Several enhancements with respect to CachingMetadataReaderFactory handling.

Added "clearCache()" method to CachingMetadataReaderFactory, for clearing the metadata cache once not needed anymore - in particular when the MetadataReaderFactory instance is long-lived. Also added "setMetadataReaderFactory" method to ClassPathScanningCandidateComponentProvider, analogous to ConfigurationClassPostProcessor.

Author: jhoeller

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

@@ -153,4 +153,10 @@ public void scan(String... basePackages) {
 		this.scanner.scan(basePackages);
 	}
 
+	@Override
+	protected void prepareRefresh() {
+		this.scanner.clearCache();
+		super.prepareRefresh();
+	}
+
 }

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

@@ -25,6 +25,7 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+
 import org.springframework.beans.factory.BeanDefinitionStoreException;
 import org.springframework.beans.factory.annotation.AnnotatedBeanDefinition;
 import org.springframework.beans.factory.config.BeanDefinition;
@@ -78,7 +79,8 @@ public class ClassPathScanningCandidateComponentProvider implements EnvironmentC
 
 	private ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
 
-	private MetadataReaderFactory metadataReaderFactory = new CachingMetadataReaderFactory(this.resourcePatternResolver);
+	private MetadataReaderFactory metadataReaderFactory =
+			new CachingMetadataReaderFactory(this.resourcePatternResolver);
 
 	private String resourcePattern = DEFAULT_RESOURCE_PATTERN;
 
@@ -120,6 +122,31 @@ public void setResourceLoader(ResourceLoader resourceLoader) {
 		this.metadataReaderFactory = new CachingMetadataReaderFactory(resourceLoader);
 	}
 
+	/**
+	 * Return the ResourceLoader that this component provider uses.
+	 */
+	public final ResourceLoader getResourceLoader() {
+		return this.resourcePatternResolver;
+	}
+
+	/**
+	 * Set the {@link MetadataReaderFactory} to use.
+	 * <p>Default is a {@link CachingMetadataReaderFactory} for the specified
+	 * {@linkplain #setResourceLoader resource loader}.
+	 * <p>Call this setter method <i>after</i> {@link #setResourceLoader} in order
+	 * for the given MetadataReaderFactory to override the default factory.
+	 */
+	public void setMetadataReaderFactory(MetadataReaderFactory metadataReaderFactory) {
+		this.metadataReaderFactory = metadataReaderFactory;
+	}
+
+	/**
+	 * Return the MetadataReaderFactory used by this component provider.
+	 */
+	public final MetadataReaderFactory getMetadataReaderFactory() {
+		return this.metadataReaderFactory;
+	}
+
 	/**
 	 * Set the Environment to use when resolving placeholders and evaluating
 	 * {@link Profile @Profile}-annotated component classes.
@@ -130,17 +157,10 @@ public void setEnvironment(Environment environment) {
 		this.environment = environment;
 	}
 
-	public Environment getEnvironment() {
+	public final Environment getEnvironment() {
 		return this.environment;
 	}
 
-	/**
-	 * Return the ResourceLoader that this component provider uses.
-	 */
-	public final ResourceLoader getResourceLoader() {
-		return this.resourcePatternResolver;
-	}
-
 	/**
 	 * Set the resource pattern to use when scanning the classpath.
 	 * This value will be appended to each base package name.
@@ -324,4 +344,14 @@ protected boolean isCandidateComponent(AnnotatedBeanDefinition beanDefinition) {
 		return (beanDefinition.getMetadata().isConcrete() && beanDefinition.getMetadata().isIndependent());
 	}
 
+
+	/**
+	 * Clear the underlying metadata cache, removing all cached class metadata.
+	 */
+	public void clearCache() {
+		if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) {
+			((CachingMetadataReaderFactory) this.metadataReaderFactory).clearCache();
+		}
+	}
+
 }

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

@@ -320,6 +320,10 @@ public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
 				singletonRegistry.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry());
 			}
 		}
+
+		if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) {
+			((CachingMetadataReaderFactory) this.metadataReaderFactory).clearCache();
+		}
 	}
 
 	/**

spring-core/src/main/java/org/springframework/core/type/classreading/CachingMetadataReaderFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2010 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -40,7 +40,7 @@ public class CachingMetadataReaderFactory extends SimpleMetadataReaderFactory {
 
 	private volatile int cacheLimit = DEFAULT_CACHE_LIMIT;
 
-	private final Map<Resource, MetadataReader> classReaderCache =
+	private final Map<Resource, MetadataReader> metadataReaderCache =
 			new LinkedHashMap<Resource, MetadataReader>(DEFAULT_CACHE_LIMIT, 0.75f, true) {
 				@Override
 				protected boolean removeEldestEntry(Map.Entry<Resource, MetadataReader> eldest) {
@@ -95,14 +95,23 @@ public MetadataReader getMetadataReader(Resource resource) throws IOException {
 		if (getCacheLimit() <= 0) {
 			return super.getMetadataReader(resource);
 		}
-		synchronized (this.classReaderCache) {
-			MetadataReader metadataReader = this.classReaderCache.get(resource);
+		synchronized (this.metadataReaderCache) {
+			MetadataReader metadataReader = this.metadataReaderCache.get(resource);
 			if (metadataReader == null) {
 				metadataReader = super.getMetadataReader(resource);
-				this.classReaderCache.put(resource, metadataReader);
+				this.metadataReaderCache.put(resource, metadataReader);
 			}
 			return metadataReader;
 		}
 	}
 
+	/**
+	 * Clear the entire MetadataReader cache, removing all cached class metadata.
+	 */
+	public void clearCache() {
+		synchronized (this.metadataReaderCache) {
+			this.metadataReaderCache.clear();
+		}
+	}
+
 }