@PostMapping
public ResponseEntity<Course> create(@Valid @RequestBody Course course) {
Course saved = repo.save(course);
return ResponseEntity.status(HttpStatus.CREATED).body(saved);
}
}@Configuration
@EnableWebSecurity
public class SecurityConfig {
@Bean
SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
return http
.csrf(csrf -> csrf.disable())
.authorizeHttpRequests(auth -> auth
.requestMatchers("/api/public/**").permitAll()
.anyRequest().authenticated())
.addFilterBefore(jwtFilter, UsernamePasswordAuthenticationFilter.class)
.build();
}
}Related
FAQ
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