Merge branch '6.2.x'

spring-aop/src/main/java/org/springframework/aop/framework/DefaultAopProxyFactory.java

@@ -60,11 +60,12 @@ public class DefaultAopProxyFactory implements AopProxyFactory, Serializable {
 	public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException {
 		if (config.isOptimize() || config.isProxyTargetClass() || !config.hasUserSuppliedInterfaces()) {
 			Class<?> targetClass = config.getTargetClass();
-			if (targetClass == null) {
+			if (targetClass == null && config.getProxiedInterfaces().length == 0) {
 				throw new AopConfigException("TargetSource cannot determine target class: " +
 						"Either an interface or a target is required for proxy creation.");
 			}
-			if (targetClass.isInterface() || Proxy.isProxyClass(targetClass) || ClassUtils.isLambdaClass(targetClass)) {
+			if (targetClass == null || targetClass.isInterface() ||
+					Proxy.isProxyClass(targetClass) || ClassUtils.isLambdaClass(targetClass)) {
 				return new JdkDynamicAopProxy(config);
 			}
 			return new ObjenesisCglibAopProxy(config);

spring-aop/src/test/java/org/springframework/aop/framework/ProxyFactoryTests.java

@@ -340,6 +340,18 @@ class ProxyFactoryTests {
 		assertThat(AopProxyUtils.ultimateTargetClass(proxy)).isEqualTo(MyDate.class);
 	}
 
+	@Test
+	void proxyInterfaceInCaseOfIntroducedInterfaceOnly() {
+		ProxyFactory pf = new ProxyFactory();
+		pf.addInterface(TimeStamped.class);
+		TimestampIntroductionInterceptor ti = new TimestampIntroductionInterceptor(0L);
+		pf.addAdvisor(new DefaultIntroductionAdvisor(ti, TimeStamped.class));
+		Object proxy = pf.getProxy();
+		assertThat(AopUtils.isJdkDynamicProxy(proxy)).as("Proxy is a JDK proxy").isTrue();
+		assertThat(proxy).isInstanceOf(TimeStamped.class);
+		assertThat(AopProxyUtils.ultimateTargetClass(proxy)).isEqualTo(proxy.getClass());
+	}
+
 	@Test
 	void proxyInterfaceInCaseOfNonTargetInterface() {
 		ProxyFactory pf = new ProxyFactory();

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

@@ -991,6 +991,8 @@ public abstract class AbstractAutowireCapableBeanFactory extends AbstractBeanFac
 	 */
 	@Nullable
 	private FactoryBean<?> getSingletonFactoryBeanForTypeCheck(String beanName, RootBeanDefinition mbd) {
+		this.singletonLock.lock();
+		try {
 			BeanWrapper bw = this.factoryBeanInstanceCache.get(beanName);
 			if (bw != null) {
 				return (FactoryBean<?>) bw.getWrappedInstance();
@@ -1040,6 +1042,10 @@ public abstract class AbstractAutowireCapableBeanFactory extends AbstractBeanFac
 
 			return getFactoryBean(beanName, instance);
 		}
+		finally {
+			this.singletonLock.unlock();
+		}
+	}
 
 	/**
 	 * Obtain a "shortcut" non-singleton FactoryBean instance to use for a

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

@@ -76,6 +76,9 @@ public class DefaultSingletonBeanRegistry extends SimpleAliasRegistry implements
 	private static final int SUPPRESSED_EXCEPTIONS_LIMIT = 100;
 
 
+	/** Common lock for singleton creation. */
+	final Lock singletonLock = new ReentrantLock();
+
 	/** Cache of singleton objects: bean name to bean instance. */
 	private final Map<String, Object> singletonObjects = new ConcurrentHashMap<>(256);
 
@@ -91,8 +94,6 @@ public class DefaultSingletonBeanRegistry extends SimpleAliasRegistry implements
 	/** Set of registered singletons, containing the bean names in registration order. */
 	private final Set<String> registeredSingletons = Collections.synchronizedSet(new LinkedHashSet<>(256));
 
-	private final Lock singletonLock = new ReentrantLock();
-
 	/** Names of beans that are currently in creation. */
 	private final Set<String> singletonsCurrentlyInCreation = ConcurrentHashMap.newKeySet(16);
 

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

@@ -118,6 +118,8 @@ public abstract class FactoryBeanRegistrySupport extends DefaultSingletonBeanReg
 	 */
 	protected Object getObjectFromFactoryBean(FactoryBean<?> factory, String beanName, boolean shouldPostProcess) {
 		if (factory.isSingleton() && containsSingleton(beanName)) {
+			this.singletonLock.lock();
+			try {
 				Object object = this.factoryBeanObjectCache.get(beanName);
 				if (object == null) {
 					object = doGetObjectFromFactoryBean(factory, beanName);
@@ -152,6 +154,10 @@ public abstract class FactoryBeanRegistrySupport extends DefaultSingletonBeanReg
 				}
 				return object;
 			}
+			finally {
+				this.singletonLock.unlock();
+			}
+		}
 		else {
 			Object object = doGetObjectFromFactoryBean(factory, beanName);
 			if (shouldPostProcess) {