SPR-7308

SPR-7736
+ clarify storage of null values

org.springframework.context.support/src/test/java/org/springframework/cache/config/AbstractAnnotationTest.java

@@ -16,8 +16,7 @@
 
 package org.springframework.cache.config;
 
-import static org.junit.Assert.assertNotSame;
-import static org.junit.Assert.assertSame;
+import static org.junit.Assert.*;
 
 import org.junit.Before;
 import org.junit.Test;
@@ -26,6 +25,7 @@ import org.springframework.context.support.ClassPathXmlApplicationContext;
 
 /**
  * Abstract annotation test (containing several reusable methods).
+ * 
  * @author Costin Leau
  */
 public abstract class AbstractAnnotationTest {
@@ -72,7 +72,8 @@ public abstract class AbstractAnnotationTest {
 		assertSame(r3, r4);
 	}
 
-	public void testConditionalExpression(CacheableService service) throws Exception {
+	public void testConditionalExpression(CacheableService service)
+			throws Exception {
 		Object r1 = service.conditional(4);
 		Object r2 = service.conditional(4);
 
@@ -96,6 +97,16 @@ public abstract class AbstractAnnotationTest {
 		assertNotSame(r3, r4);
 	}
 
+	public void testNullValue(CacheableService service) throws Exception {
+		Object key = new Object();
+		assertNull(service.nullValue(key));
+		int nr = service.nullInvocations().intValue();
+		assertNull(service.nullValue(key));
+		assertEquals(nr, service.nullInvocations().intValue());
+		assertNull(service.nullValue(new Object()));
+		assertEquals(nr + 1, service.nullInvocations().intValue());
+	}
+
 	@Test
 	public void testCacheable() throws Exception {
 		testCacheable(cs);
@@ -126,4 +137,22 @@ public abstract class AbstractAnnotationTest {
 		testInvalidate(ccs);
 	}
 
+	@Test
+	public void testNullValue() throws Exception {
+		testNullValue(cs);
+	}
+
+	@Test
+	public void testClassNullValue() throws Exception {
+		Object key = new Object();
+		assertNull(ccs.nullValue(key));
+		int nr = ccs.nullInvocations().intValue();
+		assertNull(ccs.nullValue(key));
+		assertEquals(nr, ccs.nullInvocations().intValue());
+		assertNull(ccs.nullValue(new Object()));
+		// the check method is also cached
+		assertEquals(nr, ccs.nullInvocations().intValue());
+		assertEquals(nr + 1, AnnotatedClassCacheableService.nullInvocations
+				.intValue());
+	}
 }

org.springframework.context.support/src/test/java/org/springframework/cache/config/AnnotatedClassCacheableService.java

@@ -27,7 +27,8 @@ import org.springframework.cache.annotation.Cacheable;
 @Cacheable("default")
 public class AnnotatedClassCacheableService implements CacheableService {
 
-	private AtomicLong counter = new AtomicLong();
+	private final AtomicLong counter = new AtomicLong();
+	public static final AtomicLong nullInvocations = new AtomicLong();
 
 	public Object cache(Object arg1) {
 		return counter.getAndIncrement();
@@ -45,4 +46,13 @@ public class AnnotatedClassCacheableService implements CacheableService {
 	public Object key(Object arg1, Object arg2) {
 		return counter.getAndIncrement();
 	}
+
+	public Object nullValue(Object arg1) {
+		nullInvocations.incrementAndGet();
+		return null;
+	}
+
+	public Number nullInvocations() {
+		return nullInvocations.get();
+	}
 }

org.springframework.context.support/src/test/java/org/springframework/cache/config/CacheableService.java

@@ -16,6 +16,7 @@
 
 package org.springframework.cache.config;
 
+
 /**
  * Basic service interface.
  * 
@@ -31,4 +32,8 @@ public interface CacheableService<T> {
 
 	T key(Object arg1, Object arg2);
 
+	T nullValue(Object arg1);
+
+	Number nullInvocations();
+
 }

org.springframework.context.support/src/test/java/org/springframework/cache/config/DefaultCacheableService.java

@@ -21,7 +21,6 @@ import java.util.concurrent.atomic.AtomicLong;
 import org.springframework.cache.annotation.CacheEvict;
 import org.springframework.cache.annotation.Cacheable;
 
-
 /**
  * Simple cacheable service
  * 
@@ -29,7 +28,8 @@ import org.springframework.cache.annotation.Cacheable;
  */
 public class DefaultCacheableService implements CacheableService<Long> {
 
-	private AtomicLong counter = new AtomicLong();
+	private final AtomicLong counter = new AtomicLong();
+	private final AtomicLong nullInvocations = new AtomicLong();
 
 	@Cacheable("default")
 	public Long cache(Object arg1) {
@@ -49,4 +49,14 @@ public class DefaultCacheableService implements CacheableService<Long> {
 	public Long key(Object arg1, Object arg2) {
 		return counter.getAndIncrement();
 	}
+
+	@Cacheable("default")
+	public Long nullValue(Object arg1) {
+		nullInvocations.incrementAndGet();
+		return null;
+	}
+
+	public Number nullInvocations() {
+		return nullInvocations.get();
+	}
 }