SimpleAliasRegistry logs info message for alias overriding

Issue: SPR-16871

(cherry picked from commit 74fcdea)

Author: jhoeller

spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractAutowireCapableBeanFactory.java

@@ -39,6 +39,8 @@
 import java.util.concurrent.ConcurrentMap;
 import java.util.function.Supplier;
 
+import org.apache.commons.logging.Log;
+
 import org.springframework.beans.BeanUtils;
 import org.springframework.beans.BeanWrapper;
 import org.springframework.beans.BeanWrapperImpl;
@@ -1870,6 +1872,14 @@ protected void clearSingletonCache() {
 		}
 	}
 
+	/**
+	 * Expose the logger to collaborating delegates.
+	 * @since 5.0.7
+	 */
+	Log getLogger() {
+		return logger;
+	}
+
 
 	/**
 	 * Special DependencyDescriptor variant for Spring's good old autowire="byType" mode.

spring-beans/src/main/java/org/springframework/beans/factory/support/ConstructorResolver.java

@@ -32,6 +32,8 @@
 import java.util.Map;
 import java.util.Set;
 
+import org.apache.commons.logging.Log;
+
 import org.springframework.beans.BeanMetadataElement;
 import org.springframework.beans.BeanWrapper;
 import org.springframework.beans.BeanWrapperImpl;
@@ -78,13 +80,16 @@ class ConstructorResolver {
 
 	private final AbstractAutowireCapableBeanFactory beanFactory;
 
+	private final Log logger;
+
 
 	/**
 	 * Create a new ConstructorResolver for the given factory and instantiation strategy.
 	 * @param beanFactory the BeanFactory to work with
 	 */
 	public ConstructorResolver(AbstractAutowireCapableBeanFactory beanFactory) {
 		this.beanFactory = beanFactory;
+		this.logger = beanFactory.getLogger();
 	}
 
 
@@ -193,9 +198,8 @@ public BeanWrapper autowireConstructor(final String beanName, final RootBeanDefi
 								getUserDeclaredConstructor(candidate), autowiring);
 					}
 					catch (UnsatisfiedDependencyException ex) {
-						if (this.beanFactory.logger.isTraceEnabled()) {
-							this.beanFactory.logger.trace(
-									"Ignoring constructor [" + candidate + "] of bean '" + beanName + "': " + ex);
+						if (logger.isTraceEnabled()) {
+							logger.trace("Ignoring constructor [" + candidate + "] of bean '" + beanName + "': " + ex);
 						}
 						// Swallow and try next constructor.
 						if (causes == null) {
@@ -471,9 +475,8 @@ public BeanWrapper instantiateUsingFactoryMethod(
 									beanName, mbd, resolvedValues, bw, paramTypes, paramNames, candidate, autowiring);
 						}
 						catch (UnsatisfiedDependencyException ex) {
-							if (this.beanFactory.logger.isTraceEnabled()) {
-								this.beanFactory.logger.trace("Ignoring factory method [" + candidate +
-										"] of bean '" + beanName + "': " + ex);
+							if (logger.isTraceEnabled()) {
+								logger.trace("Ignoring factory method [" + candidate + "] of bean '" + beanName + "': " + ex);
 							}
 							// Swallow and try next overloaded factory method.
 							if (causes == null) {
@@ -733,8 +736,8 @@ private ArgumentsHolder createArgumentArray(
 
 		for (String autowiredBeanName : autowiredBeanNames) {
 			this.beanFactory.registerDependentBean(autowiredBeanName, beanName);
-			if (this.beanFactory.logger.isDebugEnabled()) {
-				this.beanFactory.logger.debug("Autowiring by type from bean name '" + beanName +
+			if (logger.isDebugEnabled()) {
+				logger.debug("Autowiring by type from bean name '" + beanName +
 						"' via " + (executable instanceof Constructor ? "constructor" : "factory method") +
 						" to bean named '" + autowiredBeanName + "'");
 			}

spring-beans/src/main/java/org/springframework/beans/factory/support/DefaultSingletonBeanRegistry.java

@@ -26,9 +26,6 @@
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
-
 import org.springframework.beans.factory.BeanCreationException;
 import org.springframework.beans.factory.BeanCreationNotAllowedException;
 import org.springframework.beans.factory.BeanCurrentlyInCreationException;
@@ -73,9 +70,6 @@
  */
 public class DefaultSingletonBeanRegistry extends SimpleAliasRegistry implements SingletonBeanRegistry {
 
-	/** Logger available to subclasses */
-	protected final Log logger = LogFactory.getLog(getClass());
-
 	/** Cache of singleton objects: bean name --> bean instance */
 	private final Map<String, Object> singletonObjects = new ConcurrentHashMap<>(256);
 

spring-core/src/main/java/org/springframework/core/SimpleAliasRegistry.java

@@ -22,6 +22,9 @@
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 import org.springframework.util.StringValueResolver;
@@ -37,6 +40,9 @@
  */
 public class SimpleAliasRegistry implements AliasRegistry {
 
+	/** Logger available to subclasses */
+	protected final Log logger = LogFactory.getLog(getClass());
+
 	/** Map from alias to canonical name */
 	private final Map<String, String> aliasMap = new ConcurrentHashMap<>(16);
 
@@ -48,6 +54,9 @@ public void registerAlias(String name, String alias) {
 		synchronized (this.aliasMap) {
 			if (alias.equals(name)) {
 				this.aliasMap.remove(alias);
+				if (logger.isDebugEnabled()) {
+					logger.debug("Alias definition '" + alias + "' ignored since it points to same name");
+				}
 			}
 			else {
 				String registeredName = this.aliasMap.get(alias);
@@ -57,12 +66,19 @@ public void registerAlias(String name, String alias) {
 						return;
 					}
 					if (!allowAliasOverriding()) {
-						throw new IllegalStateException("Cannot register alias '" + alias + "' for name '" +
+						throw new IllegalStateException("Cannot define alias '" + alias + "' for name '" +
 								name + "': It is already registered for name '" + registeredName + "'.");
 					}
+					if (this.logger.isInfoEnabled()) {
+						logger.info("Overriding alias '" + alias + "' definition for registered name '" +
+								registeredName + "' with new target name '" + name + "'");
+					}
 				}
 				checkForAliasCircle(name, alias);
 				this.aliasMap.put(alias, name);
+				if (logger.isDebugEnabled()) {
+					logger.debug("Alias definition '" + alias + "' registered for name '" + name + "'");
+				}
 			}
 		}
 	}