Infer AnnotationAttributes method return types

 - Drop 'expectedType' parameter from #getClass and #getEnum methods and
   rely on compiler inference based on type of assigned variable, e.g.

     public @interface Example {
         Color color();
         Class<? extends UserType> userType();
         int order() default 0;
     }

     AnnotationAttributes example =
        AnnotationUtils.getAnnotationAttributes(Example.class, true, true);

     Color color = example.getEnum("color");
     Class<? extends UserType> userType = example.getClass("userType");

   or in cases where there is no variable assignment (and thus no
   inference possible), use explicit generic type, e.g.

     bean.setColor(example.<Color>getEnum("color"));

 - Rename #get{Int=>Number} and update return type from int to
   <N extends Number>, allowing invocations such as:

     int order = example.getNumber("order");

These changes reduce the overall number of methods exposed by
AnnotationAttributes, while at the same time providing comprehensive
access to all possible annotation attribute types -- that is, instead of
requiring explicit #getInt, #getFloat, #getDouble methods, the
single #getNumber method is capabable of handling them all, and without
any casting required. And the obvious additional benefit is more concise
invocation as no redundant 'expectedType' parameters are required.

Author: cbeams

org.springframework.context/src/main/java/org/springframework/cache/annotation/ProxyCachingConfiguration.java

@@ -44,7 +44,7 @@ public BeanFactoryCacheOperationSourceAdvisor cacheAdvisor() {
 			new BeanFactoryCacheOperationSourceAdvisor();
 		advisor.setCacheOperationSource(cacheOperationSource());
 		advisor.setAdvice(cacheInterceptor());
-		advisor.setOrder(this.enableCaching.getInt("order"));
+		advisor.setOrder(this.enableCaching.<Integer>getNumber("order"));
 		return advisor;
 	}
 

org.springframework.context/src/main/java/org/springframework/context/annotation/AdviceModeImportSelector.java

@@ -73,8 +73,7 @@ public final String[] selectImports(AnnotationMetadata importingClassMetadata) {
 				"@%s is not present on importing class '%s' as expected",
 				annoType.getSimpleName(), importingClassMetadata.getClassName()));
 
-		AdviceMode adviceMode =
-				attributes.getEnum(this.getAdviceModeAttributeName(), AdviceMode.class);
+		AdviceMode adviceMode = attributes.getEnum(this.getAdviceModeAttributeName());
 
 		String[] imports = selectImports(adviceMode);
 		Assert.notNull(imports, String.format("Unknown AdviceMode: '%s'", adviceMode));

org.springframework.context/src/main/java/org/springframework/context/annotation/AnnotationConfigUtils.java

@@ -232,8 +232,8 @@ static void processCommonDefinitionAnnotations(AnnotatedBeanDefinition abd) {
 		}
 		if (abd instanceof AbstractBeanDefinition) {
 			if (metadata.isAnnotated(Role.class.getName())) {
-				((AbstractBeanDefinition)abd).setRole(
-						attributesFor(metadata, Role.class).getInt("value"));
+				int role = attributesFor(metadata, Role.class).getNumber("value");
+				((AbstractBeanDefinition)abd).setRole(role);
 			}
 		}
 	}

org.springframework.context/src/main/java/org/springframework/context/annotation/AnnotationScopeMetadataResolver.java

@@ -81,7 +81,7 @@ public ScopeMetadata resolveScopeMetadata(BeanDefinition definition) {
 					attributesFor(annDef.getMetadata(), this.scopeAnnotationType);
 			if (attributes != null) {
 				metadata.setScopeName(attributes.getString("value"));
-				ScopedProxyMode proxyMode = attributes.getEnum("proxyMode", ScopedProxyMode.class);
+				ScopedProxyMode proxyMode = attributes.getEnum("proxyMode");
 				if (proxyMode == null || proxyMode == ScopedProxyMode.DEFAULT) {
 					proxyMode = this.defaultProxyMode;
 				}

org.springframework.context/src/main/java/org/springframework/context/annotation/ComponentScanAnnotationParser.java

@@ -70,15 +70,15 @@ public Set<BeanDefinitionHolder> parse(AnnotationAttributes componentScan) {
 		Assert.notNull(this.resourceLoader, "ResourceLoader must not be null");
 		scanner.setResourceLoader(this.resourceLoader);
 
-		scanner.setBeanNameGenerator(BeanUtils.instantiateClass(
-				componentScan.getClass("nameGenerator", BeanNameGenerator.class)));
+		Class<? extends BeanNameGenerator> generatorClass = componentScan.getClass("nameGenerator");
+		scanner.setBeanNameGenerator(BeanUtils.instantiateClass(generatorClass));
 
