Add fallbackToSystemLocale configuration key

Allow to configure the `fallbackToSystemLocale` attribute of
`MessageSource` via configuration.

Closes gh-3749

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

@@ -48,6 +48,7 @@ import static org.springframework.util.StringUtils.trimAllWhitespace;
  *
  * @author Dave Syer
  * @author Phillip Webb
+ * @author Eddú Meléndez
  */
 @Configuration
 @ConditionalOnMissingBean(MessageSource.class)
@@ -77,6 +78,11 @@ public class MessageSourceAutoConfiguration {
 	 */
 	private int cacheSeconds = -1;
 
+	/**
+	 * Fall back to the system locale.
+	 */
+	private boolean fallbackToSystemLocale = true;
+
 	@Bean
 	public MessageSource messageSource() {
 		ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
@@ -87,6 +93,7 @@ public class MessageSourceAutoConfiguration {
 		if (this.encoding != null) {
 			messageSource.setDefaultEncoding(this.encoding.name());
 		}
+		messageSource.setFallbackToSystemLocale(this.fallbackToSystemLocale);
 		messageSource.setCacheSeconds(this.cacheSeconds);
 		return messageSource;
 	}
@@ -115,6 +122,14 @@ public class MessageSourceAutoConfiguration {
 		this.cacheSeconds = cacheSeconds;
 	}
 
+	public boolean isFallbackToSystemLocale() {
+		return this.fallbackToSystemLocale;
+	}
+
+	public void setFallbackToSystemLocale(boolean fallbackToSystemLocale) {
+		this.fallbackToSystemLocale = fallbackToSystemLocale;
+	}
+
 	protected static class ResourceBundleCondition extends SpringBootCondition {
 
 		private static ConcurrentReferenceHashMap<String, ConditionOutcome> cache = new ConcurrentReferenceHashMap<String, ConditionOutcome>();

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2014 the original author or authors.
+ * Copyright 2012-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,8 +24,11 @@ import org.springframework.boot.test.EnvironmentTestUtils;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.PropertySource;
+import org.springframework.core.env.Environment;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 
 /**
  * Tests for {@link MessageSourceAutoConfiguration}.
@@ -78,8 +81,7 @@ public class MessageSourceAutoConfigurationTests {
 		this.context.register(MessageSourceAutoConfiguration.class,
 				PropertyPlaceholderAutoConfiguration.class);
 		this.context.refresh();
-		assertEquals("bar",
-				this.context.getMessage("foo", null, "Foo message", Locale.UK));
+		assertEquals("bar", this.context.getMessage("foo", null, "Foo message", Locale.UK));
 		assertEquals("bar-bar",
 				this.context.getMessage("foo-foo", null, "Foo-Foo message", Locale.UK));
 	}
@@ -87,8 +89,7 @@ public class MessageSourceAutoConfigurationTests {
 	@Test
 	public void testBadEncoding() throws Exception {
 		this.context = new AnnotationConfigApplicationContext();
-		EnvironmentTestUtils.addEnvironment(this.context,
-				"spring.messages.encoding:rubbish");
+		EnvironmentTestUtils.addEnvironment(this.context, "spring.messages.encoding:rubbish");
 		this.context.register(MessageSourceAutoConfiguration.class,
 				PropertyPlaceholderAutoConfiguration.class);
 		this.context.refresh();
@@ -107,6 +108,35 @@ public class MessageSourceAutoConfigurationTests {
 				this.context.getMessage("foo", null, "Foo message", Locale.UK));
 	}
 
+	@Test
+	public void testFallbackDefault() throws Exception {
+		this.context = new AnnotationConfigApplicationContext();
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.messages.basename:test/messages");
+		this.context.register(MessageSourceAutoConfiguration.class,
+				PropertyPlaceholderAutoConfiguration.class);
+		this.context.refresh();
+
+		assertTrue(this.context.getBean(MessageSourceAutoConfiguration.class)
+				.isFallbackToSystemLocale());
+		assertEquals("bar", this.context.getMessage("foo", null, "bar", Locale.UK));
+	}
+
+	@Test
+	public void testFallbackTurnOff() throws Exception {
+		this.context = new AnnotationConfigApplicationContext();
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.messages.basename:test/messages",
+				"spring.messages.fallback-to-system-locale:false");
+		this.context.register(MessageSourceAutoConfiguration.class,
+				PropertyPlaceholderAutoConfiguration.class);
+		this.context.refresh();
+
+		assertFalse(this.context.getBean(MessageSourceAutoConfiguration.class)
+				.isFallbackToSystemLocale());
+		assertEquals("bar", this.context.getMessage("foo", null, "bar", Locale.UK));
+	}
+
 	@Configuration
 	@PropertySource("classpath:/switch-messages.properties")
 	protected static class Config {

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

@@ -279,6 +279,7 @@ content into your application; rather pick only the properties that you need.
 	spring.messages.basename=messages
 	spring.messages.cache-seconds=-1
 	spring.messages.encoding=UTF-8
+	spring.messages.fallback-to-system-locale=true
 
 	[[common-application-properties-security]]
 	# SECURITY ({sc-spring-boot-autoconfigure}/security/SecurityProperties.{sc-ext}[SecurityProperties])