@Configuration classes get processed according to their @Order (if applicable)

Issue: SPR-12657

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClassPostProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,10 +17,14 @@
 package org.springframework.context.annotation;
 
 import java.beans.PropertyDescriptor;
+import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
+import java.util.Comparator;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
@@ -264,7 +268,7 @@ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPo
 	 * {@link Configuration} classes.
 	 */
 	public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
-		Set<BeanDefinitionHolder> configCandidates = new LinkedHashSet<BeanDefinitionHolder>();
+		List<BeanDefinitionHolder> configCandidates = new ArrayList<BeanDefinitionHolder>();
 		String[] candidateNames = registry.getBeanDefinitionNames();
 
 		for (String beanName : candidateNames) {
@@ -285,6 +289,16 @@ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPo
 			return;
 		}
 
+		// Sort by previously determined @Order value, if applicable
+		Collections.sort(configCandidates, new Comparator<BeanDefinitionHolder>() {
+			@Override
+			public int compare(BeanDefinitionHolder bd1, BeanDefinitionHolder bd2) {
+				int i1 = ConfigurationClassUtils.getOrder(bd1.getBeanDefinition());
+				int i2 = ConfigurationClassUtils.getOrder(bd2.getBeanDefinition());
+				return (i1 < i2) ? -1 : (i1 > i2) ? 1 : 0;
+			}
+		});
+
 		// Detect any custom bean name generation strategy supplied through the enclosing application context
 		SingletonBeanRegistry singletonRegistry = null;
 		if (registry instanceof SingletonBeanRegistry) {
@@ -301,9 +315,10 @@ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPo
 				this.metadataReaderFactory, this.problemReporter, this.environment,
 				this.resourceLoader, this.componentScanBeanNameGenerator, registry);
 
+		Set<BeanDefinitionHolder> candidates = new LinkedHashSet<BeanDefinitionHolder>(configCandidates);
 		Set<ConfigurationClass> alreadyParsed = new HashSet<ConfigurationClass>(configCandidates.size());
 		do {
-			parser.parse(configCandidates);
+			parser.parse(candidates);
 			parser.validate();
 
 			Set<ConfigurationClass> configClasses = new LinkedHashSet<ConfigurationClass>(parser.getConfigurationClasses());
@@ -318,7 +333,7 @@ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPo
 			this.reader.loadBeanDefinitions(configClasses);
 			alreadyParsed.addAll(configClasses);
 
-			configCandidates.clear();
+			candidates.clear();
 			if (registry.getBeanDefinitionCount() > candidateNames.length) {
 				String[] newCandidateNames = registry.getBeanDefinitionNames();
 				Set<String> oldCandidateNames = new HashSet<String>(Arrays.asList(candidateNames));
@@ -331,14 +346,14 @@ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPo
 						BeanDefinition beanDef = registry.getBeanDefinition(candidateName);
 						if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory) &&
 								!alreadyParsedClasses.contains(beanDef.getBeanClassName())) {
-							configCandidates.add(new BeanDefinitionHolder(beanDef, candidateName));
+							candidates.add(new BeanDefinitionHolder(beanDef, candidateName));
 						}
 					}
 				}
 				candidateNames = newCandidateNames;
 			}
 		}
-		while (!configCandidates.isEmpty());
+		while (!candidates.isEmpty());
 
 		// Register the ImportRegistry as a bean in order to support ImportAware @Configuration classes
 		if (singletonRegistry != null) {

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClassUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,7 @@ package org.springframework.context.annotation;
 
 import java.io.IOException;
 import java.util.HashSet;
+import java.util.Map;
 import java.util.Set;
 
 import org.apache.commons.logging.Log;
@@ -27,6 +28,9 @@ import org.springframework.beans.factory.annotation.AnnotatedBeanDefinition;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.support.AbstractBeanDefinition;
 import org.springframework.core.Conventions;
+import org.springframework.core.Ordered;
+import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.core.annotation.Order;
 import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.core.type.StandardAnnotationMetadata;
 import org.springframework.core.type.classreading.MetadataReader;
@@ -49,6 +53,9 @@ abstract class ConfigurationClassUtils {
 	private static final String CONFIGURATION_CLASS_ATTRIBUTE =
 			Conventions.getQualifiedAttributeName(ConfigurationClassPostProcessor.class, "configurationClass");
 
+	private static final String ORDER_ATTRIBUTE =
+			Conventions.getQualifiedAttributeName(ConfigurationClassPostProcessor.class, "order");
+
 
 	private static final Log logger = LogFactory.getLog(ConfigurationClassUtils.class);
 
