spring-framework

Spring Framework

Chris Beams d9f7fdd120 Support reading nested annotations via ASM Background Spring 3.1 introduced the @ComponentScan annotation, which can accept an optional array of include and/or exclude @Filter annotations, e.g. @ComponentScan( basePackages = "com.acme.app", includeFilters = { @Filter(MyStereotype.class), ... } ) @Configuration public class AppConfig { ... } @ComponentScan and other annotations related to @Configuration class processing such as @Import, @ImportResource and the @Enable* annotations are parsed using reflection in certain code paths, e.g. when registered directly against AnnotationConfigApplicationContext, and via ASM in other code paths, e.g. when a @Configuration class is discovered via an XML bean definition or when included via the @Import annotation. The ASM-based approach is designed to avoid premature classloading of user types and is instrumental in providing tooling support (STS, etc). Prior to this commit, the ASM-based routines for reading annotation attributes were unable to recurse into nested annotations, such as in the @Filter example above. Prior to Spring 3.1 this was not a problem, because prior to @ComponentScan, there were no cases of nested annotations in the framework. This limitation manifested itself in cases where users encounter the ASM-based annotation parsing code paths AND declare @ComponentScan annotations with explicit nested @Filter annotations. In these cases, the 'includeFilters' and 'excludeFilters' attributes are simply empty where they should be populated, causing the framework to ignore the filter directives and provide incorrect results from component scanning. The purpose of this change then, is to introduce the capability on the ASM side to recurse into nested annotations and annotation arrays. The challenge in doing so is that the nested annotations themselves cannot be realized as annotation instances, so must be represented as a nested Map (or, as described below, the new AnnotationAttributes type). Furthermore, the reflection-based annotation parsing must also be updated to treat nested annotations in a similar fashion; even though the reflection-based approach has no problem accessing nested annotations (it just works out of the box), for substitutability against the AnnotationMetadata SPI, both ASM- and reflection-based implementations should return the same results in any case. Therefore, the reflection-based StandardAnnotationMetadata has also been updated with an optional 'nestedAnnotationsAsMap' constructor argument that is false by default to preserve compatibility in the rare case that StandardAnnotationMetadata is being used outside the core framework. Within the framework, all uses of StandardAnnotationMetadata have been updated to set this new flag to true, meaning that nested annotation results will be consistent regardless the parsing approach used. Spr9031Tests corners this bug and demonstrates that nested @Filter annotations can be parsed and read in both the ASM- and reflection-based paths. Major changes - AnnotationAttributes has been introduced as a concrete LinkedHashMap<String, Object> to be used anywhere annotation attributes are accessed, providing error reporting on attribute lookup and convenient type-safe access to common annotation types such as String, String[], boolean, int, and nested annotation and annotation arrays, with the latter two also returned as AnnotationAttributes instances. - AnnotationUtils#getAnnotationAttributes methods now return AnnotationAttributes instances, even though for binary compatibility the signatures of these methods have been preserved as returning Map<String, Object>. - AnnotationAttributes#forMap provides a convenient mechanism for adapting any Map<String, Object> into an AnnotationAttributes instance. In the case that the Map is already actually of type AnnotationAttributes, it is simply casted and returned. Otherwise, the map is supplied to the AnnotationAttributes(Map) constructor and wrapped in common collections style. - The protected MetadataUtils#attributesFor(Metadata, Class) provides further convenience in the many locations throughout the .context.annotation packagage that depend on annotation attribute introspection. - ASM-based core.type.classreading package reworked Specifically, AnnotationAttributesReadingVisitor has been enhanced to support recursive reading of annotations and annotation arrays, for example in @ComponentScan's nested array of @Filter annotations, ensuring that nested AnnotationAttributes objects are populated as described above. AnnotationAttributesReadingVisitor has also been refactored for clarity, being broken up into several additional ASM AnnotationVisitor implementations. Given that all types are package-private here, these changes represent no risk to binary compatibility. - Reflection-based StandardAnnotationMetadata updated As described above, the 'nestedAnnotationsAsMap' constructor argument has been added, and all framework-internal uses of this class have been updated to set this flag to true. Issue: SPR-7979, SPR-8719, SPR-9031		14 years ago
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.settings	Merge 3.1.0 development branch into trunk	16 years ago
src	Support reading nested annotations via ASM	14 years ago
.classpath	Convert CRLF=>LF on files missed earlier	14 years ago
.project	Added Eclipse project dependency on org.springframework.asm	15 years ago
build.xml	Added DomUtils.getChildElements() method. Also refactored ConfigBeanDefinitionParser.parse() to use it.	16 years ago
core.iml	Convert CRLF=>LF on files missed earlier	14 years ago
ivy.xml	Remove unnecessary javax.servlet dependency	15 years ago
pom.xml	Add <license> section to 3.1.x Maven poms	14 years ago
template.mf	Introduce CommandLinePropertySource and impls	15 years ago