5. New Features and Enhancements in Spring Framework 4.2

5.1 Core Container Improvements

  • Annotations such as @Bean get detected and processed on Java 8 default methods as well, allowing for composing a configuration class from interfaces with default @Bean methods.
  • Configuration classes may declare @Import with regular component classes now, allowing for a mix of imported configuration classes and component classes.
  • Configuration classes may declare an @Order value, getting processed in a corresponding order (e.g. for overriding beans by name) even when detected through classpath scanning.
  • @Resource injection points support an @Lazy declaration, analogous to @Autowired, receiving a lazy-initializing proxy for the requested target bean.
  • The application event infrastructure now offers an annotation-based model as well as the ability to publish any arbitrary event.

    • Any public method in a managed bean can be annotated with @EventListener to consume events.
    • @TransactionalEventListener provides transaction-bound event support.
  • Spring Framework 4.2 introduces first-class support for declaring and looking up aliases for annotation attributes. The new @AliasFor annotation can be used to declare a pair of aliased attributes within a single annotation or to declare an alias from one attribute in a custom composed annotation to an attribute in a meta-annotation.

    • The following annotations have been retrofitted with @AliasFor support in order to provide meaningful aliases for their value attributes: @Cacheable, @CacheEvict, @CachePut, @ComponentScan, @ComponentScan.Filter, @ImportResource, @Scope, @ManagedResource, @Header, @Payload, @SendToUser, @ActiveProfiles, @ContextConfiguration, @Sql, @TestExecutionListeners, @TestPropertySource, @Transactional, @ControllerAdvice, @CookieValue, @CrossOrigin, @MatrixVariable, @RequestHeader, @RequestMapping, @RequestParam, @RequestPart, @ResponseStatus, @SessionAttributes, @ActionMapping, @RenderMapping, @EventListener, @TransactionalEventListener.
    • For example, @ContextConfiguration from the spring-test module is now declared as follows:

      public @interface ContextConfiguration {
          String[] value() default {};
          String[] locations() default {};
          // ...
    • Similarly, composed annotations that override attributes from meta-annotations can now use @AliasFor for fine-grained control over exactly which attributes are overridden within an annotation hierarchy. In fact, it is now possible to declare an alias for the value attribute of a meta-annotation.
    • For example, one can now develop a composed annotation with a custom attribute override as follows.

      public @interface MyTestConfig {
          @AliasFor(annotation = ContextConfiguration.class, attribute = "value")
          String[] xmlFiles();
          // ...
    • See Spring Annotation Programming Model.
  • Numerous improvements to Spring’s search algorithms used for finding meta-annotations. For example, locally declared composed annotations are now favored over inherited annotations.
  • Composed annotations that override attributes from meta-annotations can now be discovered on interfaces and on abstract, bridge, & interface methods as well as on classes, standard methods, constructors, and fields.
  • Maps representing annotation attributes (and AnnotationAttributes instances) can be synthesized (i.e., converted) into an annotation.
  • The features of field-based data binding (DirectFieldAccessor) have been aligned with the current property-based data binding (BeanWrapper). In particular, field-based binding now supports navigation for Collections, Arrays, and Maps.
  • DefaultConversionService now provides out-of-the-box converters for Stream, Charset, Currency, and TimeZone. Such converters can be added individually to any arbitrary ConversionService as well.
  • DefaultFormattingConversionService comes with out-of-the-box support for the value types in JSR-354 Money & Currency (if the 'javax.money' API is present on the classpath): namely, MonetaryAmount and CurrencyUnit. This includes support for applying @NumberFormat.
  • @NumberFormat can now be used as a meta-annotation.
  • JavaMailSenderImpl has a new testConnection() method for checking connectivity to the server.
  • ScheduledTaskRegistrar exposes scheduled tasks.
  • Apache commons-pool2 is now supported for a pooling AOP CommonsPool2TargetSource.
  • Introduced StandardScriptFactory as a JSR-223 based mechanism for scripted beans, exposed through the lang:std element in XML. Supports e.g. JavaScript and JRuby. (Note: JRubyScriptFactory and lang:jruby are deprecated now, in favor of using JSR-223.)

5.2 Data Access Improvements

  • javax.transaction.Transactional is now supported via AspectJ.
  • SimpleJdbcCallOperations now supports named binding.
  • Full support for Hibernate ORM 5.0: as a JPA provider (automatically adapted) as well as through its native API (covered by the new org.springframework.orm.hibernate5 package).
  • Embedded databases can now be automatically assigned unique names, and <jdbc:embedded-database> supports a new database-name attribute. See "Testing Improvements" below for further details.

5.3 JMS Improvements

  • The autoStartup attribute can be controlled via JmsListenerContainerFactory.
  • The type of the reply Destination can now be configured per listener container.
  • The value of the @SendTo annotation can now use a SpEL expression.
  • The response destination can be computed at runtime using JmsResponse
  • @JmsListener is now a repeatable annotation to declare several JMS containers on the same method (use the newly introduced @JmsListeners if you’re not using Java8 yet).

