Consider primary attribute with getBean(Class)

Update DefaultListableBeanFactory.getBean(Class<?> beanClass) to
consider the 'primary' attribute of bean definitions. This makes
getBean() behave in the same way as autowiring.

Issue: SPR-7854

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

@@ -90,6 +90,7 @@ import org.springframework.util.StringUtils;
  * @author Sam Brannen
  * @author Costin Leau
  * @author Chris Beams
+ * @author Phillip Webb
  * @since 16 April 2001
  * @see StaticListableBeanFactory
  * @see PropertiesBeanDefinitionReader
@@ -272,6 +273,20 @@ public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFacto
 			return getBean(beanNames[0], requiredType);
 		}
 		else if (beanNames.length > 1) {
+			T primaryBean = null;
+			for (String beanName : beanNames) {
+				T beanInstance = getBean(beanName, requiredType);
+				if (isPrimary(beanName, beanInstance)) {
+					if(primaryBean != null) {
+						throw new NoUniqueBeanDefinitionException(requiredType, beanNames.length,
+								"more than one 'primary' bean found of required type: " + Arrays.asList(beanNames));
+					}
+					primaryBean = beanInstance;
+				}
+			}
+			if(primaryBean != null) {
+				return primaryBean;
+			}
 			throw new NoUniqueBeanDefinitionException(requiredType, beanNames);
 		}
 		else if (getParentBeanFactory() != null) {

spring-beans/src/test/java/org/springframework/beans/factory/DefaultListableBeanFactoryTests.java

@@ -17,6 +17,8 @@
 package org.springframework.beans.factory;
 
 import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.equalTo;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
@@ -49,7 +51,9 @@ import javax.security.auth.Subject;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.junit.Ignore;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 import org.springframework.beans.BeansException;
 import org.springframework.beans.MutablePropertyValues;
 import org.springframework.beans.NotWritablePropertyException;
@@ -102,11 +106,14 @@ import org.springframework.util.StopWatch;
  * @author Rick Evans
  * @author Sam Brannen
  * @author Chris Beams
+ * @author Phillip Webb
  */
 public class DefaultListableBeanFactoryTests {
 
 	private static final Log factoryLog = LogFactory.getLog(DefaultListableBeanFactory.class);
 
+	@Rule
+	public ExpectedException thrown = ExpectedException.none();
 
 	@Test
 	public void testUnreferencedSingletonWasInstantiated() {
@@ -1285,6 +1292,32 @@ public class DefaultListableBeanFactoryTests {
 		lbf.getBean(TestBean.class);
 	}
 
+	@Test
+	public void testGetBeanByTypeWithPrimary() throws Exception {
+		DefaultListableBeanFactory lbf = new DefaultListableBeanFactory();
+		RootBeanDefinition bd1 = new RootBeanDefinition(TestBean.class);
+		RootBeanDefinition bd2 = new RootBeanDefinition(TestBean.class);
+		bd2.setPrimary(true);
+		lbf.registerBeanDefinition("bd1", bd1);
+		lbf.registerBeanDefinition("bd2", bd2);
+		TestBean bean = lbf.getBean(TestBean.class);
+		assertThat(bean.getBeanName(), equalTo("bd2"));
+	}
+
+	@Test
+	public void testGetBeanByTypeWithMultiplePrimary() throws Exception {
+		DefaultListableBeanFactory lbf = new DefaultListableBeanFactory();
+		RootBeanDefinition bd1 = new RootBeanDefinition(TestBean.class);
+		bd1.setPrimary(true);
+		RootBeanDefinition bd2 = new RootBeanDefinition(TestBean.class);
+		bd2.setPrimary(true);
+		lbf.registerBeanDefinition("bd1", bd1);
+		lbf.registerBeanDefinition("bd2", bd2);
+		thrown.expect(NoUniqueBeanDefinitionException.class);
+		thrown.expectMessage(containsString("more than one 'primary'"));
+		lbf.getBean(TestBean.class);
+	}
+
 	@Test
 	public void testGetBeanByTypeFiltersOutNonAutowireCandidates() {
 		DefaultListableBeanFactory lbf = new DefaultListableBeanFactory();