预编译处理（Ahead-of-Time Processing）

Spring AOT 是一种在构建时分析你的应用并生成其优化版本的过程。要在 native image 中运行 Spring ApplicationContext，这是必需的步骤。

关于 Spring Boot 对 GraalVM Native Images 的支持，请参阅参考文档。

Spring Boot Maven 插件提供了可用于对应用和测试代码执行 AOT 处理的目标（goal）。

处理应用程序

要配置你的应用以使用此功能，请为 process-aot 目标添加一个 execution，如下例所示：

<plugin>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-maven-plugin</artifactId>
	<executions>
		<execution>
			<id>process-aot</id>
			<goals>
				<goal>process-aot</goal>
			</goals>
		</execution>
	</executions>
</plugin>

由于 BeanFactory 会在构建时完全准备好，条件也会被评估。这与常规 Spring Boot 应用在运行时的行为有重要区别。例如，如果你希望选择性启用或禁用某些功能，需要在构建时配置环境。因此，process-aot 目标与 run 目标共享许多属性。

使用 Native 配置文件（Profile）

如果你的项目以 spring-boot-starter-parent 作为 parent，可以使用 native 配置文件简化 native image 构建所需的步骤。

native 配置文件会进行如下配置：

当 Spring Boot Maven 插件应用于项目时，执行 process-aot。
适当设置，使 build-image 生成 native image。
为 Native Build Tools Maven Plugin 提供合理默认值，具体包括：
- 确保插件使用原始 classpath，而不是主 jar 文件（因其无法识别我们重新打包的 jar 格式）。
- 校验合适的 GraalVM 版本是否可用。
- 下载第三方 reachability metadata。

使用原始 classpath 意味着 native image 无法识别生成的 MANIFEST.MF。如果你需要在 native image 中读取 manifest 内容（例如获取应用实现版本），请将 classesDirectory 选项配置为常规 jar。

要使用 native 配置文件，代表应用的模块应定义如下两个插件，如下例所示：

<plugin>
	<groupId>org.graalvm.buildtools</groupId>
	<artifactId>native-maven-plugin</artifactId>
</plugin>
<plugin>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>

单个项目可通过命令行触发 native image 生成，方式包括 Cloud Native Buildpacks 或 Native Image Build Tools。

对于多模块项目，可自定义 native 配置文件以调用你偏好的方式。

若要在 package 阶段绑定 Cloud Native Buildpacks，请在多模块项目的根 POM 添加如下内容：

<profile>
	<id>native</id>
	<build>
		<pluginManagement>
			<plugins>
				<plugin>
					<groupId>org.springframework.boot</groupId>
					<artifactId>spring-boot-maven-plugin</artifactId>
					<executions>
						<execution>
							<id>build-image</id>
							<goals>
								<goal>build-image-no-fork</goal>
							</goals>
						</execution>
					</executions>
				</plugin>
			</plugins>
		</pluginManagement>
	</build>
</profile>

下例展示了 Native Build Tools 的配置方式：

<profile>
	<id>native</id>
	<build>
		<pluginManagement>
			<plugins>
				<plugin>
					<groupId>org.graalvm.buildtools</groupId>
					<artifactId>native-maven-plugin</artifactId>
					<executions>
						<execution>
							<id>build-image</id>
							<goals>
								<goal>compile-no-fork</goal>
							</goals>
						</execution>
					</executions>
				</plugin>
			</plugins>
		</pluginManagement>
	</build>
</profile>

完成上述配置后，你可以构建多模块项目，并在相关子模块中生成 native image，如下例所示：

$ mvn package -Pnative

“相关”子模块指的是代表 Spring Boot 应用的模块。此类模块必须如上所述定义 Native Build Tools 和 Spring Boot 插件。

`spring-boot:process-aot`

org.springframework.boot:spring-boot-maven-plugin:3.5.0

Invoke the AOT engine on the application.

