Introduce 'value' alias for @bean's 'name' attribute

In order to simplify configuration for use cases involving @bean where
only a bean name or aliases are supplied as an attribute, this commit
introduces a new 'value' attribute that is an @AliasFor 'name' in @bean.

Issue: SPR-14728
(cherry picked from commit 8f62b63)

Author: sbrannen

spring-context/src/main/java/org/springframework/context/annotation/Bean.java

@@ -24,6 +24,7 @@
 
 import org.springframework.beans.factory.annotation.Autowire;
 import org.springframework.beans.factory.support.AbstractBeanDefinition;
+import org.springframework.core.annotation.AliasFor;
 
 /**
  * Indicates that a method produces a bean to be managed by the Spring container.
@@ -44,15 +45,15 @@
  *
  * <h3>Bean Names</h3>
  *
- * <p>While a {@link #name() name} attribute is available, the default strategy for
+ * <p>While a {@link #name} attribute is available, the default strategy for
  * determining the name of a bean is to use the name of the {@code @Bean} method.
  * This is convenient and intuitive, but if explicit naming is desired, the
- * {@code name} attribute may be used. Also note that {@code name} accepts an array
- * of Strings. This is in order to allow for specifying multiple names (i.e., aliases)
- * for a single bean.
+ * {@code name} attribute (or its alias {@code value}) may be used. Also note
+ * that {@code name} accepts an array of Strings, allowing for multiple names
+ * (i.e. a primary bean name plus one or more aliases) for a single bean.
  *
  * <pre class="code">
- *     &#064;Bean(name={"b1","b2"}) // bean available as 'b1' and 'b2', but not 'myBean'
+ *     &#064;Bean({"b1", "b2"}) // bean available as 'b1' and 'b2', but not 'myBean'
  *     public MyBean myBean() {
  *         // instantiate and configure MyBean obj
  *         return obj;
@@ -78,9 +79,9 @@
  * <h3>{@code @Bean} Methods in {@code @Configuration} Classes</h3>
  *
  * <p>Typically, {@code @Bean} methods are declared within {@code @Configuration}
- * classes. In this case, bean methods may reference other {@code @Bean} methods
- * in the same class by calling them <i>directly</i>. This ensures that references between
- * beans are strongly typed and navigable. Such so-called <em>'inter-bean references'</em> are
+ * classes. In this case, bean methods may reference other {@code @Bean} methods in the
+ * same class by calling them <i>directly</i>. This ensures that references between beans
+ * are strongly typed and navigable. Such so-called <em>'inter-bean references'</em> are
  * guaranteed to respect scoping and AOP semantics, just like {@code getBean()} lookups
  * would. These are the semantics known from the original 'Spring JavaConfig' project
  * which require CGLIB subclassing of each such configuration class at runtime. As a
@@ -190,10 +191,24 @@
 public @interface Bean {
 
 	/**
-	 * The name of this bean, or if plural, aliases for this bean. If left unspecified
-	 * the name of the bean is the name of the annotated method. If specified, the method
-	 * name is ignored.
+	 * Alias for {@link #name}.
+	 * <p>Intended to be used when no other attributes are needed, for example:
+	 * {@code @Bean("customBeanName")}.
+	 * @since 4.3.3
+	 * @see #name
 	 */
+	@AliasFor("name")
+	String[] value() default {};
+
+	/**
+	 * The name of this bean, or if several names, a primary bean name plus aliases.
+	 * <p>If left unspecified, the name of the bean is the name of the annotated method.
+	 * If specified, the method name is ignored.
+	 * <p>The bean name and aliases may also be configured via the {@link #value}
+	 * attribute if no other attributes are declared.
+	 * @see #value
+	 */
+	@AliasFor("value")
 	String[] name() default {};
 
 	/**

spring-context/src/test/java/org/springframework/context/annotation/configuration/ConfigurationClassProcessingTests.java

@@ -20,9 +20,12 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Set;
+import java.util.function.Supplier;
 import javax.inject.Provider;
 
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 
 import org.springframework.beans.factory.BeanClassLoaderAware;
 import org.springframework.beans.factory.BeanFactory;
@@ -65,6 +68,7 @@
  *
  * @author Chris Beams
  * @author Juergen Hoeller
+ * @author Sam Brannen
  */
 public class ConfigurationClassProcessingTests {
 
@@ -92,40 +96,57 @@ private DefaultListableBeanFactory initBeanFactory(Class<?>... configClasses) {
 	}
 