-		ScopedProxyMode scopedProxyMode = componentScan.getEnum("scopedProxy", ScopedProxyMode.class);
+		ScopedProxyMode scopedProxyMode = componentScan.getEnum("scopedProxy");
 		if (scopedProxyMode != ScopedProxyMode.DEFAULT) {
 			scanner.setScopedProxyMode(scopedProxyMode);
 		} else {
-			scanner.setScopeMetadataResolver(BeanUtils.instantiateClass(
-					componentScan.getClass("scopeResolver", ScopeMetadataResolver.class)));
+			Class<? extends ScopeMetadataResolver> resolverClass = componentScan.getClass("scopeResolver");
+			scanner.setScopeMetadataResolver(BeanUtils.instantiateClass(resolverClass));
 		}
 
 		scanner.setResourcePattern(componentScan.getString("resourcePattern"));
@@ -118,7 +118,7 @@ public Set<BeanDefinitionHolder> parse(AnnotationAttributes componentScan) {
 
 	private List<TypeFilter> typeFiltersFor(AnnotationAttributes filterAttributes) {
 		List<TypeFilter> typeFilters = new ArrayList<TypeFilter>();
-		FilterType filterType = filterAttributes.getEnum("type", FilterType.class);
+		FilterType filterType = filterAttributes.getEnum("type");
 
 		for (Class<?> filterClass : filterAttributes.getClassArray("value")) {
 			switch (filterType) {

org.springframework.context/src/main/java/org/springframework/context/annotation/ConfigurationClassBeanDefinitionReader.java

@@ -198,7 +198,7 @@ private void loadBeanDefinitionsForBeanMethod(BeanMethod beanMethod) {
 		// consider role
 		AnnotationAttributes role = attributesFor(metadata, Role.class);
 		if (role != null) {
-			beanDef.setRole(role.getInt("value"));
+			beanDef.setRole(role.<Integer>getNumber("value"));
 		}
 
 		// consider name and any aliases
@@ -246,7 +246,7 @@ else if (configClass.getMetadata().isAnnotated(Lazy.class.getName())){
 			}
 		}
 
-		Autowire autowire = bean.getEnum("autowire", Autowire.class);
+		Autowire autowire = bean.getEnum("autowire");
 		if (autowire.isAutowire()) {
 			beanDef.setAutowireMode(autowire.value());
 		}
@@ -266,7 +266,7 @@ else if (configClass.getMetadata().isAnnotated(Lazy.class.getName())){
 		AnnotationAttributes scope = attributesFor(metadata, Scope.class);
 		if (scope != null) {
 			beanDef.setScope(scope.getString("value"));
-			proxyMode = scope.getEnum("proxyMode", ScopedProxyMode.class);
+			proxyMode = scope.getEnum("proxyMode");
 			if (proxyMode == ScopedProxyMode.DEFAULT) {
 				proxyMode = ScopedProxyMode.NO;
 			}

org.springframework.context/src/main/java/org/springframework/context/annotation/ConfigurationClassParser.java

@@ -216,8 +216,7 @@ protected void doProcessConfigurationClass(ConfigurationClass configClass, Annot
 		if (metadata.isAnnotated(ImportResource.class.getName())) {
 			AnnotationAttributes importResource = attributesFor(metadata, ImportResource.class);
 			String[] resources = importResource.getStringArray("value");
-			Class<? extends BeanDefinitionReader> readerClass =
-					importResource.getClass("reader", BeanDefinitionReader.class);
+			Class<? extends BeanDefinitionReader> readerClass = importResource.getClass("reader");
 			for (String resource : resources) {
 				configClass.addImportedResource(resource, readerClass);
 			}

org.springframework.context/src/main/java/org/springframework/context/annotation/LoadTimeWeavingConfiguration.java

@@ -18,8 +18,6 @@
 
 import static org.springframework.context.weaving.AspectJWeavingEnabler.ASPECTJ_AOP_XML_RESOURCE;
 
-import java.util.Map;
-
 import org.springframework.beans.factory.BeanClassLoaderAware;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.config.BeanDefinition;
@@ -80,7 +78,8 @@ public LoadTimeWeaver loadTimeWeaver() {
 			loadTimeWeaver = new DefaultContextLoadTimeWeaver(this.beanClassLoader);
 		}
 
-		switch (this.enableLTW.getEnum("aspectjWeaving", AspectJWeaving.class)) {
+		AspectJWeaving aspectJWeaving = this.enableLTW.getEnum("aspectjWeaving");
+		switch (aspectJWeaving) {
 			case DISABLED:
 				// AJ weaving is disabled -> do nothing
 				break;

org.springframework.context/src/main/java/org/springframework/scheduling/annotation/ProxyAsyncConfiguration.java

@@ -46,7 +46,7 @@ public AsyncAnnotationBeanPostProcessor asyncAdvisor() {
 
 		AsyncAnnotationBeanPostProcessor bpp = new AsyncAnnotationBeanPostProcessor();
 
