Designed primarily for use in conjunction with web applications
to provide a convenient mechanism for configuring the container
programmatically.
ApplicationContextInitializer implementations are specified through the
new "contextInitializerClasses" servlet context parameter, then detected
and invoked by ContextLoader in its customizeContext() method.
In any case, the semantics of ApplicationContextInitializer's
initialize(ConfigurableApplicationContext) method require that
invocation occur *prior* to refreshing the application context.
ACI implementations may also implement Ordered/PriorityOrdered and
ContextLoader will sort instances appropriately prior to invocation.
Specifically, this new support provides a straightforward way to
programmatically access the container's Environment for the purpose
of adding, removing or otherwise manipulating PropertySource objects.
See Javadoc for further details.
Also note that ApplicationContextInitializer semantics overlap to
some degree with Servlet 3.0's notion of ServletContainerInitializer
classes. As Spring 3.1 development progresses, we'll likely see
these two come together and further influence one another.
DefaultWebEnvironment automatically adds a JndiPropertySource if
a "jndiPropertySourceEnabled" property is detected in any of the
other other default property sources.
* PropertySources is now an Iterable<PropertySource> in favor of
exposing an asList() method
* Otherwise reduced the set of methods exposed by PropertySources to the
absolute minimum
* Added Javadoc for both types and all methods
PropertySourcesPlaceholderConfigurer accommodates recent changes in
Environment and PropertySource APIs, e.g. no longer assuming enumerability
of property names.
PSPC reuses as much functionality as possible from
AbstractPropertyPlaceholderConfigurer, but overrides
postProcessBeanFactory() and defines its own variation on
processProperties() in order to accept a PropertyResolver rather than
a PropertySource.
AbstractPropertyPlaceholderConfigurer introduces doProcessProperties()
method to encapsulate that which is actually common, such as the
visiting of each bean definition once a StringValueResolver has been
created in the subclass.
* Environment now extends PropertyResolver
* Environment no longer exposes resolver and sources
* PropertySource is String,Object instead of String,String
* PropertySource no longer assumes enumerability of property names
* Introduced EnumerablePropertySource for those that do have enumerable property names
All existing *Aware interfaces have been refactored to extend this
new marker interface, serving two purposes:
* Easy access to a type hierarchy that can answer the question
"What *Aware interfaces are available?", without requiring
text-based searches. Also clearly excludes false positives like
TargetClassAware and ParamAware, which while similarly named,
are not semantically similar to traditional *Aware interfaces
in Spring.
* Minor potential performance improvements in
AbstractAutowireCapableBeanFactory and
ApplicationContextAwareProcessor. Both have blocks of sequential
instanceof checks in order to invoke any *Aware interface callback
methods. For a bean that implements none of these interfaces,
the whole sequence can be avoided by guarding first with
if (bean instanceof Aware) {
...
}
Implementors of custom *Aware-style interfaces (and presumably
the BeanPostProcessors that handle them), are encouraged to refactor to
extending this interface for consistency with the framework as well as
the points above.
Decomposed Environment interface into PropertySources, PropertyResolver
objects
Environment interface and implementations are still present, but
simpler.
PropertySources container aggregates PropertySource objects;
PropertyResolver provides search, conversion, placeholder
replacement. Single implementation for now is
PropertySourcesPlaceholderResolver
Renamed EnvironmentAwarePropertyPlaceholderConfigurer to
PropertySourcesPlaceholderConfigurer
<context:property-placeholder/> now registers PSPC by default, else
PPC if systemPropertiesMode* settings are involved
Refined configuration and behavior of default profiles
See Environment interface Javadoc for details
Added Portlet implementations of relevant interfaces:
* DefaultPortletEnvironment
* PortletConfigPropertySource, PortletContextPropertySource
* Integrated each appropriately throughout Portlet app contexts
Added protected 'createEnvironment()' method to AbstractApplicationContext
Subclasses can override at will to supply a custom Environment
implementation. In practice throughout the framework, this is how
Web- and Portlet-related ApplicationContexts override use of the
DefaultEnvironment and swap in DefaultWebEnvironment or
DefaultPortletEnvironment as appropriate.
Introduced "stub-and-replace" behavior for Servlet- and Portlet-based
PropertySource implementations
Allows for early registration and ordering of the stub, then
replacement with actual backing object at refresh() time.
Added AbstractApplicationContext.initPropertySources() method to
support stub-and-replace behavior. Called from within existing
prepareRefresh() method so as to avoid impact with
ApplicationContext implementations that copy and modify AAC's
refresh() method (e.g.: Spring DM).
Added methods to WebApplicationContextUtils and
PortletApplicationContextUtils to support stub-and-replace behavior
Added comprehensive Javadoc for all new or modified types and members
Added XSD documentation for all new or modified elements and attributes
Including nested <beans>, <beans profile="..."/>, and changes for
certain attributes type from xsd:IDREF to xsd:string
Improved fix for detecting non-file based Resources in
PropertiesLoaderSupport (SPR-7547, SPR-7552)
Technically unrelated to environment work, but grouped in with
this changeset for convenience.
Deprecated (removed) context:property-placeholder
'system-properties-mode' attribute from spring-context-3.1.xsd
Functionality is preserved for those using schemas up to and including
spring-context-3.0. For 3.1, system-properties-mode is no longer
supported as it conflicts with the idea of managing a set of property
sources within the context's Environment object. See Javadoc in
PropertyPlaceholderConfigurer, AbstractPropertyPlaceholderConfigurer
and PropertySourcesPlaceholderConfigurer for details.
Introduced CollectionUtils.toArray(Enumeration<E>, A[])
Work items remaining for 3.1 M2:
Consider repackaging PropertySource* types; eliminate internal use
of SystemPropertyUtils and deprecate
Further work on composition of Environment interface; consider
repurposing existing PlaceholderResolver interface to obviate need
for resolve[Required]Placeholder() methods currently in Environment.
Ensure configurability of placeholder prefix, suffix, and value
separator when working against an AbstractPropertyResolver
Add JNDI-based Environment / PropertySource implementatinos
Consider support for @Profile at the @Bean level
Provide consistent logging for the entire property resolution
lifecycle; consider issuing all such messages against a dedicated
logger with a single category.
Add reference documentation to cover the featureset.
Keith Donald
Chris Beams
Sam Brannen
Juergen Hoeller
Arjen Poutsma
Michael Isvy