 
+	@Rule
+	public final ExpectedException exception = ExpectedException.none();
+
+
+	@Test
+	public void customBeanNameIsRespectedWhenConfiguredViaNameAttribute() {
+		customBeanNameIsRespected(ConfigWithBeanWithCustomName.class,
+				() -> ConfigWithBeanWithCustomName.testBean, "customName");
+	}
+
 	@Test
-	public void customBeanNameIsRespected() {
+	public void customBeanNameIsRespectedWhenConfiguredViaValueAttribute() {
+		customBeanNameIsRespected(ConfigWithBeanWithCustomNameConfiguredViaValueAttribute.class,
+				() -> ConfigWithBeanWithCustomNameConfiguredViaValueAttribute.testBean, "enigma");
+	}
+
+	private void customBeanNameIsRespected(Class<?> testClass, Supplier<TestBean> testBeanSupplier, String beanName) {
 		GenericApplicationContext ac = new GenericApplicationContext();
 		AnnotationConfigUtils.registerAnnotationConfigProcessors(ac);
-		ac.registerBeanDefinition("config", new RootBeanDefinition(ConfigWithBeanWithCustomName.class));
+		ac.registerBeanDefinition("config", new RootBeanDefinition(testClass));
 		ac.refresh();
-		assertSame(ac.getBean("customName"), ConfigWithBeanWithCustomName.testBean);
+
+		assertSame(testBeanSupplier.get(), ac.getBean(beanName));
 
 		// method name should not be registered
-		try {
-			ac.getBean("methodName");
-			fail("bean should not have been registered with 'methodName'");
-		}
-		catch (NoSuchBeanDefinitionException ex) {
-			// expected
-		}
+		exception.expect(NoSuchBeanDefinitionException.class);
+		ac.getBean("methodName");
 	}
 
 	@Test
-	public void aliasesAreRespected() {
-		BeanFactory factory = initBeanFactory(ConfigWithBeanWithAliases.class);
-		assertSame(factory.getBean("name1"), ConfigWithBeanWithAliases.testBean);
-		String[] aliases = factory.getAliases("name1");
-		for (String alias : aliases)
-			assertSame(factory.getBean(alias), ConfigWithBeanWithAliases.testBean);
+	public void aliasesAreRespectedWhenConfiguredViaNameAttribute() {
+		aliasesAreRespected(ConfigWithBeanWithAliases.class,
+				() -> ConfigWithBeanWithAliases.testBean, "name1");
+	}
+
+	@Test
+	public void aliasesAreRespectedWhenConfiguredViaValueAttribute() {
+		aliasesAreRespected(ConfigWithBeanWithAliasesConfiguredViaValueAttribute.class,
+				() -> ConfigWithBeanWithAliasesConfiguredViaValueAttribute.testBean, "enigma");
+	}
+
+	private void aliasesAreRespected(Class<?> testClass, Supplier<TestBean> testBeanSupplier, String beanName) {
+		TestBean testBean = testBeanSupplier.get();
+		BeanFactory factory = initBeanFactory(testClass);
+
+		assertSame(testBean, factory.getBean(beanName));
+		Arrays.stream(factory.getAliases(beanName)).map(factory::getBean).forEach(alias -> assertSame(testBean, alias));
 
 		// method name should not be registered
-		try {
-			factory.getBean("methodName");
-			fail("bean should not have been registered with 'methodName'");
-		}
-		catch (NoSuchBeanDefinitionException ex) {
-			// expected
-		}
+		exception.expect(NoSuchBeanDefinitionException.class);
+		factory.getBean("methodName");
 	}
 
 	@Test  // SPR-11830
@@ -146,8 +167,9 @@ public void configWithSetWithProviderImplementation() {
 		assertSame(ac.getBean("customName"), ConfigWithSetWithProviderImplementation.set);
 	}
 
-	@Test(expected=BeanDefinitionParsingException.class)
+	@Test
 	public void testFinalBeanMethod() {
+		exception.expect(BeanDefinitionParsingException.class);
 		initBeanFactory(ConfigWithFinalBean.class);
 	}
 
@@ -219,6 +241,7 @@ public void configurationWithAdaptivePrototypes() {
 		adaptive = factory.getBean(AdaptiveInjectionPoints.class);
 		assertEquals("adaptiveInjectionPoint1", adaptive.adaptiveInjectionPoint1.getName());
 		assertEquals("setAdaptiveInjectionPoint2", adaptive.adaptiveInjectionPoint2.getName());
+		factory.close();
 	}
 
 	@Test
@@ -240,15 +263,28 @@ public void configurationWithPostProcessor() {
 
 		SpousyTestBean listener = factory.getBean("listenerTestBean", SpousyTestBean.class);
 		assertTrue(listener.refreshed);
+		factory.close();
 	}
 
 
 	@Configuration
 	static class ConfigWithBeanWithCustomName {
 
-		static TestBean testBean = new TestBean();
+		static TestBean testBean = new TestBean(ConfigWithBeanWithCustomName.class.getSimpleName());
 
