Create CGLIB proxy in case of no target interfaces (just introductions)

Closes gh-31304

Author: jhoeller

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -59,7 +59,7 @@ public class DefaultAopProxyFactory implements AopProxyFactory, Serializable {
 
 	@Override
 	public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException {
-		if (config.isOptimize() || config.isProxyTargetClass() || hasNoUserSuppliedProxyInterfaces(config)) {
+		if (config.isOptimize() || config.isProxyTargetClass() || !hasTargetInterfaces(config)) {
 			Class<?> targetClass = config.getTargetClass();
 			if (targetClass == null) {
 				throw new AopConfigException("TargetSource cannot determine target class: " +
@@ -75,14 +75,14 @@ public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException
 		}
 	}
 
-	/**
-	 * Determine whether the supplied {@link AdvisedSupport} has only the
-	 * {@link org.springframework.aop.SpringProxy} interface specified
-	 * (or no proxy interfaces specified at all).
-	 */
-	private boolean hasNoUserSuppliedProxyInterfaces(AdvisedSupport config) {
-		Class<?>[] ifcs = config.getProxiedInterfaces();
-		return (ifcs.length == 0 || (ifcs.length == 1 && SpringProxy.class.isAssignableFrom(ifcs[0])));
+	private boolean hasTargetInterfaces(AdvisedSupport config) {
+		Class<?> targetClass = config.getTargetClass();
+		for (Class<?> ifc : config.getProxiedInterfaces()) {
+			if (targetClass != null ? ifc.isAssignableFrom(targetClass) : !SpringProxy.class.isAssignableFrom(ifc)) {
+				return true;
+			}
+		}
+		return false;
 	}
 
 }

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

@@ -189,25 +189,22 @@ public int compareTo(Object arg0) {
 			}
 		}
 		TestBeanSubclass raw = new TestBeanSubclass();
-		ProxyFactory factory = new ProxyFactory(raw);
-		//System.out.println("Proxied interfaces are " + StringUtils.arrayToDelimitedString(factory.getProxiedInterfaces(), ","));
-		assertThat(factory.getProxiedInterfaces()).as("Found correct number of interfaces").hasSize(5);
-		ITestBean tb = (ITestBean) factory.getProxy();
+		ProxyFactory pf = new ProxyFactory(raw);
+		assertThat(pf.getProxiedInterfaces()).as("Found correct number of interfaces").hasSize(5);
+		ITestBean tb = (ITestBean) pf.getProxy();
 		assertThat(tb).as("Picked up secondary interface").isInstanceOf(IOther.class);
 		raw.setAge(25);
 		assertThat(tb.getAge()).isEqualTo(raw.getAge());
 
+		Class<?>[] oldProxiedInterfaces = pf.getProxiedInterfaces();
 		long t = 555555L;
 		TimestampIntroductionInterceptor ti = new TimestampIntroductionInterceptor(t);
+		pf.addAdvisor(0, new DefaultIntroductionAdvisor(ti, TimeStamped.class));
 
-		Class<?>[] oldProxiedInterfaces = factory.getProxiedInterfaces();
-
-		factory.addAdvisor(0, new DefaultIntroductionAdvisor(ti, TimeStamped.class));
-
-		Class<?>[] newProxiedInterfaces = factory.getProxiedInterfaces();
+		Class<?>[] newProxiedInterfaces = pf.getProxiedInterfaces();
 		assertThat(newProxiedInterfaces).as("Advisor proxies one more interface after introduction").hasSize(oldProxiedInterfaces.length + 1);
 
-		TimeStamped ts = (TimeStamped) factory.getProxy();
+		TimeStamped ts = (TimeStamped) pf.getProxy();
 		assertThat(ts.getTimeStamp()).isEqualTo(t);
 		// Shouldn't fail;
 		((IOther) ts).absquatulate();
@@ -224,26 +221,26 @@ public Object invoke(MethodInvocation invocation) {
 
 		NopInterceptor di = new NopInterceptor();
 		NopInterceptor diUnused = new NopInterceptor();
-		ProxyFactory factory = new ProxyFactory(new TestBean());
-		factory.addAdvice(0, di);
-		assertThat(factory.getProxy()).isInstanceOf(ITestBean.class);
-		assertThat(factory.adviceIncluded(di)).isTrue();
-		assertThat(factory.adviceIncluded(diUnused)).isFalse();
-		assertThat(factory.countAdvicesOfType(NopInterceptor.class)).isEqualTo(1);
-		assertThat(factory.countAdvicesOfType(MyInterceptor.class)).isEqualTo(0);
-
-		factory.addAdvice(0, diUnused);
-		assertThat(factory.adviceIncluded(diUnused)).isTrue();
-		assertThat(factory.countAdvicesOfType(NopInterceptor.class)).isEqualTo(2);
+		ProxyFactory pf = new ProxyFactory(new TestBean());
+		pf.addAdvice(0, di);
+		assertThat(pf.getProxy()).isInstanceOf(ITestBean.class);
+		assertThat(pf.adviceIncluded(di)).isTrue();
+		assertThat(pf.adviceIncluded(diUnused)).isFalse();
+		assertThat(pf.countAdvicesOfType(NopInterceptor.class)).isEqualTo(1);
+		assertThat(pf.countAdvicesOfType(MyInterceptor.class)).isEqualTo(0);
+
+		pf.addAdvice(0, diUnused);
+		assertThat(pf.adviceIncluded(diUnused)).isTrue();
+		assertThat(pf.countAdvicesOfType(NopInterceptor.class)).isEqualTo(2);
 	}
 
 	@Test
 	void sealedInterfaceExclusion() {
 		// String implements ConstantDesc on JDK 12+, sealed as of JDK 17
-		ProxyFactory factory = new ProxyFactory("");
+		ProxyFactory pf = new ProxyFactory("");
 		NopInterceptor di = new NopInterceptor();
-		factory.addAdvice(0, di);
-		Object proxy = factory.getProxy();
+		pf.addAdvice(0, di);
+		Object proxy = pf.getProxy();
 		assertThat(proxy).isInstanceOf(CharSequence.class);
 	}
 
@@ -330,6 +327,19 @@ void proxyTargetClassWithConcreteClassAsTarget() {
 		assertThat(AopProxyUtils.ultimateTargetClass(proxy2)).isEqualTo(TestBean.class);
 	}
 
+	@Test
+	void proxyTargetClassWithIntroducedInterface() {
+		ProxyFactory pf = new ProxyFactory();
+		pf.setTargetClass(MyDate.class);
+		TimestampIntroductionInterceptor ti = new TimestampIntroductionInterceptor(0L);
+		pf.addAdvisor(0, new DefaultIntroductionAdvisor(ti, TimeStamped.class));
+		Object proxy = pf.getProxy();
+		assertThat(AopUtils.isCglibProxy(proxy)).as("Proxy is a CGLIB proxy").isTrue();
+		assertThat(proxy).isInstanceOf(MyDate.class);
+		assertThat(proxy).isInstanceOf(TimeStamped.class);
+		assertThat(AopProxyUtils.ultimateTargetClass(proxy)).isEqualTo(MyDate.class);
+	}
+
 	@Test
 	void interfaceProxiesCanBeOrderedThroughAnnotations() {
 		Object proxy1 = new ProxyFactory(new A()).getProxy();