@@ -101,6 +108,11 @@ abstract class ConfigurationClassUtils {
 			}
 		}
 
+		Map<String, Object> orderAttributes = metadata.getAnnotationAttributes(Order.class.getName());
+		if (orderAttributes != null) {
+			beanDef.setAttribute(ORDER_ATTRIBUTE, orderAttributes.get(AnnotationUtils.VALUE));
+		}
+
 		if (isFullConfigurationCandidate(metadata)) {
 			beanDef.setAttribute(CONFIGURATION_CLASS_ATTRIBUTE, CONFIGURATION_CLASS_FULL);
 			return true;
@@ -173,4 +185,16 @@ abstract class ConfigurationClassUtils {
 		return CONFIGURATION_CLASS_LITE.equals(beanDef.getAttribute(CONFIGURATION_CLASS_ATTRIBUTE));
 	}
 
+	/**
+	 * Determine the order for the given configuration class bean definition,
+	 * as set by {@link #checkConfigurationClassCandidate}.
+	 * @param beanDef the bean definition to check
+	 * @return the {@link @Order} annotation value on the configuration class,
+	 * or {@link Ordered#LOWEST_PRECEDENCE} if none declared
+	 */
+	public static int getOrder(BeanDefinition beanDef) {
+		Integer order = (Integer) beanDef.getAttribute(ORDER_ATTRIBUTE);
+		return (order != null ? order : Ordered.LOWEST_PRECEDENCE);
+	}
+
 }

spring-context/src/test/java/org/springframework/context/annotation/ConfigurationClassPostProcessorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,6 +28,7 @@ import org.junit.Test;
 import org.springframework.aop.scope.ScopedObject;
 import org.springframework.aop.scope.ScopedProxyUtils;
 import org.springframework.beans.factory.BeanCreationException;
+import org.springframework.beans.factory.BeanDefinitionStoreException;
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -40,6 +41,7 @@ import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.componentscan.simple.SimpleComponent;
+import org.springframework.core.annotation.Order;
 import org.springframework.core.env.StandardEnvironment;
 import org.springframework.core.io.DescriptiveResource;
 import org.springframework.stereotype.Component;
@@ -271,6 +273,35 @@ public class ConfigurationClassPostProcessorTests {
 		beanFactory.getBean("bar", TestBean.class);
 	}
 
+	@Test
+	public void postProcessorFailsOnImplicitOverrideIfOverridingIsNotAllowed() {
+		RootBeanDefinition rbd = new RootBeanDefinition(TestBean.class);
+		rbd.setResource(new DescriptiveResource("XML or something"));
+		beanFactory.registerBeanDefinition("bar", rbd);
+		beanFactory.registerBeanDefinition("config", new RootBeanDefinition(SingletonBeanConfig.class));
+		beanFactory.setAllowBeanDefinitionOverriding(false);
+		ConfigurationClassPostProcessor pp = new ConfigurationClassPostProcessor();
+		try {
+			pp.postProcessBeanFactory(beanFactory);
+			fail("Should have thrown BeanDefinitionStoreException");
+		}
+		catch (BeanDefinitionStoreException ex) {
+			assertTrue(ex.getMessage().contains("bar"));
+			assertTrue(ex.getMessage().contains("SingletonBeanConfig"));
+			assertTrue(ex.getMessage().contains(TestBean.class.getName()));
+		}
+	}
+
+	@Test
+	public void configurationClassesProcessedInCorrectOrder() {
+		beanFactory.registerBeanDefinition("config1", new RootBeanDefinition(OverridingSingletonBeanConfig.class));
+		beanFactory.registerBeanDefinition("config2", new RootBeanDefinition(SingletonBeanConfig.class));
+		ConfigurationClassPostProcessor pp = new ConfigurationClassPostProcessor();
+		pp.postProcessBeanFactory(beanFactory);
+		assertTrue(beanFactory.getBean(Foo.class) instanceof ExtendedFoo);
+		beanFactory.getBean(Bar.class);
+	}
+
 	@Test
 	public void scopedProxyTargetMarkedAsNonAutowireCandidate() {
 		AutowiredAnnotationBeanPostProcessor bpp = new AutowiredAnnotationBeanPostProcessor();
@@ -485,6 +516,7 @@ public class ConfigurationClassPostProcessorTests {
 	// -------------------------------------------------------------------------
 
 	@Configuration
+	@Order(1)
 	static class SingletonBeanConfig {
 
 		public @Bean
@@ -498,9 +530,27 @@ public class ConfigurationClassPostProcessorTests {
 		}
 	}
 
+	@Configuration
+	@Order(2)
+	static class OverridingSingletonBeanConfig {
+
+		public @Bean
+		ExtendedFoo foo() {
+			return new ExtendedFoo();
+		}
+
+		public @Bean
+		Bar bar() {
+			return new Bar(foo());
+		}
+	}
+
 	static class Foo {
 	}
 
+	static class ExtendedFoo extends Foo {
+	}
+
 	static class Bar {
 
 		final Foo foo;