Refactor and deprecate TransactionAspectUtils

TransactionAspectUtils contains a number of methods useful in
retrieving a bean by type+qualifier. These methods are functionally
general-purpose save for the hard coding of PlatformTransactionManager
class literals throughout.

This commit generifies these methods and moves them into
BeanFactoryUtils primarily in anticipation of their use by async method
execution interceptors and aspects when performing lookups for qualified
executor beans e.g. via @Async("qualifier").

The public API of TransactionAspectUtils remains backward compatible;
all methods within have been deprecated, and all calls to those methods
throughout the framework refactored to use the new BeanFactoryUtils
variants instead.

spring-beans/src/main/java/org/springframework/beans/factory/BeanFactoryUtils.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.
@@ -16,6 +16,8 @@
 
 package org.springframework.beans.factory;
 
+import java.lang.reflect.Method;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.LinkedHashMap;
@@ -23,7 +25,14 @@ import java.util.List;
 import java.util.Map;
 
 import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.beans.factory.config.BeanDefinition;
+import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.beans.factory.support.AbstractBeanDefinition;
+import org.springframework.beans.factory.support.AutowireCandidateQualifier;
+import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.util.Assert;
+import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 
 /**
@@ -37,6 +46,7 @@ import org.springframework.util.StringUtils;
  *
  * @author Rod Johnson
  * @author Juergen Hoeller
+ * @author Chris Beams
  * @since 04.07.2003
  */
 public abstract class BeanFactoryUtils {
@@ -431,4 +441,102 @@ public abstract class BeanFactoryUtils {
 		}
 	}
 
+	/**
+	 * Obtain a bean of type {@code T} from the given {@code BeanFactory} declaring a
+	 * qualifier (e.g. via {@code <qualifier>} or {@code @Qualifier}) matching the given
+	 * qualifier, or having a bean name matching the given qualifier.
+	 * @param bf the BeanFactory to get the target bean from
+	 * @param beanType the type of bean to retrieve
+	 * @param qualifier the qualifier for selecting between multiple bean matches
+	 * @return the matching bean of type {@code T} (never {@code null})
+	 * @throws IllegalStateException if no matching bean of type {@code T} found
+	 * @since 3.2
+	 */
+	public static <T> T qualifiedBeanOfType(BeanFactory beanFactory, Class<T> beanType, String qualifier) {
+		if (beanFactory instanceof ConfigurableListableBeanFactory) {
+			// Full qualifier matching supported.
+			return qualifiedBeanOfType((ConfigurableListableBeanFactory) beanFactory, beanType, qualifier);
+		}
+		else if (beanFactory.containsBean(qualifier)) {
+			// Fallback: target bean at least found by bean name.
+			return beanFactory.getBean(qualifier, beanType);
+		}
+		else {
+			throw new IllegalStateException("No matching " + beanType.getSimpleName() +
+					" bean found for bean name '" + qualifier +
+					"'! (Note: Qualifier matching not supported because given " +
+					"BeanFactory does not implement ConfigurableListableBeanFactory.)");
+		}
+	}
+
+	/**
+	 * Obtain a bean of type {@code T} from the given {@code BeanFactory} declaring a
+	 * qualifier (e.g. {@code <qualifier>} or {@code @Qualifier}) matching the given
+	 * qualifier
+	 * @param bf the BeanFactory to get the target bean from
+	 * @param beanType the type of bean to retrieve
+	 * @param qualifier the qualifier for selecting between multiple bean matches
+	 * @return the matching bean of type {@code T} (never {@code null})
+	 * @throws IllegalStateException if no matching bean of type {@code T} found
+	 */
+	private static <T> T qualifiedBeanOfType(ConfigurableListableBeanFactory bf, Class<T> beanType, String qualifier) {
+		Map<String, T> candidateBeans = BeanFactoryUtils.beansOfTypeIncludingAncestors(bf, beanType);
+		T matchingBean = null;
+		for (String beanName : candidateBeans.keySet()) {
+			if (isQualifierMatch(qualifier, beanName, bf)) {
+				if (matchingBean != null) {
+					throw new IllegalStateException("No unique " + beanType.getSimpleName() +
+							" bean found for qualifier '" + qualifier + "'");
+				}
+				matchingBean = candidateBeans.get(beanName);
+			}
+		}
+		if (matchingBean != null) {
+			return matchingBean;
+		}
+		else {
+			throw new IllegalStateException("No matching " + beanType.getSimpleName() +
+					" bean found for qualifier '" + qualifier + "' - neither qualifier " +
+					"match nor bean name match!");
+		}
+	}
+
+	/**
+	 * Check whether the named bean declares a qualifier of the given name.
+	 * @param qualifier the qualifier to match
+	 * @param beanName the name of the candidate bean
+	 * @param bf the {@code BeanFactory} from which to retrieve the named bean
+	 * @return {@code true} if either the bean definition (in the XML case)
+	 * or the bean's factory method (in the {@code @Bean} case) defines a matching
+	 * qualifier value (through {@code <qualifier>} or {@code @Qualifier})
+	 */
+	private static boolean isQualifierMatch(String qualifier, String beanName, ConfigurableListableBeanFactory bf) {
+		if (bf.containsBean(beanName)) {
+			try {
+				BeanDefinition bd = bf.getMergedBeanDefinition(beanName);
+				if (bd instanceof AbstractBeanDefinition) {
+					AbstractBeanDefinition abd = (AbstractBeanDefinition) bd;
+					AutowireCandidateQualifier candidate = abd.getQualifier(Qualifier.class.getName());
+					if ((candidate != null && qualifier.equals(candidate.getAttribute(AutowireCandidateQualifier.VALUE_KEY))) ||
+							qualifier.equals(beanName) || ObjectUtils.containsElement(bf.getAliases(beanName), qualifier)) {
+						return true;
+					}
+				}
+				if (bd instanceof RootBeanDefinition) {
+					Method factoryMethod = ((RootBeanDefinition) bd).getResolvedFactoryMethod();
+					if (factoryMethod != null) {
+						Qualifier targetAnnotation = factoryMethod.getAnnotation(Qualifier.class);
+						if (targetAnnotation != null && qualifier.equals(targetAnnotation.value())) {
+							return true;
+						}
+					}
+				}
+			}
+			catch (NoSuchBeanDefinitionException ex) {
+				// ignore - can't compare qualifiers for a manually registered singleton object
+			}
+		}
+		return false;
+	}
+
 }