Component

Component Layer

📝 Note: This guide uses generic placeholder names to be reusable across any Spring Boot microservice. Replace with your actual implementation:

• {YourService} → Your service name (e.g., OrderService, PaymentService)
• BusinessService → Your core service (e.g., OrderService, UserService)
• DataService → Your data processing service (e.g., PaymentService, InventoryService)
• IntegrationService → Your external integration (e.g., PaymentGatewayService)
• {RequestType} → Your request DTO (e.g., CreateOrderRequest)
• {ResponseType} → Your response DTO (e.g., OrderResponse)

Overview

Spring @Component beans that integrate with Spring Boot framework features for type conversion and health monitoring.

Package: com.example.microserviceorch.component.example

Component Types

1. Type Converters

Automatic conversion of HTTP parameters to domain types via Spring's ConversionService.

Key Interface: Converter<String, EnumType>

2. Health Indicators

Custom health checks that integrate with Spring Boot Actuator for monitoring.

Key Interface: HealthIndicator

Quick Examples

Type Converter

@Component
public class EnumConverter implements Converter<String, EnumType> {
    @Override
    public EnumType convert(String value) {
        return EnumType.fromValue(value);
    }
}

Health Indicator

@Component
public class ServiceHealthIndicator implements HealthIndicator {
    @Autowired 
    private Environment environment;
    
    @Autowired 
    private BuildProperties buildProperties;

    @Override
    public Health health() {
        return Health.up()
            .withDetail("environment", String.join(",", environment.getActiveProfiles()))
            .withDetail("version", buildProperties.getVersion())
            .build();
    }
}

Core Principles

1. Stateless or Thread-Safe: Components are singletons
2. Pure Conversion: No business logic in converters
3. Lightweight Health Checks: Fast metadata retrieval only
4. Dependency Injection: Constructor injection preferred
5. Automatic Registration: Via component scanning

Documentation

• Type Converters Guide - Converter implementation and patterns
• Health Indicators Guide - Health check integration
• Testing Guide - Unit and integration tests

Examples

See /examples/ for:

• EnumConverter.java - String-to-enum converter
• EnumType.java - Enum with JSON support
• ServiceHealthIndicator.java - Service metadata health check
• EnumConverterTest.java - Converter unit tests
• ServiceHealthIndicatorTest.java - Health indicator unit tests

Design Patterns

• Strategy Pattern: Different converters for different types
• Template Method: HealthIndicator interface
• Singleton Pattern: Component scope
• Adapter Pattern: Type conversion

Anti-Patterns

❌ Business logic in converters
❌ Expensive operations in health checks
❌ Stateful components without thread safety
❌ Manual dependency creation

Code Formatting

All code uses Spotless with Google Java Format (AOSP):

./gradlew spotlessApply