ResourceCondition Class — spring-boot Architecture

Source Code

core/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/ResourceCondition.java lines 38–95

public abstract class ResourceCondition extends SpringBootCondition {

	private final String name;

	private final String property;

	private final String[] resourceLocations;

	/**
	 * Create a new condition.
	 * @param name the name of the component
	 * @param property the configuration property
	 * @param resourceLocations default location(s) where the configuration file can be
	 * found if the configuration key is not specified
	 * @since 2.0.0
	 */
	protected ResourceCondition(String name, String property, String... resourceLocations) {
		this.name = name;
		this.property = property;
		this.resourceLocations = resourceLocations;
	}

	@Override
	public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
		if (context.getEnvironment().containsProperty(this.property)) {
			return ConditionOutcome.match(startConditionMessage().foundExactly("property " + this.property));
		}
		return getResourceOutcome(context, metadata);
	}

	/**
	 * Check if one of the default resource locations actually exists.
	 * @param context the condition context
	 * @param metadata the annotation metadata
	 * @return the condition outcome
	 */
	protected ConditionOutcome getResourceOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
		List<String> found = new ArrayList<>();
		for (String location : this.resourceLocations) {
			Resource resource = context.getResourceLoader().getResource(location);
			if (resource != null && resource.exists()) {
				found.add(location);
			}
		}
		if (found.isEmpty()) {
			ConditionMessage message = startConditionMessage().didNotFind("resource", "resources")
				.items(Style.QUOTE, Arrays.asList(this.resourceLocations));
			return ConditionOutcome.noMatch(message);
		}
		ConditionMessage message = startConditionMessage().found("resource", "resources").items(Style.QUOTE, found);
		return ConditionOutcome.match(message);
	}

	protected final Builder startConditionMessage() {
		return ConditionMessage.forCondition("ResourceCondition", "(" + this.name + ")");
	}

}