Allow data source class name to be specified when using Hikari

Closes gh-44938

Author: wilkinsona

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -33,6 +33,7 @@
 import org.springframework.boot.jdbc.DatabaseDriver;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.core.env.Environment;
 import org.springframework.util.StringUtils;
 
 /**
@@ -50,10 +51,17 @@ abstract class DataSourceConfiguration {
 	@SuppressWarnings("unchecked")
 	private static <T> T createDataSource(JdbcConnectionDetails connectionDetails, Class<? extends DataSource> type,
 			ClassLoader classLoader) {
-		return (T) DataSourceBuilder.create(classLoader)
-			.type(type)
-			.driverClassName(connectionDetails.getDriverClassName())
-			.url(connectionDetails.getJdbcUrl())
+		return createDataSource(connectionDetails, type, classLoader, true);
+	}
+
+	@SuppressWarnings("unchecked")
+	private static <T> T createDataSource(JdbcConnectionDetails connectionDetails, Class<? extends DataSource> type,
+			ClassLoader classLoader, boolean applyDriverClassName) {
+		DataSourceBuilder<? extends DataSource> builder = DataSourceBuilder.create(classLoader).type(type);
+		if (applyDriverClassName) {
+			builder.driverClassName(connectionDetails.getDriverClassName());
+		}
+		return (T) builder.url(connectionDetails.getJdbcUrl())
 			.username(connectionDetails.getUsername())
 			.password(connectionDetails.getPassword())
 			.build();
@@ -113,9 +121,11 @@ static HikariJdbcConnectionDetailsBeanPostProcessor jdbcConnectionDetailsHikariB
 
 		@Bean
 		@ConfigurationProperties(prefix = "spring.datasource.hikari")
-		HikariDataSource dataSource(DataSourceProperties properties, JdbcConnectionDetails connectionDetails) {
+		HikariDataSource dataSource(DataSourceProperties properties, JdbcConnectionDetails connectionDetails,
+				Environment environment) {
+			String dataSourceClassName = environment.getProperty("spring.datasource.hikari.data-source-class-name");
 			HikariDataSource dataSource = createDataSource(connectionDetails, HikariDataSource.class,
-					properties.getClassLoader());
+					properties.getClassLoader(), dataSourceClassName == null);
 			if (StringUtils.hasText(properties.getName())) {
 				dataSource.setPoolName(properties.getName());
 			}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -171,6 +171,15 @@ public void setDriverClassName(String driverClassName) {
 	 * @since 1.4.0
 	 */
 	public String determineDriverClassName() {
+		String driverClassName = findDriverClassName();
+		if (!StringUtils.hasText(driverClassName)) {
+			throw new DataSourceBeanCreationException("Failed to determine a suitable driver class", this,
+					this.embeddedDatabaseConnection);
+		}
+		return driverClassName;
+	}
+
+	String findDriverClassName() {
 		if (StringUtils.hasText(this.driverClassName)) {
 			Assert.state(driverClassIsLoadable(), () -> "Cannot load driver class: " + this.driverClassName);
 			return this.driverClassName;
@@ -182,10 +191,6 @@ public String determineDriverClassName() {
 		if (!StringUtils.hasText(driverClassName)) {
 			driverClassName = this.embeddedDatabaseConnection.getDriverClassName();
 		}
-		if (!StringUtils.hasText(driverClassName)) {
-			throw new DataSourceBeanCreationException("Failed to determine a suitable driver class", this,
-					this.embeddedDatabaseConnection);
-		}
 		return driverClassName;
 	}
 
@@ -277,7 +282,7 @@ public String determineUsername() {
 		if (StringUtils.hasText(this.username)) {
 			return this.username;
 		}
-		if (EmbeddedDatabaseConnection.isEmbedded(determineDriverClassName(), determineUrl())) {
+		if (EmbeddedDatabaseConnection.isEmbedded(findDriverClassName(), determineUrl())) {
 			return "sa";
 		}
 		return null;
@@ -305,7 +310,7 @@ public String determinePassword() {
 		if (StringUtils.hasText(this.password)) {
 			return this.password;
 		}
-		if (EmbeddedDatabaseConnection.isEmbedded(determineDriverClassName(), determineUrl())) {
+		if (EmbeddedDatabaseConnection.isEmbedded(findDriverClassName(), determineUrl())) {
 			return "";
 		}
 		return null;

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

@@ -41,7 +41,7 @@ protected Object processDataSource(HikariDataSource dataSource, JdbcConnectionDe
 		dataSource.setPassword(connectionDetails.getPassword());
 		String driverClassName = connectionDetails.getDriverClassName();
 		if (driverClassName != null) {
-			dataSource.setDriverClassName(connectionDetails.getDriverClassName());
+			dataSource.setDriverClassName(driverClassName);
 		}
 		return dataSource;
 	}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2025 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.

