Check for existence of ResourceBundle before creating MessageSource

Irritatingly a ResourceBundleMessageSource never gives up trying to
create a resource bundle for every message resolution, so to stop
it logging all those warnings (and probably sucking performance-wise)
we need to disable the MessageSource if a bundle is not provided.

Fixes gh-1019

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

@@ -16,16 +16,25 @@
 
 package org.springframework.boot.autoconfigure;
 
+import java.util.Locale;
+import java.util.MissingResourceException;
+import java.util.ResourceBundle;
+
+import org.springframework.boot.autoconfigure.MessageSourceAutoConfiguration.ResourceBundleCondition;
+import org.springframework.boot.autoconfigure.condition.ConditionOutcome;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
-import org.springframework.boot.bind.RelaxedPropertyResolver;
-import org.springframework.context.EnvironmentAware;
+import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.MessageSource;
 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.ResourceBundleMessageSource;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
-import org.springframework.core.env.Environment;
+import org.springframework.core.type.AnnotatedTypeMetadata;
 import org.springframework.util.StringUtils;
 
 import static org.springframework.util.StringUtils.commaDelimitedListToStringArray;
@@ -39,28 +48,77 @@ import static org.springframework.util.StringUtils.trimAllWhitespace;
 @Configuration
 @ConditionalOnMissingBean(MessageSource.class)
 @Order(Ordered.HIGHEST_PRECEDENCE)
-public class MessageSourceAutoConfiguration implements EnvironmentAware {
+@Conditional(ResourceBundleCondition.class)
+@EnableConfigurationProperties
+@ConfigurationProperties(prefix = "spring.messages")
+public class MessageSourceAutoConfiguration {
 
-	private RelaxedPropertyResolver environment;
+	private String basename = "messages";
 
-	@Override
-	public void setEnvironment(Environment environment) {
-		this.environment = new RelaxedPropertyResolver(environment, "spring.messages.");
-	}
+	private String encoding = "utf-8";
+
+	private int cacheSeconds = -1;
 
 	@Bean
 	public MessageSource messageSource() {
 		ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
-		String basename = this.environment.getProperty("basename", "messages");
-		if (StringUtils.hasText(basename)) {
+		if (StringUtils.hasText(this.basename)) {
 			messageSource
-					.setBasenames(commaDelimitedListToStringArray(trimAllWhitespace(basename)));
+					.setBasenames(commaDelimitedListToStringArray(trimAllWhitespace(this.basename)));
 		}
-		String encoding = this.environment.getProperty("encoding", "utf-8");
-		messageSource.setDefaultEncoding(encoding);
-		messageSource.setCacheSeconds(this.environment.getProperty("cacheSeconds",
-				Integer.class, -1));
+		messageSource.setDefaultEncoding(this.encoding);
+		messageSource.setCacheSeconds(this.cacheSeconds);
 		return messageSource;
 	}
 
+	public String getBasename() {
+		return this.basename;
+	}
+
+	public void setBasename(String basename) {
+		this.basename = basename;
+	}
+
+	public String getEncoding() {
+		return this.encoding;
+	}
+
+	public void setEncoding(String encoding) {
+		this.encoding = encoding;
+	}
+
+	public int getCacheSeconds() {
+		return this.cacheSeconds;
+	}
+
+	public void setCacheSeconds(int cacheSeconds) {
+		this.cacheSeconds = cacheSeconds;
+	}
+
+	protected static class ResourceBundleCondition extends SpringBootCondition {
+
+		@Override
+		public ConditionOutcome getMatchOutcome(ConditionContext context,
+				AnnotatedTypeMetadata metadata) {
+			String basename = context.getEnvironment().getProperty(
+					"spring.messages.basename", "messages");
+			if (!StringUtils.hasText(basename)) {
+				return ConditionOutcome.noMatch("Empty spring.messages.basename");
+			}
+			for (String name : commaDelimitedListToStringArray(trimAllWhitespace(basename))) {
+				try {
+					ResourceBundle.getBundle(name, Locale.getDefault(),
+							context.getClassLoader());
+				}
+				catch (MissingResourceException e) {
+					return ConditionOutcome
+							.noMatch("Bundle found for spring.messages.basename: " + name);
+				}
+			}
+			return ConditionOutcome.match("Bundle found for spring.messages.basename: "
+					+ basename);
+		}
+
+	}
+
 }

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

@@ -46,10 +46,10 @@ public class MessageSourceAutoConfigurationTests {
 	@Test
 	public void testMessageSourceCreated() throws Exception {
 		this.context = new AnnotationConfigApplicationContext();
-		this.context.register(MessageSourceAutoConfiguration.class,
-				PropertyPlaceholderAutoConfiguration.class);
 		EnvironmentTestUtils.addEnvironment(this.context,
 				"spring.messages.basename:test/messages");
+		this.context.register(MessageSourceAutoConfiguration.class,
+				PropertyPlaceholderAutoConfiguration.class);
 		this.context.refresh();
 		assertEquals("bar",
 				this.context.getMessage("foo", null, "Foo message", Locale.UK));
@@ -58,10 +58,10 @@ public class MessageSourceAutoConfigurationTests {
 	@Test
 	public void testMultipleMessageSourceCreated() throws Exception {
 		this.context = new AnnotationConfigApplicationContext();
-		this.context.register(MessageSourceAutoConfiguration.class,
-				PropertyPlaceholderAutoConfiguration.class);
 		EnvironmentTestUtils.addEnvironment(this.context,
 				"spring.messages.basename:test/messages,test/messages2");
+		this.context.register(MessageSourceAutoConfiguration.class,
+				PropertyPlaceholderAutoConfiguration.class);
 		this.context.refresh();
 		assertEquals("bar",
 				this.context.getMessage("foo", null, "Foo message", Locale.UK));
@@ -72,10 +72,10 @@ public class MessageSourceAutoConfigurationTests {
 	@Test
 	public void testBadEncoding() throws Exception {
 		this.context = new AnnotationConfigApplicationContext();
-		this.context.register(MessageSourceAutoConfiguration.class,
-				PropertyPlaceholderAutoConfiguration.class);
 		EnvironmentTestUtils.addEnvironment(this.context,
 				"spring.messages.encoding:rubbish");
+		this.context.register(MessageSourceAutoConfiguration.class,
+				PropertyPlaceholderAutoConfiguration.class);
 		this.context.refresh();
 		// Bad encoding just means the messages are ignored
 		assertEquals("blah", this.context.getMessage("foo", null, "blah", Locale.UK));