OnJavaCondition Class — spring-boot Architecture

Source Code

core/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/OnJavaCondition.java lines 39–80

@Order(Ordered.HIGHEST_PRECEDENCE + 20)
class OnJavaCondition extends SpringBootCondition {

	private static final JavaVersion JVM_VERSION = JavaVersion.getJavaVersion();

	@Override
	public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
		Map<String, @Nullable Object> attributes = metadata.getAnnotationAttributes(ConditionalOnJava.class.getName());
		Assert.state(attributes != null, "'attributes' must not be null");
		Range range = (Range) attributes.get("range");
		Assert.state(range != null, "'range' must not be null");
		JavaVersion version = (JavaVersion) attributes.get("value");
		Assert.state(version != null, "'version' must not be null");
		return getMatchOutcome(range, JVM_VERSION, version);
	}

	protected ConditionOutcome getMatchOutcome(Range range, JavaVersion runningVersion, JavaVersion version) {
		boolean match = isWithin(runningVersion, range, version);
		String expected = String.format((range != Range.EQUAL_OR_NEWER) ? "(older than %s)" : "(%s or newer)", version);
		ConditionMessage message = ConditionMessage.forCondition(ConditionalOnJava.class, expected)
			.foundExactly(runningVersion);
		return new ConditionOutcome(match, message);
	}

	/**
	 * Determines if the {@code runningVersion} is within the specified range of versions.
	 * @param runningVersion the current version.
	 * @param range the range
	 * @param version the bounds of the range
	 * @return if this version is within the specified range
	 */
	private boolean isWithin(JavaVersion runningVersion, Range range, JavaVersion version) {
		if (range == Range.EQUAL_OR_NEWER) {
			return runningVersion.isEqualOrNewerThan(version);
		}
		if (range == Range.OLDER_THAN) {
			return runningVersion.isOlderThan(version);
		}
		throw new IllegalStateException("Unknown range " + range);
	}

}