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -16,6 +16,12 @@
 
 package org.springframework.boot.autoconfigure.jdbc;
 
+import java.io.PrintWriter;
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.sql.SQLFeatureNotSupportedException;
+import java.util.logging.Logger;
+
 import javax.sql.DataSource;
 
 import com.zaxxer.hikari.HikariDataSource;
@@ -28,12 +34,15 @@
 import org.springframework.boot.jdbc.DataSourceBuilder;
 import org.springframework.boot.jdbc.HikariCheckpointRestoreLifecycle;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.boot.testsupport.classpath.ClassPathExclusions;
 import org.springframework.boot.testsupport.classpath.ClassPathOverrides;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.jdbc.datasource.DelegatingDataSource;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatNoException;
+import static org.mockito.Mockito.mock;
 
 /**
  * Tests for {@link DataSourceAutoConfiguration} with Hikari.
@@ -80,7 +89,33 @@ void testDataSourceGenericPropertiesOverridden() {
 				HikariDataSource ds = context.getBean(HikariDataSource.class);
 				assertThat(ds.getDataSourceProperties().getProperty("dataSourceClassName"))
 					.isEqualTo("org.h2.JDBCDataSource");
+			});
+	}
+
+	@Test
+	@SuppressWarnings("resource")
+	@ClassPathExclusions({ "h2-*.jar", "hsqldb-*.jar" })
+	void configureDataSourceClassNameWithNoEmbeddedDatabaseAvailable() {
+		this.contextRunner
+			.withPropertyValues("spring.datasource.url=jdbc:example//",
+					"spring.datasource.hikari.data-source-class-name=" + MockDataSource.class.getName())
+			.run((context) -> {
+				HikariDataSource ds = context.getBean(HikariDataSource.class);
+				assertThat(ds.getDataSourceClassName()).isEqualTo(MockDataSource.class.getName());
+				assertThatNoException().isThrownBy(() -> ds.getConnection().close());
+			});
+	}
 
+	@Test
+	@SuppressWarnings("resource")
+	void configureDataSourceClassNameToOverrideUseOfAnEmbeddedDatabase() {
+		this.contextRunner
+			.withPropertyValues("spring.datasource.url=jdbc:example//",
+					"spring.datasource.hikari.data-source-class-name=" + MockDataSource.class.getName())
+			.run((context) -> {
+				HikariDataSource ds = context.getBean(HikariDataSource.class);
+				assertThat(ds.getDataSourceClassName()).isEqualTo(MockDataSource.class.getName());
+				assertThatNoException().isThrownBy(() -> ds.getConnection().close());
 			});
 	}
 
@@ -201,4 +236,51 @@ DataSource dataSource() {
 
 	}
 
+	public static class MockDataSource implements DataSource {
+
+		@Override
+		public Logger getParentLogger() throws SQLFeatureNotSupportedException {
+			return null;
+		}
+
+		@Override
+		public <T> T unwrap(Class<T> iface) throws SQLException {
+			return null;
+		}
+
+		@Override
+		public boolean isWrapperFor(Class<?> iface) throws SQLException {
+			return false;
+		}
+
+		@Override
+		public Connection getConnection() throws SQLException {
+			return mock(Connection.class);
+		}
+
+		@Override
+		public Connection getConnection(String username, String password) throws SQLException {
+			return getConnection();
+		}
+
+		@Override
+		public PrintWriter getLogWriter() throws SQLException {
+			return null;
+		}
+
+		@Override
+		public void setLogWriter(PrintWriter out) throws SQLException {
+		}
+
+		@Override
+		public void setLoginTimeout(int seconds) throws SQLException {
+		}
+
+		@Override
+		public int getLoginTimeout() throws SQLException {
+			return -1;
+		}
+
+	}
+
 }