Reuse JdbcTemplate in NamedParameterJdbcTemplate

This commit makes sure to reuse an existing or auto-configured
`JdbcTemplate` when auto-configuring a `NamedParameterJdbcTemplate`.

This ensures that whatever customizations have been applied on the
`JdbcTemplate` are properly shared.

Closes gh-4945

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jdbc/JdbcTemplateAutoConfiguration.java

@@ -25,6 +25,7 @@ import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean
 import org.springframework.boot.autoconfigure.condition.ConditionalOnSingleCandidate;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
 import org.springframework.context.annotation.Primary;
 import org.springframework.jdbc.core.JdbcOperations;
 import org.springframework.jdbc.core.JdbcTemplate;
@@ -47,24 +48,36 @@ import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;
 @AutoConfigureAfter(DataSourceAutoConfiguration.class)
 public class JdbcTemplateAutoConfiguration {
 
-	private final DataSource dataSource;
+	@Configuration
+	static class JdbcTemplateConfiguration {
+
+		private final DataSource dataSource;
+
+		JdbcTemplateConfiguration(DataSource dataSource) {
+			this.dataSource = dataSource;
+		}
+
+		@Bean
+		@Primary
+		@ConditionalOnMissingBean(JdbcOperations.class)
+		public JdbcTemplate jdbcTemplate() {
+			return new JdbcTemplate(this.dataSource);
+		}
 
-	public JdbcTemplateAutoConfiguration(DataSource dataSource) {
-		this.dataSource = dataSource;
 	}
 
-	@Bean
-	@Primary
-	@ConditionalOnMissingBean(JdbcOperations.class)
-	public JdbcTemplate jdbcTemplate() {
-		return new JdbcTemplate(this.dataSource);
-	}
+	@Configuration
+	@Import(JdbcTemplateConfiguration.class)
+	static class NamedParameterJdbcTemplateConfiguration {
+
+		@Bean
+		@Primary
+		@ConditionalOnSingleCandidate(JdbcTemplate.class)
+		@ConditionalOnMissingBean(NamedParameterJdbcOperations.class)
+		public NamedParameterJdbcTemplate namedParameterJdbcTemplate(JdbcTemplate jdbcTemplate) {
+			return new NamedParameterJdbcTemplate(jdbcTemplate);
+		}
 
-	@Bean
-	@Primary
-	@ConditionalOnMissingBean(NamedParameterJdbcOperations.class)
-	public NamedParameterJdbcTemplate namedParameterJdbcTemplate() {
-		return new NamedParameterJdbcTemplate(this.dataSource);
 	}
 
 }

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jdbc/JdbcTemplateAutoConfigurationTests.java

@@ -28,12 +28,14 @@ import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Primary;
 import org.springframework.jdbc.core.JdbcOperations;
 import org.springframework.jdbc.core.JdbcTemplate;
 import org.springframework.jdbc.core.namedparam.NamedParameterJdbcOperations;
 import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
 
 /**
  * Tests for {@link JdbcTemplateAutoConfiguration}.
@@ -56,7 +58,7 @@ public class JdbcTemplateAutoConfigurationTests {
 	@Test
 	public void testJdbcTemplateExists() {
 		load();
-		assertThat(this.context.getBeansOfType(JdbcTemplate.class)).hasSize(1);
+		assertThat(this.context.getBeansOfType(JdbcOperations.class)).hasSize(1);
 		JdbcTemplate jdbcTemplate = this.context.getBean(JdbcTemplate.class);
 		assertThat(jdbcTemplate.getDataSource()).isEqualTo(
 				this.context.getBean(DataSource.class));
@@ -65,7 +67,7 @@ public class JdbcTemplateAutoConfigurationTests {
 	@Test
 	public void testJdbcTemplateExistsWithCustomDataSource() {
 		load(TestDataSourceConfiguration.class);
-		assertThat(this.context.getBeansOfType(JdbcTemplate.class)).hasSize(1);
+		assertThat(this.context.getBeansOfType(JdbcOperations.class)).hasSize(1);
 		JdbcTemplate jdbcTemplate = this.context.getBean(JdbcTemplate.class);
 		assertThat(jdbcTemplate).isNotNull();
 		assertThat(jdbcTemplate.getDataSource()).isEqualTo(
@@ -77,6 +79,10 @@ public class JdbcTemplateAutoConfigurationTests {
 		load();
 		assertThat(this.context.getBeansOfType(NamedParameterJdbcOperations.class))
 				.hasSize(1);
+		NamedParameterJdbcTemplate namedParameterJdbcTemplate = this.context.getBean(
+				NamedParameterJdbcTemplate.class);
+		assertThat(namedParameterJdbcTemplate.getJdbcOperations()).isEqualTo(
+				this.context.getBean(JdbcOperations.class));
 	}
 
 	@Test
@@ -87,6 +93,13 @@ public class JdbcTemplateAutoConfigurationTests {
 				.isEmpty();
 	}
 
+	@Test
+	public void testMultiJdbcTemplate() {
+		load(MultiJdbcTemplateConfiguration.class);
+		assertThat(this.context.getBeansOfType(NamedParameterJdbcOperations.class))
+				.isEmpty();
+	}
+
 	@Test
 	public void testMultiDataSourceUsingPrimary() {
 		load(MultiDataSourceUsingPrimaryConfiguration.class);
@@ -97,6 +110,15 @@ public class JdbcTemplateAutoConfigurationTests {
 				.isEqualTo(this.context.getBean("test1DataSource"));
 	}
 
+	@Test
+	public void testMultiJdbcTemplateUsingPrimary() {
+		load(MultiJdbcTemplateUsingPrimaryConfiguration.class);
+		assertThat(this.context.getBeansOfType(NamedParameterJdbcOperations.class))
+				.hasSize(1);
+		assertThat(this.context.getBean(NamedParameterJdbcTemplate.class)
+				.getJdbcOperations()).isEqualTo(this.context.getBean("test1Template"));
+	}
+
 	@Test
 	public void testExistingCustomJdbcTemplate() {
 		load(CustomConfiguration.class);
@@ -159,4 +181,35 @@ public class JdbcTemplateAutoConfigurationTests {
 
 	}
 
+	@Configuration
+	static class MultiJdbcTemplateConfiguration {
+
+		@Bean
+		public JdbcTemplate test1Template() {
+			return mock(JdbcTemplate.class);
+		}
+
+		@Bean
+		public JdbcTemplate test2Template() {
+			return mock(JdbcTemplate.class);
+		}
+
+	}
+
+	@Configuration
+	static class MultiJdbcTemplateUsingPrimaryConfiguration {
+
+		@Bean
+		@Primary
+		public JdbcTemplate test1Template() {
+			return mock(JdbcTemplate.class);
+		}
+
+		@Bean
+		public JdbcTemplate test2Template() {
+			return mock(JdbcTemplate.class);
+		}
+
+	}
+
 }

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

@@ -2932,6 +2932,9 @@ you can `@Autowire` them directly into your own beans:
 	}
 ----
 
+TIP: The `NamedParameterJdbcTemplate` reuses the same `JdbcTemplate` instance behind the
+scene. If more than one `JdbcTemplate` is defined and no primary candidate exists, the
+`NamedParameterJdbcTemplate` is not auto-configured.
 
 
 [[boot-features-jpa-and-spring-data]]