Merge pull request #13377 from ruifigueira

* pr/13377:
  Polish "Add ReloadableResourceBundleMessageSource support"
  Add ReloadableResourceBundleMessageSource support

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/context/MessageSourceAutoConfiguration.java

@@ -33,6 +33,8 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.ConditionContext;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.support.AbstractResourceBasedMessageSource;
+import org.springframework.context.support.ReloadableResourceBundleMessageSource;
 import org.springframework.context.support.ResourceBundleMessageSource;
 import org.springframework.core.Ordered;
 import org.springframework.core.io.Resource;
@@ -65,7 +67,9 @@ public class MessageSourceAutoConfiguration {
 
 	@Bean
 	public MessageSource messageSource(MessageSourceProperties properties) {
-		ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
+		AbstractResourceBasedMessageSource messageSource = (properties.isReloadable()
+				? new ReloadableResourceBundleMessageSource()
+				: new ResourceBundleMessageSource());
 		if (StringUtils.hasText(properties.getBasename())) {
 			messageSource.setBasenames(StringUtils.commaDelimitedListToStringArray(
 					StringUtils.trimAllWhitespace(properties.getBasename())));

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/context/MessageSourceProperties.java

@@ -71,6 +71,12 @@ public class MessageSourceProperties {
 	 */
 	private boolean useCodeAsDefaultMessage = false;
 
+	/**
+	 * Whether to use a "ReloadableResourceBundleMessageSource" rather than the default
+	 * "ResourceBundleMessageSource". Recommended during development only.
+	 */
+	private boolean reloadable = false;
+
 	public String getBasename() {
 		return this.basename;
 	}
@@ -119,4 +125,12 @@ public class MessageSourceProperties {
 		this.useCodeAsDefaultMessage = useCodeAsDefaultMessage;
 	}
 
+	public boolean isReloadable() {
+		return this.reloadable;
+	}
+
+	public void setReloadable(boolean reloadable) {
+		this.reloadable = reloadable;
+	}
+
 }

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/context/MessageSourceAutoConfigurationTests.java

@@ -32,6 +32,9 @@ import org.springframework.context.NoSuchMessageException;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.PropertySource;
+import org.springframework.context.support.DelegatingMessageSource;
+import org.springframework.context.support.ReloadableResourceBundleMessageSource;
+import org.springframework.context.support.ResourceBundleMessageSource;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -220,6 +223,38 @@ public class MessageSourceAutoConfigurationTests {
 								.isEqualTo("bar")));
 	}
 
+	@Test
+	public void testDefaultReloadableValueMessageSource() {
+		testReloadableMessageSource(ResourceBundleMessageSource.class,
+				"spring.messages.basename:test/messages");
+	}
+
+	@Test
+	public void testNotReloadableMessageSource() {
+		testReloadableMessageSource(ResourceBundleMessageSource.class,
+				"spring.messages.basename:test/messages",
+				"spring.messages.reloadable:false");
+	}
+
+	@Test
+	public void testReloadableMessageSource() {
+		testReloadableMessageSource(ReloadableResourceBundleMessageSource.class,
+				"spring.messages.basename:test/messages",
+				"spring.messages.reloadable:true");
+	}
+
+	private void testReloadableMessageSource(Class<?> expectedInstance,
+			String... propertyValues) {
+		this.contextRunner.withPropertyValues(propertyValues).run((context) -> {
+			MessageSource messageSource = context.getBean(MessageSource.class);
+			if (messageSource instanceof DelegatingMessageSource) {
+				messageSource = ((DelegatingMessageSource) messageSource)
+						.getParentMessageSource();
+			}
+			assertThat(messageSource).isInstanceOf(expectedInstance);
+		});
+	}
+
 	@Configuration
 	@PropertySource("classpath:/switch-messages.properties")
 	protected static class Config {

spring-boot-project/spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -133,6 +133,7 @@ content into your application. Rather, pick only the properties that you need.
 	spring.messages.cache-duration= # Loaded resource bundle files cache duration. When not set, bundles are cached forever. If a duration suffix is not specified, seconds will be used.
 	spring.messages.encoding=UTF-8 # Message bundles encoding.
 	spring.messages.fallback-to-system-locale=true # Whether to fall back to the system Locale if no files for a specific Locale have been found.
+	spring.messages.reloadable=false # Whether to use a ReloadableResourceBundleMessageSource instead of the default ResourceBundleMessageSource. Recommended during development only.
 	spring.messages.use-code-as-default-message=false # Whether to use the message code as the default message instead of throwing a "NoSuchMessageException". Recommended during development only.
 
 	# OUTPUT