Configuration

@Configuration and @Bean

@Configuration
public class AppConfig {

    @Bean
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }

    @Bean
    public Clock clock() {
        return Clock.systemDefaultZone();
    }
}

Configuration Properties

@ConfigurationProperties(prefix = "app")
public class AppProperties {
    private String name;
    private int maxRetryCount;
    private List<String> supportedLanguages;

    // Getters and setters
}

@Configuration
@EnableConfigurationProperties(AppProperties.class)
public class AppConfig { }

application.properties

app.name=MyApp
app.max-retry-count=3
app.supported-languages=en,es,fr

Profile-Specific Configuration

application.properties          ← Common config
application-dev.properties     ← Development config
application-prod.properties    ← Production config
application-test.properties    ← Test config

Configuration

• Use properties over YAML for simple configs
• Externalize configuration
• Use profiles for environments
• Validate on startup

Bean Management

• Prefer constructor injection
• Use appropriate scope
• Implement lazy initialization
• Clean up resources

Security

• Use Spring Security
• Implement CSRF protection
• Use method-level security
• Log security events

Key Points

• Understanding Spring Configuration is essential for production systems
• Always consider scalability and maintainability
• Test thoroughly before deploying to production
• Monitor performance and set up alerting

Common Patterns

1. Validation: Always validate input at the boundary
2. Error Handling: Use structured error responses
3. Logging: Log key events for debugging
4. Testing: Unit, integration, and load tests
5. Documentation: Keep docs updated with code changes