5.4 Web Improvements

  • HTTP Streaming and Server-Sent Events support, see the section called “HTTP Streaming”.
  • Built-in support for CORS including global (MVC Java config and XML namespace) and local (e.g. @CrossOrigin) configuration. See Chapter 26, CORS Support for details.
  • HTTP caching updates:

    • new CacheControl builder; plugged into ResponseEntity, WebContentGenerator, ResourceHttpRequestHandler.
    • improved ETag/Last-Modified support in WebRequest.
  • Custom mapping annotations, using @RequestMapping as a meta-annotation.
  • Public methods in AbstractHandlerMethodMapping to register and unregister request mappings at runtime.
  • Protected createDispatcherServlet method in AbstractDispatcherServletInitializer to further customize the DispatcherServlet instance to use.
  • HandlerMethod as a method argument on @ExceptionHandler methods, especially handy in @ControllerAdvice components.
  • java.util.concurrent.CompletableFuture as an @Controller method return value type.
  • Byte-range request support in HttpHeaders and for serving static resources.
  • @ResponseStatus detected on nested exceptions.
  • UriTemplateHandler extension point in the RestTemplate.

    • DefaultUriTemplateHandler exposes baseUrl property and path segment encoding options.
    • the extension point can also be used to plug in any URI template library.
  • OkHTTP integration with the RestTemplate.
  • Custom baseUrl alternative for methods in MvcUriComponentsBuilder.
  • Serialization/deserialization exception messages are now logged at WARN level.
  • Default JSON prefix has been changed from "{} && " to the safer ")]}', " one.
  • New RequestBodyAdvice extension point and built-in implementation to support Jackson’s @JsonView on @RequestBody method arguments.
  • When using GSON or Jackson 2.6+, the handler method return type is used to improve serialization of parameterized types like List<Foo>.
  • Introduced ScriptTemplateView as a JSR-223 based mechanism for scripted web views, with a focus on JavaScript view templating on Nashorn (JDK 8).

5.5 WebSocket Messaging Improvements

  • Expose presence information about connected users and subscriptions:

    • new SimpUserRegistry exposed as a bean named "userRegistry".
    • sharing of presence information across cluster of servers (see broker relay config options).
  • Resolve user destinations across cluster of servers (see broker relay config options).
  • StompSubProtocolErrorHandler extension point to customize and control STOMP ERROR frames to clients.
  • Global @MessageExceptionHandler methods via @ControllerAdvice components.
  • Heart-beats and a SpEL expression 'selector' header for subscriptions with SimpleBrokerMessageHandler.
  • STOMP client for use over TCP and WebSocket; see Section 25.4.13, “STOMP Client”.
  • @SendTo and @SendToUser can contain destination variable placeholders.
  • Jackson’s @JsonView supported for return values on @MessageMapping and @SubscribeMapping methods.
  • ListenableFuture and CompletableFuture as return value types from @MessageMapping and @SubscribeMapping methods.
  • MarshallingMessageConverter for XML payloads.

5.6 Testing Improvements

  • JUnit-based integration tests can now be executed with JUnit rules instead of the SpringJUnit4ClassRunner. This allows Spring-based integration tests to be run with alternative runners like JUnit’s Parameterized or third-party runners such as the MockitoJUnitRunner.

  • The Spring MVC Test framework now provides first-class support for HtmlUnit, including integration with Selenium’s WebDriver, allowing for page-based web application testing without the need to deploy to a Servlet container.

  • AopTestUtils is a new testing utility that allows developers to obtain a reference to the underlying target object hidden behind one or more Spring proxies.

  • ReflectionTestUtils now supports setting and getting static fields, including constants.
  • The original ordering of bean definition profiles declared via @ActiveProfiles is now retained in order to support use cases such as Spring Boot’s ConfigFileApplicationListener which loads configuration files based on the names of active profiles.
  • @DirtiesContext supports new BEFORE_METHOD, BEFORE_CLASS, and BEFORE_EACH_TEST_METHOD modes for closing the ApplicationContext before a test — for example, if some rogue (i.e., yet to be determined) test within a large test suite has corrupted the original configuration for the ApplicationContext.
  • @Commit is a new annotation that may be used as a direct replacement for @Rollback(false).
  • @Rollback may now be used to configure class-level default rollback semantics.

    • Consequently, @TransactionConfiguration is now deprecated and will be removed in a subsequent release.
  • @Sql now supports execution of inlined SQL statements via a new statements attribute.
  • The ContextCache that is used for caching ApplicationContexts between tests is now a public API with a default implementation that can be replaced for custom caching needs.
  • DefaultTestContext, DefaultBootstrapContext, and DefaultCacheAwareContextLoaderDelegate are now public classes in the support subpackage, allowing for custom extensions.
  • TestContextBootstrappers are now responsible for building the TestContext.
  • In the Spring MVC Test framework, MvcResult details can now be logged at DEBUG level or written to a custom OutputStream or Writer. See the new log(), print(OutputStream), and print(Writer) methods in MockMvcResultHandlers for details.
  • The JDBC XML namespace supports a new database-name attribute in <jdbc:embedded-database>, allowing developers to set unique names for embedded databases –- for example, via a SpEL expression or a property placeholder that is influenced by the current active bean definition profiles.
  • Embedded databases can now be automatically assigned a unique name, allowing common test database configuration to be reused in different ApplicationContexts within a test suite.

  • MockHttpServletRequest and MockHttpServletResponse now provide better support for date header formatting via the getDateHeader and setDateHeader methods.