com.gitlab.spacetrucker.modularspringcontexts.module.ModularSpringContextsDynamicScopeBeanDefinitionParser Maven / Gradle / Ivy

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Small utility library to allow modular definitions of Spring ApplicationContexts.
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package com.gitlab.spacetrucker.modularspringcontexts.module;

import java.text.MessageFormat;

import org.springframework.beans.BeansException;
import org.springframework.beans.MutablePropertyValues;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.support.AbstractBeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionValidationException;
import org.springframework.beans.factory.support.GenericBeanDefinition;
import org.springframework.beans.factory.xml.AbstractBeanDefinitionParser;
import org.springframework.beans.factory.xml.ParserContext;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ConfigurableApplicationContext;
import org.w3c.dom.Element;

import com.gitlab.spacetrucker.modularspringcontexts.SingletonBeanImportFactoryBean;

/**
 * Bean definition parser that is able to determine the scope of the imported
 * bean and therefore define the scope of the imported bean in the importing
 * {@link ApplicationContext} as it was originally defined.
 * 
 * This bean definition parser is also able to check whether a bean to be
 * imported is marked as exported in the {@code ApplicationContext} from which
 * it is imported. A bean definition can be marked as exported via a meta
 * attribute named {@code exported} with value {@code true}. A value of false or
 * the absence of this meta attribute will define the bean as not exported. The
 * import of non-exported beans is not possible.
 */
public class ModularSpringContextsDynamicScopeBeanDefinitionParser extends AbstractBeanDefinitionParser
		implements ApplicationContextAware {

	private BeanFactory applicationContextBeanFactory;
	private boolean checkVisibility;

	/**
	 * Creates a bean definition for the bean to be imported by requesting
	 * required informations from the bean factory of the application context
	 * from which the bean is imported.
	 * 
	 * @throws BeanDefinitionValidationException
	 *             if this instance is configured to
	 *             {@link #setCheckVisibility(boolean) check visibility} and the
	 *             imported bean is not visible.
	 */
	@Override
	protected AbstractBeanDefinition parseInternal(Element element, ParserContext parserContext) {
		String sourceModule = element.getAttribute("sourceModule");
		String sourceBean = element.getAttribute("sourceBean");
		if (sourceBean == null || sourceBean.length() == 0) {
			sourceBean = element.getAttribute("id");
		}
		if (checkVisibility && !isVisible(sourceModule, sourceBean)) {
			throw new BeanDefinitionValidationException(
					MessageFormat.format("Bean {0} of module {1} is not exported.", sourceBean, sourceModule));
		}
		GenericBeanDefinition beanDefinition = new GenericBeanDefinition();
		beanDefinition.setBeanClass(SingletonBeanImportFactoryBean.class);
		MutablePropertyValues propertyValues = createPropertyValues(sourceModule, sourceBean);
		beanDefinition.setPropertyValues(propertyValues);
		beanDefinition.setScope(defineScope(sourceModule, sourceBean));
		return beanDefinition;
	}

	private boolean isVisible(String sourceModule, String sourceBean) {
		BeanDefinition definition = getBeanDefinition(sourceModule, sourceBean);
		Object exportedAttribute = definition.getAttribute(ModularSpringContextsConstants.EXPORTED_META_ATTRIBUTE);
		if (exportedAttribute instanceof String) {
			return Boolean.parseBoolean((String) exportedAttribute);
		}
		return false;
	}

	private String defineScope(String sourceModule, String sourceBean) {
		BeanDefinition beanDefinition = getBeanDefinition(sourceModule, sourceBean);
		return beanDefinition.getScope();
	}

	private BeanDefinition getBeanDefinition(String sourceModule, String sourceBean) {
		ConfigurableApplicationContext sourceModuleBean = applicationContextBeanFactory.getBean(sourceModule,
				ConfigurableApplicationContext.class);
		BeanDefinition beanDefinition = sourceModuleBean.getBeanFactory().getMergedBeanDefinition(sourceBean);
		return beanDefinition;
	}

	private MutablePropertyValues createPropertyValues(String sourceModule, String sourceBean) {
		MutablePropertyValues propertyValues = new MutablePropertyValues();
		propertyValues.addPropertyValue("sourceModuleName", sourceModule);
		propertyValues.addPropertyValue("sourceBeanName", sourceBean);
		return propertyValues;
	}

	public void setApplicationContextBeanFactory(BeanFactory applicationContextBeanFactory) {
		this.applicationContextBeanFactory = applicationContextBeanFactory;
	}

	public void setCheckVisibility(boolean checkVisibility) {
		this.checkVisibility = checkVisibility;
	}

	@Override
	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
		setApplicationContextBeanFactory(applicationContext);
	}

}