Merge pull request #39376 from ronaldmik

* gh-39376:
  Polish "Derive driverClassName from URL when otherwise unknown"
  Derive driverClassName from URL when otherwise unknown

Closes gh-39376

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

@@ -186,8 +186,8 @@ public final class DataSourceBuilder<T extends DataSource> {
 		}
 		if (!applied.contains(DataSourceProperty.DRIVER_CLASS_NAME)
 				&& properties.canSet(DataSourceProperty.DRIVER_CLASS_NAME)
-				&& this.values.containsKey(DataSourceProperty.URL)) {
-			String url = this.values.get(DataSourceProperty.URL);
+				&& applied.contains(DataSourceProperty.URL)) {
+			String url = properties.get(dataSource, DataSourceProperty.URL);
 			DatabaseDriver driver = DatabaseDriver.fromJdbcUrl(url);
 			properties.set(dataSource, DataSourceProperty.DRIVER_CLASS_NAME, driver.getDriverClassName());
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -457,6 +457,36 @@ class DataSourceBuilderTests {
 		assertThat(testSource.getPassword()).isEqualTo("secret");
 	}
 
+	@Test
+	void buildWhenDerivedFromCustomTypeDeriveDriverClassNameFromUrl() {
+		NoDriverClassNameDataSource dataSource = new NoDriverClassNameDataSource();
+		dataSource.setUsername("test");
+		dataSource.setPassword("secret");
+		dataSource.setUrl("jdbc:postgresql://localhost:5432/postgres");
+		DataSourceBuilder<?> builder = DataSourceBuilder.derivedFrom(dataSource).type(SimpleDriverDataSource.class);
+		SimpleDriverDataSource testSource = (SimpleDriverDataSource) builder.build();
+		assertThat(testSource.getUsername()).isEqualTo("test");
+		assertThat(testSource.getUrl()).isEqualTo("jdbc:postgresql://localhost:5432/postgres");
+		assertThat(testSource.getPassword()).isEqualTo("secret");
+		assertThat(testSource.getDriver()).isInstanceOf(org.postgresql.Driver.class);
+	}
+
+	@Test
+	void buildWhenDerivedFromCustomTypeDeriveDriverClassNameFromOverridenUrl() {
+		NoDriverClassNameDataSource dataSource = new NoDriverClassNameDataSource();
+		dataSource.setUsername("test");
+		dataSource.setPassword("secret");
+		dataSource.setUrl("jdbc:mysql://localhost:5432/mysql");
+		DataSourceBuilder<?> builder = DataSourceBuilder.derivedFrom(dataSource)
+			.type(SimpleDriverDataSource.class)
+			.url("jdbc:mariadb://localhost:5432/mariadb");
+		SimpleDriverDataSource testSource = (SimpleDriverDataSource) builder.build();
+		assertThat(testSource.getUsername()).isEqualTo("test");
+		assertThat(testSource.getUrl()).isEqualTo("jdbc:mariadb://localhost:5432/mariadb");
+		assertThat(testSource.getPassword()).isEqualTo("secret");
+		assertThat(testSource.getDriver()).isInstanceOf(org.mariadb.jdbc.Driver.class);
+	}
+
 	@Test // gh-31920
 	void buildWhenC3P0TypeSpecifiedReturnsExpectedDataSource() {
 		this.dataSource = DataSourceBuilder.create()
@@ -620,12 +650,10 @@ class DataSourceBuilderTests {
 
 	}
 
-	static class CustomDataSource extends LimitedCustomDataSource {
+	static class NoDriverClassNameDataSource extends LimitedCustomDataSource {
 
 		private String url;
 
-		private String driverClassName;
-
 		String getUrl() {
 			return this.url;
 		}
@@ -634,6 +662,14 @@ class DataSourceBuilderTests {
 			this.url = url;
 		}
 
+	}
+
+	static class CustomDataSource extends LimitedCustomDataSource {
+
+		private String driverClassName;
+
+		private String url;
+
 		String getDriverClassName() {
 			return this.driverClassName;
 		}
@@ -642,6 +678,14 @@ class DataSourceBuilderTests {
 			this.driverClassName = driverClassName;
 		}
 
+		String getUrl() {
+			return this.url;
+		}
+
+		void setUrl(String url) {
+			this.url = url;
+		}
+
 	}
 
 }