-		Class<? extends Annotation> customAsyncAnnotation = enableAsync.getClass("annotation", Annotation.class);
+		Class<? extends Annotation> customAsyncAnnotation = enableAsync.getClass("annotation");
 		if (customAsyncAnnotation != AnnotationUtils.getDefaultValue(EnableAsync.class, "annotation")) {
 			bpp.setAsyncAnnotationType(customAsyncAnnotation);
 		}
@@ -56,8 +56,7 @@ public AsyncAnnotationBeanPostProcessor asyncAdvisor() {
 		}
 
 		bpp.setProxyTargetClass(this.enableAsync.getBoolean("proxyTargetClass"));
-
-		bpp.setOrder(this.enableAsync.getInt("order"));
+		bpp.setOrder(this.enableAsync.<Integer>getNumber("order"));
 
 		return bpp;
 	}

org.springframework.core/src/main/java/org/springframework/core/annotation/AnnotationAttributes.java

@@ -92,16 +92,18 @@ public boolean getBoolean(String attributeName) {
 		return doGet(attributeName, Boolean.class);
 	}
 
-	public int getInt(String attributeName) {
-		return doGet(attributeName, Integer.class);
+	@SuppressWarnings("unchecked")
+	public <N extends Number> N getNumber(String attributeName) {
+		return (N) doGet(attributeName, Integer.class);
 	}
 
-	public <E extends Enum<?>> E getEnum(String attributeName, Class<E> enumType) {
-		return doGet(attributeName, enumType);
+	@SuppressWarnings("unchecked")
+	public <E extends Enum<?>> E getEnum(String attributeName) {
+		return (E) doGet(attributeName, Enum.class);
 	}
 
 	@SuppressWarnings("unchecked")
-	public <T> Class<? extends T> getClass(String attributeName, Class<T> expectedType) {
+	public <T> Class<? extends T> getClass(String attributeName) {
 		return (Class<T>)doGet(attributeName, Class.class);
 	}
 

org.springframework.core/src/test/java/org/springframework/core/annotation/AnnotationAttributesTests.java

@@ -55,11 +55,11 @@ public void testTypeSafeAttributeAccess() {
 		assertThat(a.getStringArray("names"), equalTo(new String[] { "dave", "frank", "hal" }));
 		assertThat(a.getBoolean("bool1"), equalTo(true));
 		assertThat(a.getBoolean("bool2"), equalTo(false));
-		assertThat(a.getEnum("color", Color.class), equalTo(Color.RED));
-		assertTrue(a.getClass("clazz", Number.class).equals(Integer.class));
+		assertThat(a.<Color>getEnum("color"), equalTo(Color.RED));
+		assertTrue(a.getClass("clazz").equals(Integer.class));
 		assertThat(a.getClassArray("classes"), equalTo(new Class[] { Number.class, Short.class, Integer.class }));
-		assertThat(a.getInt("number"), equalTo(42));
-		assertThat(a.getAnnotation("anno").getInt("value"), equalTo(10));
+		assertThat(a.<Integer>getNumber("number"), equalTo(42));
+		assertThat(a.getAnnotation("anno").<Integer>getNumber("value"), equalTo(10));
 		assertThat(a.getAnnotationArray("annoArray")[0].getString("name"), equalTo("algernon"));
 	}
 
@@ -68,13 +68,13 @@ public void getEnum_emptyAttributeName() {
 		AnnotationAttributes a = new AnnotationAttributes();
 		a.put("color", "RED");
 		try {
-			a.getEnum("", Color.class);
+			a.getEnum("");
 			fail();
 		} catch (IllegalArgumentException ex) {
 			assertThat(ex.getMessage(), equalTo("attributeName must not be null or empty"));
 		}
 		try {
-			a.getEnum(null, Color.class);
+			a.getEnum(null);
 			fail();
 		} catch (IllegalArgumentException ex) {
 			assertThat(ex.getMessage(), equalTo("attributeName must not be null or empty"));
@@ -86,7 +86,7 @@ public void getEnum_notFound() {
 		AnnotationAttributes a = new AnnotationAttributes();
 		a.put("color", "RED");
 		try {
-			a.getEnum("colour", Color.class);
+			a.getEnum("colour");
 			fail();
 		} catch (IllegalArgumentException ex) {
 			assertThat(ex.getMessage(), equalTo("Attribute 'colour' not found"));
@@ -98,11 +98,11 @@ public void getEnum_typeMismatch() {
 		AnnotationAttributes a = new AnnotationAttributes();
 		a.put("color", "RED");
 		try {
-			a.getEnum("color", Color.class);
+			a.getEnum("color");
 			fail();
 		} catch (IllegalArgumentException ex) {
 			String expected =
-					"Attribute 'color' is of type [String], but [Color] was expected";
+					"Attribute 'color' is of type [String], but [Enum] was expected";
 			assertThat(ex.getMessage().substring(0, expected.length()), equalTo(expected));
 		}
 	}

org.springframework.core/src/test/java/org/springframework/core/type/AnnotationMetadataTests.java

