What’s New in Spring Boot 3.5? 13 Must‑Know Features for Java Backend Developers

Spring Boot 3.5 is scheduled for release this month, bringing a range of notable improvements for Java backend developers.

Task scheduling enhancement : TaskDecorator optimizes scheduled tasks.

Vibur connection pool : A high‑performance database connection option.

Security monitoring upgrade : SSL certificate status is clearly visible.

Configuration management optimization : More flexible handling of environment variables and configurations.

Link tracing improvement : Trace ID is automatically written to HTTP response headers.

Actuator experience boost : Comprehensive enhancements to Actuator functionality.

Functional programming support : Early access to Spring Framework 7 features.

New Features Details

1. TaskDecorator: More Powerful Scheduled Tasks

Spring Boot 3.5 automatically applies a TaskDecorator bean from the application context to all scheduled task executors.

<code>@Bean
public TaskDecorator myTaskDecorator() {
    return taskDecorator -> {
        // Retrieve main‑thread context information
        String userId = UserContext.getCurrentUserId();
        // Return the wrapped task
        return () -> {
            // Set context in the child thread
            ...
        };
    };
}
</code>

This eliminates boiler‑plate code and makes passing security context and MDC log information trivial, especially for multi‑tenant or unified permission scenarios.

2. Vibur Connection Pool: A New Performance‑Optimized Choice

In addition to HikariCP, Tomcat, DBCP2 and OracleUcp, Spring Boot 3.5 adds support for the Vibur DBCP connection pool.

<code>spring:
  datasource:
    type: io.vibur.dbcp.ViburDBCPDataSource
</code>

Vibur DBCP offers advanced performance monitoring, slow‑SQL detection, thread‑hunger prevention, and JDBC statement caching, making it suitable for applications with stringent database performance requirements.

3. SSL Bundle Metrics: Clear Security Monitoring

Actuator now provides health metrics for SSL certificate chains, categorising them as valid, expired, about‑to‑expire, or not‑yet‑valid.

<code>management:
  endpoints:
    web:
      exposure:
        include: health,info,ssl
  ssl:
    bundles:
      enabled: true
</code>

Operations teams can monitor SSL status in real time and avoid service interruptions caused by expired certificates.

4. Environment Variable Config Loading: Easier Multi‑Environment Deployment

Spring Boot 3.5 allows loading multiple configuration properties from a single environment variable, simplifying containerised deployments.

<code># In application.yml
spring:
  config:
    import: env:MY_CONFIGURATION

# Set environment variable
MY_CONFIGURATION='datasource.url=jdbc:mysql://prod-db:3306/myapp
datasource.username=prod_user
datasource.password=prod_password'
</code>

This approach reduces the need for numerous individual environment variables in Docker and Kubernetes setups.

5. Actuator‑Triggered Quartz Jobs: Smarter Operations

Quartz jobs can now be triggered via an HTTP endpoint, eliminating the need to wait for a scheduled time.

<code># Trigger a specific Quartz job
curl -X POST http://localhost:8080/actuator/quartz/jobs/DEFAULT/syncDataJob
</code>

Operators can manually start tasks with a simple request, greatly improving response speed in urgent situations.

6. HTTP Response Header Trace ID: Seamless Distributed Tracing

When integrated with Micrometer Observations and Tracing, Spring Boot automatically writes the Trace ID to HTTP response headers.

<code>management:
  observations:
    http:
      server:
        requests:
          write-trace-header: true
</code>

This enables front‑end services to capture the Trace ID for reporting, enhancing end‑to‑end fault diagnosis.

7. Structured Log Stacktrace Customisation

Spring Boot 3.5 allows customisation of stack‑trace output in structured JSON logs.

<code>logging:
  structured:
    json:
      stacktrace:
        max-depth: 20
        packaged-only: true
        include-packages: com.mycompany
        exclude-packages: org.springframework,java.lang
</code>

Only business‑code stack frames are emitted, making logs clearer and issue localisation more precise.

8. WebMvc Functional Routing Information

The Mappings endpoint now includes detailed information about WebMvc.fn functional routes.

<code>@Bean
public RouterFunction<ServerResponse> routerFunction() {
    return route()
        .GET("/api/users", this::getAllUsers)
        .POST("/api/users", this::createUser)
        .build();
}
</code>

9. Service Connection SSL Support

Client‑side SSL support has been added for various services such as Cassandra, Couchbase, Elasticsearch, Kafka, MongoDB, RabbitMQ, and Redis.

<code>spring:
  data:
    mongodb:
      ssl:
        enabled: true
        bundle: mongodb-bundle
  ssl:
    bundles:
      mongodb-bundle:
        keystore:
          location: classpath:mongodb-keystore.p12
          password: secret
        type: PKCS12
</code>

This simplifies secure communication configuration for backend services.

10. OpenTelemetry Improvements

Configuration properties and environment variables can now set OpenTelemetry resource attributes, including support for

service.namespace

.

<code>management:
  tracing:
    opentelemetry:
      resource:
        attributes:
          service.name: my-service
          service.namespace: my-group
      export:
        otlp:
          endpoint: http://tempo:4317
</code>

11. Spring Batch Enhancements

Custom

JobParametersConverter

can be defined and transaction‑state validation can be controlled.

<code>@Bean
public JobParametersConverter customJobParametersConverter() {
    return new MyCustomJobParametersConverter();
}

spring:
  batch:
    jdbc:
      validate-transaction-state: false
</code>

12. OAuth 2.0 JWT Profile: Standardised Authentication

Spring Security 6.5.0 adds support for RFC 9068, standardising the JWT format of OAuth 2.0 access tokens.

<code>@Bean
public JwtEncoder jwtEncoder() {
    return new NimbusJwtEncoder(jwkSource());
}

@Bean
public OAuth2TokenCustomizer<JwtEncodingContext> jwtCustomizer() {
    return context -> {
        JwtClaimsSet.Builder claims = context.getClaims();
        claims.claim("client_id", context.getRegisteredClient().getClientId());
        // Additional RFC 9068 claims
    };
}
</code>

13. Functional Bean Registration: Preview Spring 7 Features

The

BeanRegistrar

interface enables functional bean registration, offering a more flexible alternative to

@Conditional

for dynamic bean creation.

<code>public class MyBeanRegistrar implements BeanRegistrar {
    @Override
    public void registerBeans(BeanRegistry registry, Environment environment) {
        // Dynamically register beans based on conditions
        if (environment.containsProperty("feature.enabled")) {
            registry.registerBean(MyService.class, MyService::new);
        }
    }
}

@Import(MyBeanRegistrar.class)
@Configuration
public class AppConfig {
    // ...
}
</code>