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Ahead-of-Time Processing
Spring AOT is a process that analyzes your code at build-time in order to generate an optimized version of it. It is most often used to help generate GraalVM native images.
The Spring Boot Gradle plugin provides tasks that can be used to perform AOT processing on both application and test code. The tasks are configured automatically when the GraalVM Native Image plugin is applied:
-
Groovy
-
Kotlin
plugins {
id 'org.springframework.boot' version '3.4.0-M1'
id 'org.graalvm.buildtools.native' version '0.10.2'
id 'java'
}
plugins {
id("org.springframework.boot") version "3.4.0-M1"
id("org.graalvm.buildtools.native") version "0.10.2"
java
}
Processing Applications
Based on your @SpringBootApplication
-annotated main class, the processAot
task generates a persistent view of the beans that are going to be contributed at runtime in a way that bean instantiation is as straightforward as possible.
Additional post-processing of the factory is possible using callbacks.
For instance, these are used to generate the necessary reflection configuration that GraalVM needs to initialize the context in a native image.
As the BeanFactory
is fully prepared at build-time, conditions are also evaluated.
This has an important difference compared to what a regular Spring Boot application does at runtime.
For instance, if you want to opt-in or opt-out for certain features, you need to configure the environment used at build time to do so.
To this end, the processAot
task is a JavaExec
task and can be configured with environment variables, system properties, and arguments as needed.
The nativeCompile
task of the GraalVM Native Image plugin is automatically configured to use the output of the processAot
task.
Processing Tests
The AOT engine can be applied to JUnit 5 tests that use Spring’s Test Context Framework.
Suitable tests are processed by the processTestAot
task to generate ApplicationContextInitializer
code.
As with application AOT processing, the BeanFactory
is fully prepared at build-time.
As with processAot
, the processTestAot
task is JavaExec
subclass and can be configured as needed to influence this processing.
The nativeTest
task of the GraalVM Native Image plugin is automatically configured to use the output of the processAot
and processTestAot
tasks.