Required parameters

Name Type Default

Name	Type	Default
classesDirectory	`File`	`${project.build.outputDirectory}`
generatedClasses	`File`	`${project.build.directory}/spring-aot/main/classes`
generatedResources	`File`	`${project.build.directory}/spring-aot/main/resources`
generatedSources	`File`	`${project.build.directory}/spring-aot/main/sources`

classesDirectory

File

${project.build.outputDirectory}

generatedClasses

File

${project.build.directory}/spring-aot/main/classes

generatedResources

File

${project.build.directory}/spring-aot/main/resources

generatedSources

File

${project.build.directory}/spring-aot/main/sources

Optional parameters

Name Type Default

Name	Type	Default
arguments	`String[]`
compilerArguments	`String`
excludeGroupIds	`String`
excludes	`List`
includes	`List`
jvmArguments	`String`
mainClass	`String`
profiles	`String[]`
skip	`boolean`	`false`
systemPropertyVariables	`Map`

String[]

String

String

List

List

String

String

String[]

boolean

false

systemPropertyVariables

Map

Parameter details

`arguments`

Application arguments that should be taken into account for AOT processing.

Name	`arguments`
Type	`java.lang.String[]`
Default value
User property
Since

Name

arguments

Type

java.lang.String[]

Default value

User property

Since

`classesDirectory`

Directory containing the classes and resource files that should be packaged into the archive.

Name	`classesDirectory`
Type	`java.io.File`
Default value	`${project.build.outputDirectory}`
User property
Since

Name

classesDirectory

Type

java.io.File

Default value

${project.build.outputDirectory}

User property

Since

`compilerArguments`

Arguments that should be provided to the AOT compile process. On command line, make sure to wrap multiple values between quotes.

Name	`compilerArguments`
Type	`java.lang.String`
Default value
User property	`spring-boot.aot.compilerArguments`
Since

Name

compilerArguments

Type

java.lang.String

Default value

User property

spring-boot.aot.compilerArguments

Since

`excludeGroupIds`

Comma separated list of groupId names to exclude (exact match).

Name	`excludeGroupIds`
Type	`java.lang.String`
Default value
User property	`spring-boot.excludeGroupIds`
Since	`1.1.0`

Name

excludeGroupIds

Type

java.lang.String

Default value

User property

spring-boot.excludeGroupIds

Since

1.1.0

`excludes`

Collection of artifact definitions to exclude. The Exclude element defines mandatory groupId and artifactId components and an optional classifier component. When configured as a property, values should be comma-separated with colon-separated components: groupId:artifactId,groupId:artifactId:classifier

Name	`excludes`
Type	`java.util.List`
Default value
User property	`spring-boot.excludes`
Since	`1.1.0`

Name

excludes

Type

java.util.List

Default value

User property

spring-boot.excludes

Since

1.1.0

`generatedClasses`

Directory containing the generated classes.

Name	`generatedClasses`
Type	`java.io.File`
Default value	`${project.build.directory}/spring-aot/main/classes`
User property
Since

Name

generatedClasses

Type

java.io.File

Default value

${project.build.directory}/spring-aot/main/classes

User property

Since

`generatedResources`

Directory containing the generated resources.

Name	`generatedResources`
Type	`java.io.File`
Default value	`${project.build.directory}/spring-aot/main/resources`
User property
Since

Name

generatedResources

Type

java.io.File

Default value

${project.build.directory}/spring-aot/main/resources

User property

Since

`generatedSources`

Directory containing the generated sources.

Name	`generatedSources`
Type	`java.io.File`
Default value	`${project.build.directory}/spring-aot/main/sources`
User property
Since

Name

generatedSources

Type

java.io.File

Default value

${project.build.directory}/spring-aot/main/sources

User property

Since

`includes`

Collection of artifact definitions to include. The Include element defines mandatory groupId and artifactId components and an optional classifier component. When configured as a property, values should be comma-separated with colon-separated components: groupId:artifactId,groupId:artifactId:classifier

Name	`includes`
Type	`java.util.List`
Default value
User property	`spring-boot.includes`
Since	`1.2.0`

Name

includes

Type

java.util.List

Default value

User property

spring-boot.includes

Since

1.2.0

`jvmArguments`

JVM arguments that should be associated with the AOT process. On command line, make sure to wrap multiple values between quotes.

