StandardOutcomesResolver Class — spring-boot Architecture

Source Code

core/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/OnClassCondition.java lines 183–251

	private static final class StandardOutcomesResolver implements OutcomesResolver {

		private final @Nullable String[] autoConfigurationClasses;

		private final int start;

		private final int end;

		private final AutoConfigurationMetadata autoConfigurationMetadata;

		private final ClassLoader beanClassLoader;

		private StandardOutcomesResolver(@Nullable String[] autoConfigurationClasses, int start, int end,
				AutoConfigurationMetadata autoConfigurationMetadata, ClassLoader beanClassLoader) {
			this.autoConfigurationClasses = autoConfigurationClasses;
			this.start = start;
			this.end = end;
			this.autoConfigurationMetadata = autoConfigurationMetadata;
			this.beanClassLoader = beanClassLoader;
		}

		@Override
		public @Nullable ConditionOutcome[] resolveOutcomes() {
			return getOutcomes(this.autoConfigurationClasses, this.start, this.end, this.autoConfigurationMetadata);
		}

		private @Nullable ConditionOutcome[] getOutcomes(@Nullable String[] autoConfigurationClasses, int start,
				int end, AutoConfigurationMetadata autoConfigurationMetadata) {
			@Nullable ConditionOutcome[] outcomes = new ConditionOutcome[end - start];
			for (int i = start; i < end; i++) {
				String autoConfigurationClass = autoConfigurationClasses[i];
				if (autoConfigurationClass != null) {
					String candidates = autoConfigurationMetadata.get(autoConfigurationClass, "ConditionalOnClass");
					if (candidates != null) {
						outcomes[i - start] = getOutcome(candidates);
					}
				}
			}
			return outcomes;
		}

		private @Nullable ConditionOutcome getOutcome(String candidates) {
			try {
				if (!candidates.contains(",")) {
					return getOutcome(candidates, this.beanClassLoader);
				}
				for (String candidate : StringUtils.commaDelimitedListToStringArray(candidates)) {
					ConditionOutcome outcome = getOutcome(candidate, this.beanClassLoader);
					if (outcome != null) {
						return outcome;
					}
				}
			}
			catch (Exception ex) {
				// We'll get another chance later
			}
			return null;
		}

		private @Nullable ConditionOutcome getOutcome(String className, ClassLoader classLoader) {
			if (ClassNameFilter.MISSING.matches(className, classLoader)) {
				return ConditionOutcome.noMatch(ConditionMessage.forCondition(ConditionalOnClass.class)
					.didNotFind("required class")
					.items(Style.QUOTE, className));
			}
			return null;
		}

	}