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This commit adds a "spring-context-indexer" module that can be added to any project in order to generate an index of candidate components defined in the project. `CandidateComponentsIndexer` is a standard annotation processor that looks for source files with target annotations (typically `@Component`) and references them in a `META-INF/spring.components` generated file. Each entry in the index is the fully qualified name of a candidate component and the comma-separated list of stereotypes that apply to that candidate. A typical example of a stereotype is `@Component`. If a project has a `com.example.FooService` annotated with `@Component` the following `META-INF/spring.components` file is generated at compile time: ``` com.example.FooService=org.springframework.stereotype.Component ``` A new `@Indexed` annotation can be added on any annotation to instructs the scanner to include a source file that contains that annotation. For instance, `@Component` is meta-annotated with `@Indexed` now and adding `@Indexed` to more annotation types will transparently improve the index with additional information. This also works for interaces or parent classes: adding `@Indexed` on a `Repository` base interface means that the indexed can be queried for its implementation by using the fully qualified name of the `Repository` interface. The indexer also adds any class or interface that has a type-level annotation from the `javax` package. This includes obviously JPA (`@Entity` and related) but also CDI (`@Named`, `@ManagedBean`) and servlet annotations (i.e. `@WebFilter`). These are meant to handle cases where a component needs to identify candidates and use classpath scanning currently. If a `package-info.java` file exists, the package is registered using a "package-info" stereotype. Such files can later be reused by the `ApplicationContext` to avoid using component scan. A global `CandidateComponentsIndex` can be easily loaded from the current classpath using `CandidateComponentsIndexLoader`. The core framework uses such infrastructure in two areas: to retrieve the candidate `@Component`s and to build a default `PersistenceUnitInfo`. Rather than scanning the classpath and using ASM to identify candidates, the index is used if present. As long as the include filters refer to an annotation that is directly annotated with `@Indexed` or an assignable type that is directly annotated with `@Indexed`, the index can be used since a dedicated entry wil be present for that type. If any other unsupported include filter is specified, we fallback on classpath scanning. In case the index is incomplete or cannot be used, The `spring.index.ignore` system property can be set to `true` or, alternatively, in a "spring.properties" at the root of the classpath. Issue: SPR-11890
Spring Framework
The Spring Framework provides a comprehensive programming and configuration model for modern Java-based enterprise applications -- on any kind of deployment platform. A key element of Spring is infrastructural support at the application level: Spring focuses on the "plumbing" of enterprise applications so that teams can focus on application-level business logic, without unnecessary ties to specific deployment environments.
The framework also serves as the foundation for Spring Integration, Spring Batch and the rest of the Spring family of projects. Browse the repositories under the Spring organization on GitHub for a full list.
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This project adheres to the Contributor Covenant code of conduct. By participating, you are expected to uphold this code. Please report unacceptable behavior to spring-code-of-conduct@pivotal.io.
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Documentation
See the current Javadoc and reference docs.
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Prerequisites
Git and JDK 8 update 20 or later
Be sure that your JAVA_HOME environment variable points to the jdk1.8.0 folder
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Check out sources
git clone git@github.com:spring-projects/spring-framework.git
Import sources into your IDE
Run ./import-into-eclipse.sh or read import-into-idea.md as appropriate.
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Install all spring-* jars into your local Maven cache
./gradlew install
Compile and test; build all jars, distribution zips, and docs
./gradlew build
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License
The Spring Framework is released under version 2.0 of the Apache License.