@@ -109,34 +109,34 @@ private void doTestAnnotationInfo(AnnotationMetadata metadata) {
 		{ // perform tests with classValuesAsString = false (the default)
 			AnnotationAttributes specialAttrs = (AnnotationAttributes) metadata.getAnnotationAttributes(SpecialAttr.class.getName());
 			assertThat(specialAttrs.size(), is(6));
-			assertTrue(String.class.isAssignableFrom(specialAttrs.getClass("clazz", Object.class)));
-			assertThat(specialAttrs.getEnum("state", Thread.State.class), is(Thread.State.NEW));
+			assertTrue(String.class.isAssignableFrom(specialAttrs.getClass("clazz")));
+			assertTrue(specialAttrs.getEnum("state").equals(Thread.State.NEW));
 
 			AnnotationAttributes nestedAnno = specialAttrs.getAnnotation("nestedAnno");
 			assertThat("na", is(nestedAnno.getString("value")));
-			assertThat(nestedAnno.getEnum("anEnum", SomeEnum.class), is(SomeEnum.LABEL1));
+			assertTrue(nestedAnno.getEnum("anEnum").equals(SomeEnum.LABEL1));
 			assertArrayEquals(new Class[]{String.class}, (Class[])nestedAnno.get("classArray"));
 
 			AnnotationAttributes[] nestedAnnoArray = specialAttrs.getAnnotationArray("nestedAnnoArray");
 			assertThat(nestedAnnoArray.length, is(2));
 			assertThat(nestedAnnoArray[0].getString("value"), is("default"));
-			assertThat(nestedAnnoArray[0].getEnum("anEnum", SomeEnum.class), is(SomeEnum.DEFAULT));
+			assertTrue(nestedAnnoArray[0].getEnum("anEnum").equals(SomeEnum.DEFAULT));
 			assertArrayEquals(new Class[]{Void.class}, (Class[])nestedAnnoArray[0].get("classArray"));
 			assertThat(nestedAnnoArray[1].getString("value"), is("na1"));
-			assertThat(nestedAnnoArray[1].getEnum("anEnum", SomeEnum.class), is(SomeEnum.LABEL2));
+			assertTrue(nestedAnnoArray[1].getEnum("anEnum").equals(SomeEnum.LABEL2));
 			assertArrayEquals(new Class[]{Number.class}, (Class[])nestedAnnoArray[1].get("classArray"));
 			assertArrayEquals(new Class[]{Number.class}, nestedAnnoArray[1].getClassArray("classArray"));
 
 			AnnotationAttributes optional = specialAttrs.getAnnotation("optional");
 			assertThat(optional.getString("value"), is("optional"));
-			assertThat(optional.getEnum("anEnum", SomeEnum.class), is(SomeEnum.DEFAULT));
+			assertTrue(optional.getEnum("anEnum").equals(SomeEnum.DEFAULT));
 			assertArrayEquals(new Class[]{Void.class}, (Class[])optional.get("classArray"));
 			assertArrayEquals(new Class[]{Void.class}, optional.getClassArray("classArray"));
 
 			AnnotationAttributes[] optionalArray = specialAttrs.getAnnotationArray("optionalArray");
 			assertThat(optionalArray.length, is(1));
 			assertThat(optionalArray[0].getString("value"), is("optional"));
-			assertThat(optionalArray[0].getEnum("anEnum", SomeEnum.class), is(SomeEnum.DEFAULT));
+			assertTrue(optionalArray[0].getEnum("anEnum").equals(SomeEnum.DEFAULT));
 			assertArrayEquals(new Class[]{Void.class}, (Class[])optionalArray[0].get("classArray"));
 			assertArrayEquals(new Class[]{Void.class}, optionalArray[0].getClassArray("classArray"));
 		}

org.springframework.transaction/src/main/java/org/springframework/transaction/annotation/ProxyTransactionManagementConfiguration.java

@@ -44,7 +44,7 @@ public BeanFactoryTransactionAttributeSourceAdvisor transactionAdvisor() {
 			new BeanFactoryTransactionAttributeSourceAdvisor();
 		advisor.setTransactionAttributeSource(transactionAttributeSource());
 		advisor.setAdvice(transactionInterceptor());
-		advisor.setOrder(this.enableTx.getInt("order"));
+		advisor.setOrder(this.enableTx.<Integer>getNumber("order"));
 		return advisor;
 	}