8567402969
This commit extract spring-related links and recurring external links into asciidoctor attributes to be used by the Antora toolchain. It notably homogenizes links to: - IETF RFCs - Java Community Process JSRs - the Java API Documentation (on the Java 17 version) - Kotlin documentations (on the Kotlinlang.org version) - the Spring Boot reference guide (on the `html` version) This commit also reworks most link attributes to follow a Project-Category-Misc syntax. For example, `spring-boot-docs` rather than `docs-spring-boot`. Finally, it makes an effort to clean up remainders from the previous documentation toolchain, namely the `docs/asciidoc` folder and `modules/ROOT/pages/attributes.adoc` file. Closes gh-26864 Closes gh-31619
47 lines
1.9 KiB
Plaintext
47 lines
1.9 KiB
Plaintext
[[kotlin-extensions]]
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= Extensions
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Kotlin {kotlin-docs}/extensions.html[extensions] provide the ability
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to extend existing classes with additional functionality. The Spring Framework Kotlin APIs
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use these extensions to add new Kotlin-specific conveniences to existing Spring APIs.
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The {spring-framework-api-kdoc}/[Spring Framework KDoc API] lists
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and documents all available Kotlin extensions and DSLs.
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NOTE: Keep in mind that Kotlin extensions need to be imported to be used. This means,
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for example, that the `GenericApplicationContext.registerBean` Kotlin extension
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is available only if `org.springframework.context.support.registerBean` is imported.
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That said, similar to static imports, an IDE should automatically suggest the import in most cases.
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For example, {kotlin-docs}/inline-functions.html#reified-type-parameters[Kotlin reified type parameters]
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provide a workaround for JVM {java-tutorial}/java/generics/erasure.html[generics type erasure],
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and the Spring Framework provides some extensions to take advantage of this feature.
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This allows for a better Kotlin API `RestTemplate`, for the new `WebClient` from Spring
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WebFlux, and for various other APIs.
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NOTE: Other libraries, such as Reactor and Spring Data, also provide Kotlin extensions
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for their APIs, thus giving a better Kotlin development experience overall.
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To retrieve a list of `User` objects in Java, you would normally write the following:
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[source,java,indent=0]
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----
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Flux<User> users = client.get().retrieve().bodyToFlux(User.class)
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----
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With Kotlin and the Spring Framework extensions, you can instead write the following:
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[source,kotlin,indent=0]
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----
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val users = client.get().retrieve().bodyToFlux<User>()
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// or (both are equivalent)
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val users : Flux<User> = client.get().retrieve().bodyToFlux()
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----
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As in Java, `users` in Kotlin is strongly typed, but Kotlin's clever type inference allows
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for shorter syntax.
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