Name	`jvmArguments`
Type	`java.lang.String`
Default value
User property	`spring-boot.aot.jvmArguments`
Since

Name

jvmArguments

Type

java.lang.String

Default value

User property

spring-boot.aot.jvmArguments

Since

`mainClass`

Name of the main class to use as the source for the AOT process. If not specified the first compiled class found that contains a 'main' method will be used.

Name	`mainClass`
Type	`java.lang.String`
Default value
User property	`spring-boot.aot.main-class`
Since

Name

mainClass

Type

java.lang.String

Default value

User property

spring-boot.aot.main-class

Since

`profiles`

Spring profiles to take into account for AOT processing.

Name	`profiles`
Type	`java.lang.String[]`
Default value
User property
Since

Name

profiles

Type

java.lang.String[]

Default value

User property

Since

`skip`

Skip the execution.

Name	`skip`
Type	`boolean`
Default value	`false`
User property	`spring-boot.aot.skip`
Since

Name

skip

Type

boolean

Default value

false

User property

spring-boot.aot.skip

Since

`systemPropertyVariables`

List of JVM system properties to pass to the AOT process.

Name	`systemPropertyVariables`
Type	`java.util.Map`
Default value
User property
Since

Name

systemPropertyVariables

Type

java.util.Map

Default value

User property

Since

处理测试

AOT 引擎可应用于使用 Spring Test Context Framework 的 JUnit 5 测试。这些测试会被 AOT 引擎处理，并在 native image 中执行。

与生产代码类似，spring-boot-starter-parent 定义了 nativeTest 配置文件，可简化在 native image 中执行测试所需的步骤。

nativeTest 配置文件会进行如下配置：

当 Spring Boot Maven 插件应用于项目时，执行 process-test-aot。
当 Native Build Tools Maven Plugin 应用于项目时，执行 test。该执行定义了合理默认值，具体包括：
- 确保插件使用原始 classpath，而不是主 jar 文件（因其无法识别我们重新打包的 jar 格式）。
- 校验合适的 GraalVM 版本是否可用。
- 下载第三方 reachability metadata。

要使用 nativeTest 配置文件，代表应用的模块应定义如下两个插件，如下例所示：

<plugin>
	<groupId>org.graalvm.buildtools</groupId>
	<artifactId>native-maven-plugin</artifactId>
</plugin>
<plugin>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>

为每个需要此功能的模块完成上述配置后，你可以构建多模块项目，并在相关子模块中以 native image 执行测试，如下例所示：

$ mvn test -PnativeTest

与应用 AOT 处理一样，BeanFactory 会在构建时完全准备好。

`spring-boot:process-test-aot`

org.springframework.boot:spring-boot-maven-plugin:3.5.0

Invoke the AOT engine on tests.

Required parameters

Name Type Default

Name	Type	Default
classesDirectory	`File`	`${project.build.outputDirectory}`
generatedClasses	`File`	`${project.build.directory}/spring-aot/main/classes`
generatedResources	`File`	`${project.build.directory}/spring-aot/test/resources`
generatedSources	`File`	`${project.build.directory}/spring-aot/test/sources`
generatedTestClasses	`File`	`${project.build.directory}/spring-aot/test/classes`
testClassesDirectory	`File`	`${project.build.testOutputDirectory}`

classesDirectory

File

${project.build.outputDirectory}

generatedClasses

File

${project.build.directory}/spring-aot/main/classes

generatedResources

File

${project.build.directory}/spring-aot/test/resources

generatedSources

File

${project.build.directory}/spring-aot/test/sources

generatedTestClasses

File

${project.build.directory}/spring-aot/test/classes

testClassesDirectory

File

${project.build.testOutputDirectory}

Optional parameters

Name Type Default

Name	Type	Default
compilerArguments	`String`
excludeGroupIds	`String`
excludes	`List`
includes	`List`
jvmArguments	`String`
skip	`boolean`	`false`
systemPropertyVariables	`Map`

String

String

List

List

String

boolean

false

systemPropertyVariables

Map

Parameter details

`classesDirectory`

Directory containing the classes and resource files that should be used to run the tests.

