OnWebApplicationCondition Class — spring-boot Architecture

Source Code

core/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/OnWebApplicationCondition.java lines 47–173

@Order(Ordered.HIGHEST_PRECEDENCE + 20)
class OnWebApplicationCondition extends FilteringSpringBootCondition {

	private static final String SERVLET_WEB_APPLICATION_CLASS = "org.springframework.web.context.support.GenericWebApplicationContext";

	private static final String REACTIVE_WEB_APPLICATION_CLASS = "org.springframework.web.reactive.HandlerResult";

	@Override
	protected @Nullable ConditionOutcome[] getOutcomes(@Nullable String[] autoConfigurationClasses,
			AutoConfigurationMetadata autoConfigurationMetadata) {
		@Nullable ConditionOutcome[] outcomes = new ConditionOutcome[autoConfigurationClasses.length];
		for (int i = 0; i < outcomes.length; i++) {
			String autoConfigurationClass = autoConfigurationClasses[i];
			if (autoConfigurationClass != null) {
				outcomes[i] = getOutcome(
						autoConfigurationMetadata.get(autoConfigurationClass, "ConditionalOnWebApplication"));
			}
		}
		return outcomes;
	}

	private @Nullable ConditionOutcome getOutcome(@Nullable String type) {
		if (type == null) {
			return null;
		}
		ConditionMessage.Builder message = ConditionMessage.forCondition(ConditionalOnWebApplication.class);
		ClassNameFilter missingClassFilter = ClassNameFilter.MISSING;
		if (ConditionalOnWebApplication.Type.SERVLET.name().equals(type)) {
			if (missingClassFilter.matches(SERVLET_WEB_APPLICATION_CLASS, getBeanClassLoader())) {
				return ConditionOutcome.noMatch(message.didNotFind("servlet web application classes").atAll());
			}
		}
		if (ConditionalOnWebApplication.Type.REACTIVE.name().equals(type)) {
			if (missingClassFilter.matches(REACTIVE_WEB_APPLICATION_CLASS, getBeanClassLoader())) {
				return ConditionOutcome.noMatch(message.didNotFind("reactive web application classes").atAll());
			}
		}
		if (missingClassFilter.matches(SERVLET_WEB_APPLICATION_CLASS, getBeanClassLoader())
				&& !ClassUtils.isPresent(REACTIVE_WEB_APPLICATION_CLASS, getBeanClassLoader())) {
			return ConditionOutcome.noMatch(message.didNotFind("reactive or servlet web application classes").atAll());
		}
		return null;
	}

	@Override
	public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
		boolean required = metadata.isAnnotated(ConditionalOnWebApplication.class.getName());
		ConditionOutcome outcome = isWebApplication(context, metadata, required);
		if (required && !outcome.isMatch()) {
			return ConditionOutcome.noMatch(outcome.getConditionMessage());
		}
		if (!required && outcome.isMatch()) {
			return ConditionOutcome.noMatch(outcome.getConditionMessage());
		}
		return ConditionOutcome.match(outcome.getConditionMessage());
	}

	private ConditionOutcome isWebApplication(ConditionContext context, AnnotatedTypeMetadata metadata,
			boolean required) {
		return switch (deduceType(metadata)) {
			case SERVLET -> isServletWebApplication(context);
			case REACTIVE -> isReactiveWebApplication(context);
			default -> isAnyWebApplication(context, required);
		};
	}

	private ConditionOutcome isAnyWebApplication(ConditionContext context, boolean required) {
		ConditionMessage.Builder message = ConditionMessage.forCondition(ConditionalOnWebApplication.class,
				required ? "(required)" : "");
		ConditionOutcome servletOutcome = isServletWebApplication(context);
		if (servletOutcome.isMatch() && required) {
			return new ConditionOutcome(servletOutcome.isMatch(), message.because(servletOutcome.getMessage()));
		}
		ConditionOutcome reactiveOutcome = isReactiveWebApplication(context);
		if (reactiveOutcome.isMatch() && required) {
			return new ConditionOutcome(reactiveOutcome.isMatch(), message.because(reactiveOutcome.getMessage()));
		}
		return new ConditionOutcome(servletOutcome.isMatch() || reactiveOutcome.isMatch(),
				message.because(servletOutcome.getMessage()).append("and").append(reactiveOutcome.getMessage()));
	}

	private ConditionOutcome isServletWebApplication(ConditionContext context) {
		ConditionMessage.Builder message = ConditionMessage.forCondition("");
		if (ClassNameFilter.MISSING.matches(SERVLET_WEB_APPLICATION_CLASS, context.getClassLoader())) {
			return ConditionOutcome.noMatch(message.didNotFind("servlet web application classes").atAll());
		}
		if (context.getBeanFactory() != null) {
			String[] scopes = context.getBeanFactory().getRegisteredScopeNames();
			if (ObjectUtils.containsElement(scopes, "session")) {
				return ConditionOutcome.match(message.foundExactly("'session' scope"));
			}
		}
		if (context.getEnvironment() instanceof ConfigurableWebEnvironment) {
			return ConditionOutcome.match(message.foundExactly("ConfigurableWebEnvironment"));
		}
		if (context.getResourceLoader() instanceof WebApplicationContext) {
			return ConditionOutcome.match(message.foundExactly("WebApplicationContext"));
		}
		return ConditionOutcome.noMatch(message.because("not a servlet web application"));
	}

	private ConditionOutcome isReactiveWebApplication(ConditionContext context) {
		ConditionMessage.Builder message = ConditionMessage.forCondition("");
		if (ClassNameFilter.MISSING.matches(REACTIVE_WEB_APPLICATION_CLASS, context.getClassLoader())) {
			return ConditionOutcome.noMatch(message.didNotFind("reactive web application classes").atAll());
		}
		if (context.getEnvironment() instanceof ConfigurableReactiveWebEnvironment) {
			return ConditionOutcome.match(message.foundExactly("ConfigurableReactiveWebEnvironment"));
		}
		if (context.getResourceLoader() instanceof ReactiveWebApplicationContext) {
			return ConditionOutcome.match(message.foundExactly("ReactiveWebApplicationContext"));
		}
		return ConditionOutcome.noMatch(message.because("not a reactive web application"));
	}

	private Type deduceType(AnnotatedTypeMetadata metadata) {
		Map<String, @Nullable Object> attributes = metadata
			.getAnnotationAttributes(ConditionalOnWebApplication.class.getName());
		if (attributes != null) {
			Object type = attributes.get("type");
			Assert.state(type != null, "'type' must not be null");
			return (Type) type;
		}
		return Type.ANY;
	}

}