Permit to disable JTA using a single property

Disable JTA auto-configuration altogether with a simple property. This
can be useful if the environment is JTA capable but the application does
not require it.

Fixes gh-1457

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jta/JtaAutoConfiguration.java

@@ -18,6 +18,7 @@ package org.springframework.boot.autoconfigure.jta;
 
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Import;
 
@@ -29,6 +30,7 @@ import org.springframework.context.annotation.Import;
  * @since 1.2.0
  */
 @ConditionalOnClass(javax.transaction.Transaction.class)
+@ConditionalOnProperty(prefix = "spring.jta", value = "enabled", matchIfMissing = true)
 @Import({ JndiJtaConfiguration.class, BitronixJtaConfiguration.class,
 		AtomikosJtaConfiguration.class })
 @EnableConfigurationProperties(JtaProperties.class)

spring-boot-autoconfigure/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -59,6 +59,12 @@
     "description": "Automatically register OpenEntityManagerInViewInterceptor. Binds a JPA EntityManager to the thread for the entire processing of the request.",
     "defaultValue": true
   },
+  {
+    "name": "spring.jta.enabled",
+    "dataType": "java.lang.Boolean",
+    "description": "Enable JTA support.",
+    "defaultValue": true
+  },
   {
     "name": "spring.mobile.devicedelegatingviewresolver.enabled",
     "dataType": "java.lang.Boolean",

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jta/JtaAutoConfigurationTests.java

@@ -49,6 +49,7 @@ import com.atomikos.icatch.jta.UserTransactionManager;
 
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.Mockito.mock;
@@ -87,6 +88,18 @@ public class JtaAutoConfigurationTests {
 		this.context.getBean(JtaTransactionManager.class);
 	}
 
+	@Test
+	public void disableJtaSupport() {
+		this.context = new AnnotationConfigApplicationContext();
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.jta.enabled:false");
+		this.context.register(JtaAutoConfiguration.class);
+		this.context.refresh();
+		assertEquals(0, this.context.getBeansOfType(JtaTransactionManager.class).size());
+		assertEquals(0, this.context.getBeansOfType(XADataSourceWrapper.class).size());
+		assertEquals(0, this.context.getBeansOfType(XAConnectionFactoryWrapper.class).size());
+	}
+
 	@Test
 	public void atomikosSanityCheck() throws Exception {
 		this.context = new AnnotationConfigApplicationContext(JtaProperties.class,

spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -2032,7 +2032,9 @@ transactions are also supported when deploying to a suitable Java EE Application
 When a JTA environment is detected, Spring's `JtaTransactionManager` will be used to manage
 transactions. Auto-configured JMS, DataSource and JPA beans will be upgraded to support
 XA transactions. You can use standard Spring idioms such as `@Transactional` to
-participate in a distributed transaction.
+participate in a distributed transaction. If you are within a JTA environment and still
+want to use local transactions you can set the `spring.jta.enabled` property to `false` to
+disable the JTA auto-configuration.