Name	`classesDirectory`
Type	`java.io.File`
Default value	`${project.build.outputDirectory}`
User property
Since

Name

classesDirectory

Type

java.io.File

Default value

${project.build.outputDirectory}

User property

Since

`compilerArguments`

Arguments that should be provided to the AOT compile process. On command line, make sure to wrap multiple values between quotes.

Name	`compilerArguments`
Type	`java.lang.String`
Default value
User property	`spring-boot.aot.compilerArguments`
Since

Name

compilerArguments

Type

java.lang.String

Default value

User property

spring-boot.aot.compilerArguments

Since

`excludeGroupIds`

Comma separated list of groupId names to exclude (exact match).

Name	`excludeGroupIds`
Type	`java.lang.String`
Default value
User property	`spring-boot.excludeGroupIds`
Since	`1.1.0`

Name

excludeGroupIds

Type

java.lang.String

Default value

User property

spring-boot.excludeGroupIds

Since

1.1.0

`excludes`

Name	`excludes`
Type	`java.util.List`
Default value
User property	`spring-boot.excludes`
Since	`1.1.0`

Name

excludes

Type

java.util.List

Default value

User property

spring-boot.excludes

Since

1.1.0

`generatedClasses`

Directory containing the generated test classes.

Name	`generatedClasses`
Type	`java.io.File`
Default value	`${project.build.directory}/spring-aot/main/classes`
User property
Since

Name

generatedClasses

Type

java.io.File

Default value

${project.build.directory}/spring-aot/main/classes

User property

Since

`generatedResources`

Directory containing the generated test resources.

Name	`generatedResources`
Type	`java.io.File`
Default value	`${project.build.directory}/spring-aot/test/resources`
User property
Since

Name

generatedResources

Type

java.io.File

Default value

${project.build.directory}/spring-aot/test/resources

User property

Since

`generatedSources`

Directory containing the generated sources.

Name	`generatedSources`
Type	`java.io.File`
Default value	`${project.build.directory}/spring-aot/test/sources`
User property
Since

Name

generatedSources

Type

java.io.File

Default value

${project.build.directory}/spring-aot/test/sources

User property

Since

`generatedTestClasses`

Directory containing the generated test classes.

Name	`generatedTestClasses`
Type	`java.io.File`
Default value	`${project.build.directory}/spring-aot/test/classes`
User property
Since

Name

generatedTestClasses

Type

java.io.File

Default value

${project.build.directory}/spring-aot/test/classes

User property

Since

`includes`

Name	`includes`
Type	`java.util.List`
Default value
User property	`spring-boot.includes`
Since	`1.2.0`

Name

includes

Type

java.util.List

Default value

User property

spring-boot.includes

Since

1.2.0

`jvmArguments`

JVM arguments that should be associated with the AOT process. On command line, make sure to wrap multiple values between quotes.

Name	`jvmArguments`
Type	`java.lang.String`
Default value
User property	`spring-boot.aot.jvmArguments`
Since

Name

jvmArguments

Type

java.lang.String

Default value

User property

spring-boot.aot.jvmArguments

Since

`skip`

Skip the execution.

Name	`skip`
Type	`boolean`
Default value	`false`
User property	`spring-boot.aot.skip`
Since

Name

skip

Type

boolean

Default value

false

User property

spring-boot.aot.skip

Since

`systemPropertyVariables`

List of JVM system properties to pass to the AOT process.

Name	`systemPropertyVariables`
Type	`java.util.Map`
Default value
User property
Since

Name

systemPropertyVariables

Type

java.util.Map

Default value

User property

Since

`testClassesDirectory`

Directory containing the classes and resource files that should be packaged into the archive.

Name	`testClassesDirectory`
Type	`java.io.File`
Default value	`${project.build.testOutputDirectory}`
User property
Since

Name

testClassesDirectory

Type

java.io.File

Default value

${project.build.testOutputDirectory}

User property

Since