Code-based equivalents to popular Spring XML namespace elements <context:component-scan/>, <tx:annotation-driven/> and <mvc:annotation-driven> have been developed, most in the form of @Enable annotations. These are designed for use in conjunction with Spring's @Configuration classes, which were introduced in Spring 3.0.

The @ContextConfiguration annotation now supports supplying @Configuration classes for configuring the Spring TestContext. In addition, a new @ActiveProfiles annotation has been introduced to support declarative configuration of active bean definition profiles in ApplicationContext integration tests.

Prior to Spring 3.1, in order to inject against a property method it had to conform strictly to JavaBeans property signature rules, namely that any 'setter' method must be void-returning. It is now possible in Spring XML to specify setter methods that return any object type. This is useful when considering designing APIs for method-chaining, where setter methods return a reference to 'this'.

The new WebApplicationInitializer builds atop Servlet 3.0's ServletContainerInitializer support to provide a programmatic alternative to the traditional web.xml.

In standard JPA, persistence units get defined through META-INF/persistence.xml files in specific jar files which will in turn get searched for @Entity classes. In many cases, persistence.xml does not contain more than a unit name and relies on defaults and/or external setup for all other concerns (such as the DataSource to use, etc). For that reason, Spring 3.1 provides an alternative: LocalContainerEntityManagerFactoryBean accepts a 'packagesToScan' property, specifying base packages to scan for @Entity classes. This is analogous to AnnotationSessionFactoryBean's property of the same name for native Hibernate setup, and also to Spring's component-scan feature for regular Spring beans. Effectively, this allows for XML-free JPA setup at the mere expense of specifying a base package for entity scanning: a particularly fine match for Spring applications which rely on component scanning for Spring beans as well, possibly even bootstrapped using a code-based Servlet 3.0 initializer.

Spring 3.1 introduces a new set of support classes for processing requests with annotated controllers:

These classes are a replacement for the existing:

The new classes were developed in response to many requests to make annotation controller support classes more customizable and open for extension. Whereas previously you could configure a custom annotated controller method argument resolver, with the new support classes you can customize the processing for any supported method argument or return value type.

A second notable difference is the introduction of a HandlerMethod abstraction to represent an @RequestMapping method. This abstraction is used throughout by the new support classes as the handler instance. For example a HandlerInterceptor can cast the handler from Object to HandlerMethod and get access to the target controller method, its annotations, etc.

The new classes are enabled by default by the MVC namespace and by Java-based configuration via @EnableWebMvc. The existing classes will continue to be available but use of the new classes is recommended going forward.

Improved support for specifying media types consumed by a method through the 'Content-Type' header as well as for producible types specified through the 'Accept' header. See Section 16.3.2.4, “Consumable Media Types” and Section 16.3.2.5, “Producible Media Types”

Flash attributes can now be stored in a FlashMap and saved in the HTTP session to survive a redirect. For an overview of the general support for flash attributes in Spring MVC see Section 16.6, “Using flash attributes”.

In annotated controllers, an @RequestMapping method can add flash attributes by declaring a method argument of type RedirectAttributes. This method argument can now also be used to get precise control over the attributes used in a redirect scenario. See Section 16.3.3.10, “Specifying redirect and flash attributes” for more details.

URI template variables from the current request are used in more places:

An @RequestBody method argument can be annotated with @Valid to invoke automatic validation similar to the support for @ModelAttribute method arguments. A resulting MethodArgumentNotValidException is handled in the DefaultHandlerExceptionResolver and results in a 400 response code.

This new annotation provides access to the content of a "multipart/form-data" request part. See Section 16.10.5, “Handling a file upload request from programmatic clients” and Section 16.10, “Spring's multipart (file upload) support”.

A new UriComponents class has been added, which is an immutable container of URI components providing access to all contained URI components. A nenw UriComponentsBuilder class is also provided to help create UriComponents instances. Together the two classes give fine-grained control over all aspects of preparing a URI including construction, expansion from URI template variables, and encoding.

In most cases the new classes can be used as a more flexible alternative to the existing UriTemplate especially since UriTemplate relies on those same classes internally.

A ServletUriComponentsBuilder sub-class provides static factory methods to copy information from a Servlet request. See Section 16.7, “Building URIs”.