Expose ResolvableType in NoSuchBeanDefinitionException

This commit improves NoSuchBeanDefinitionException to expose a full
ResolvableType rather than a raw class if a lookup by type failed. This
allows to know more about the underlying type and is typically useful
when a collection or map is required as the relevant generic type is the
actual bean that wasn't found.

Issue: SPR-14831

spring-beans/src/main/java/org/springframework/beans/factory/NoSuchBeanDefinitionException.java

@@ -17,6 +17,7 @@
 package org.springframework.beans.factory;
 
 import org.springframework.beans.BeansException;
+import org.springframework.core.ResolvableType;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
 
@@ -27,6 +28,7 @@ import org.springframework.util.StringUtils;
  *
  * @author Rod Johnson
  * @author Juergen Hoeller
+ * @author Stephane Nicoll
  * @see BeanFactory#getBean(String)
  * @see BeanFactory#getBean(Class)
  * @see NoUniqueBeanDefinitionException
@@ -38,7 +40,7 @@ public class NoSuchBeanDefinitionException extends BeansException {
 	private String beanName;
 
 	/** Required type of the missing bean */
-	private Class<?> beanType;
+	private ResolvableType beanResolvableType;
 
 
 	/**
@@ -66,7 +68,7 @@ public class NoSuchBeanDefinitionException extends BeansException {
 	 */
 	public NoSuchBeanDefinitionException(Class<?> type) {
 		super("No qualifying bean of type [" + type.getName() + "] is defined");
-		this.beanType = type;
+		this.beanResolvableType = ResolvableType.forClass(type);
 	}
 
 	/**
@@ -76,7 +78,7 @@ public class NoSuchBeanDefinitionException extends BeansException {
 	 */
 	public NoSuchBeanDefinitionException(Class<?> type, String message) {
 		super("No qualifying bean of type [" + ClassUtils.getQualifiedName(type) + "] is defined: " + message);
-		this.beanType = type;
+		this.beanResolvableType = ResolvableType.forClass(type);
 	}
 
 	/**
@@ -84,13 +86,34 @@ public class NoSuchBeanDefinitionException extends BeansException {
 	 * @param type required type of the missing bean
 	 * @param dependencyDescription a description of the originating dependency
 	 * @param message detailed message describing the problem
+	 * @deprecated as of Spring 5.0, in favor of {@link #NoSuchBeanDefinitionException(ResolvableType, String)}
 	 */
+	@Deprecated
 	public NoSuchBeanDefinitionException(Class<?> type, String dependencyDescription, String message) {
+		this(ResolvableType.forClass(type), dependencyDescription, message);
+	}
+
+	/**
+	 * Create a new {@code NoSuchBeanDefinitionException}.
+	 * @param resolvableType required type of the missing bean
+	 * @param message detailed message describing the problem
+	 */
+	public NoSuchBeanDefinitionException(ResolvableType resolvableType, String message) {
+		this(resolvableType, resolvableType.toString(), message);
+	}
+
+	/**
+	 * Create a new {@code NoSuchBeanDefinitionException}.
+	 * @param resolvableType required type of the missing bean
+	 * @param dependencyDescription a description of the originating dependency
+	 * @param message detailed message describing the problem
+	 */
+	private NoSuchBeanDefinitionException(ResolvableType resolvableType, String dependencyDescription, String message) {
 		super("No qualifying bean" + (!StringUtils.hasLength(dependencyDescription) ?
-				" of type [" + ClassUtils.getQualifiedName(type) + "]" : "") + " found for dependency" +
-				(StringUtils.hasLength(dependencyDescription) ? " [" + dependencyDescription + "]" : "") +
-				": " + message);
-		this.beanType = type;
+				" of type [" + ClassUtils.getQualifiedName(resolvableType.getRawClass()) + "]" : "") +
+				" found for dependency" + (StringUtils.hasLength(dependencyDescription) ? " [" +
+				dependencyDescription + "]" : "") + ": " + message);
+		this.beanResolvableType = resolvableType;
 	}
 
 
@@ -101,11 +124,19 @@ public class NoSuchBeanDefinitionException extends BeansException {
 		return this.beanName;
 	}
 
+	/**
+	 * Return the required {@link ResolvableType} of the missing bean, if it was a lookup
+	 * <em>by type</em> that failed.
+	 */
+	public ResolvableType getBeanResolvableType() {
+		return this.beanResolvableType;
+	}
+
 	/**
 	 * Return the required type of the missing bean, if it was a lookup <em>by type</em> that failed.
 	 */
 	public Class<?> getBeanType() {
-		return this.beanType;
+		return this.beanResolvableType.getRawClass();
 	}
 
 	/**

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

@@ -1081,7 +1081,7 @@ public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFacto
 			Map<String, Object> matchingBeans = findAutowireCandidates(beanName, type, descriptor);
 			if (matchingBeans.isEmpty()) {
 				if (descriptor.isRequired()) {
-					raiseNoMatchingBeanFound(type, descriptor.getResolvableType().toString(), descriptor);
+					raiseNoMatchingBeanFound(type, descriptor.getResolvableType(), descriptor);
 				}
 				return null;
 			}
@@ -1444,11 +1444,11 @@ public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFacto
 	 * for an unresolvable dependency.
 	 */
 	private void raiseNoMatchingBeanFound(
-			Class<?> type, String dependencyDescription, DependencyDescriptor descriptor) throws BeansException {
+			Class<?> type, ResolvableType resolvableType, DependencyDescriptor descriptor) throws BeansException {
 
 		checkBeanNotOfRequiredType(type, descriptor);
 
-		throw new NoSuchBeanDefinitionException(type, dependencyDescription,
+		throw new NoSuchBeanDefinitionException(resolvableType,
 				"expected at least 1 bean which qualifies as autowire candidate. " +
 				"Dependency annotations: " + ObjectUtils.nullSafeToString(descriptor.getAnnotations()));
 	}