-		@Bean(name="customName")
+		@Bean(name = "customName")
+		public TestBean methodName() {
+			return testBean;
+		}
+	}
+
+
+	@Configuration
+	static class ConfigWithBeanWithCustomNameConfiguredViaValueAttribute {
+
+		static TestBean testBean = new TestBean(ConfigWithBeanWithCustomNameConfiguredViaValueAttribute.class.getSimpleName());
+
+		@Bean("enigma")
 		public TestBean methodName() {
 			return testBean;
 		}
@@ -258,9 +294,21 @@ public TestBean methodName() {
 	@Configuration
 	static class ConfigWithBeanWithAliases {
 
-		static TestBean testBean = new TestBean();
+		static TestBean testBean = new TestBean(ConfigWithBeanWithAliases.class.getSimpleName());
+
+		@Bean(name = { "name1", "alias1", "alias2", "alias3" })
+		public TestBean methodName() {
+			return testBean;
+		}
+	}
+
+
+	@Configuration
+	static class ConfigWithBeanWithAliasesConfiguredViaValueAttribute {
+
+		static TestBean testBean = new TestBean(ConfigWithBeanWithAliasesConfiguredViaValueAttribute.class.getSimpleName());
 
-		@Bean(name={"name1", "alias1", "alias2", "alias3"})
+		@Bean({ "enigma", "alias1", "alias2", "alias3" })
 		public TestBean methodName() {
 			return testBean;
 		}
@@ -270,9 +318,9 @@ public TestBean methodName() {
 	@Configuration
 	static class ConfigWithBeanWithProviderImplementation implements Provider<TestBean> {
 
-		static TestBean testBean = new TestBean();
+		static TestBean testBean = new TestBean(ConfigWithBeanWithProviderImplementation.class.getSimpleName());
 
-		@Bean(name="customName")
+		@Bean(name = "customName")
 		public TestBean get() {
 			return testBean;
 		}
@@ -284,7 +332,7 @@ static class ConfigWithSetWithProviderImplementation implements Provider<Set<Str
 
 		static Set<String> set = Collections.singleton("value");
 
-		@Bean(name="customName")
+		@Bean(name = "customName")
 		public Set<String> get() {
 			return set;
 		}
@@ -406,7 +454,7 @@ public int getOrder() {
 			};
 		}
 
-		//@Bean
+		// @Bean
 		public BeanFactoryPostProcessor beanFactoryPostProcessor() {
 			return new BeanFactoryPostProcessor() {
 				@Override

spring-context/src/test/java/org/springframework/jmx/export/annotation/EnableMBeanExportConfigurationTests.java

@@ -228,7 +228,7 @@ public MBeanServerFactoryBean server() throws Exception {
 			return new MBeanServerFactoryBean();
 		}
 
-		@Bean(name="bean:name=testBean4")
+		@Bean("bean:name=testBean4")
 		@Lazy
 		public AnnotationTestBean testBean4() {
 			AnnotationTestBean bean = new AnnotationTestBean();
@@ -237,7 +237,7 @@ public AnnotationTestBean testBean4() {
 			return bean;
 		}
 
-		@Bean(name="bean:name=testBean5")
+		@Bean("bean:name=testBean5")
 		public AnnotationTestBeanFactory testBean5() throws Exception {
 			return new AnnotationTestBeanFactory();
 		}

spring-webmvc/src/test/java/org/springframework/web/servlet/config/annotation/WebMvcConfigurationSupportTests.java

@@ -333,10 +333,10 @@ private ApplicationContext initContext(Class<?>... configClasses) {
 
 
 	@EnableWebMvc
-	@Configuration @SuppressWarnings("unused")
+	@Configuration
 	static class WebConfig {
 
-		@Bean(name="/testController")
+		@Bean("/testController")
 		public TestController testController() {
 			return new TestController();
 		}
@@ -350,7 +350,7 @@ public MessageSource messageSource() {
 	}
 
 
-	@Configuration @SuppressWarnings("unused")
+	@Configuration
 	static class ViewResolverConfig {
 
 		@Bean
@@ -387,7 +387,7 @@ public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> handler
 	}
 
 
-	@Controller @SuppressWarnings("unused")
+	@Controller
 	private static class TestController {
 
 		@RequestMapping("/")
@@ -413,7 +413,7 @@ public void handle() {
 
 
 	@Controller
-	@Scope(value="prototype", proxyMode=ScopedProxyMode.TARGET_CLASS)
+	@Scope(scopeName = "prototype", proxyMode = ScopedProxyMode.TARGET_CLASS)
 	static class ScopedProxyController {
 
 		@RequestMapping("/scopedProxy")