Restore support for C3P0

Closes gh-31920

Author: snicoll

Diff for: spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jdbc/DataSourceAutoConfigurationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 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.
@@ -253,7 +253,7 @@ void whenNoInitializationRelatedSpringDataSourcePropertiesAreConfiguredThenIniti
 
 	private static Function<ApplicationContextRunner, ApplicationContextRunner> hideConnectionPools() {
 		return (runner) -> runner.withClassLoader(new FilteredClassLoader("org.apache.tomcat", "com.zaxxer.hikari",
-				"org.apache.commons.dbcp2", "oracle.ucp.jdbc"));
+				"org.apache.commons.dbcp2", "oracle.ucp.jdbc", "com.mchange"));
 	}
 
 	private <T extends DataSource> void assertDataSource(Class<T> expectedType, List<String> hiddenPackages,

Diff for: spring-boot-project/spring-boot-docs/src/docs/asciidoc/data/sql.adoc

@@ -135,6 +135,7 @@ The following connection pools are supported by `DataSourceBuilder`:
 * Spring Framework's `SimpleDriverDataSource`
 * H2 `JdbcDataSource`
 * PostgreSQL `PGSimpleDataSource`
+* C3P0
 
 
 

Diff for: spring-boot-project/spring-boot-parent/build.gradle

@@ -27,6 +27,13 @@ bom {
 			]
 		}
 	}
+	library("C3P0", "0.9.5.5") {
+		group("com.mchange") {
+			modules = [
+					"c3p0"
+			]
+		}
+	}
 	library("Commons Compress", "1.21") {
 		group("org.apache.commons") {
 			modules = [

Diff for: spring-boot-project/spring-boot/build.gradle

@@ -28,6 +28,7 @@ dependencies {
 	optional("com.fasterxml.jackson.core:jackson-databind")
 	optional("com.h2database:h2")
 	optional("com.google.code.gson:gson")
+	optional("com.mchange:c3p0")
 	optional("com.oracle.database.jdbc:ucp")
 	optional("com.oracle.database.jdbc:ojdbc8")
 	optional("com.samskivert:jmustache")

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

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.jdbc;
 
+import java.beans.PropertyVetoException;
 import java.lang.reflect.Method;
 import java.sql.SQLException;
 import java.util.Collections;
@@ -27,6 +28,7 @@
 
 import javax.sql.DataSource;
 
+import com.mchange.v2.c3p0.ComboPooledDataSource;
 import com.zaxxer.hikari.HikariDataSource;
 import oracle.jdbc.datasource.OracleDataSource;
 import oracle.ucp.jdbc.PoolDataSource;
@@ -391,6 +393,8 @@ private static <T extends DataSource> MappedDataSourceProperties<T> lookupPooled
 					MappedDbcp2DataSource::new);
 			result = lookup(classLoader, type, result, "oracle.ucp.jdbc.PoolDataSourceImpl",
 					OraclePoolDataSourceProperties::new, "oracle.jdbc.OracleConnection");
+			result = lookup(classLoader, type, result, "com.mchange.v2.c3p0.ComboPooledDataSource",
+					ComboPooledDataSourceProperties::new);
 			return result;
 		}
 
@@ -650,6 +654,29 @@ public Class<? extends PoolDataSource> getDataSourceInstanceType() {
 
 	}
 
+	/**
+	 * {@link DataSourceProperties} for C3P0.
+	 */
+	private static class ComboPooledDataSourceProperties extends MappedDataSourceProperties<ComboPooledDataSource> {
+
+		ComboPooledDataSourceProperties() {
+			add(DataSourceProperty.URL, ComboPooledDataSource::getJdbcUrl, ComboPooledDataSource::setJdbcUrl);
+			add(DataSourceProperty.DRIVER_CLASS_NAME, ComboPooledDataSource::getDriverClass, this::setDriverClass);
+			add(DataSourceProperty.USERNAME, ComboPooledDataSource::getUser, ComboPooledDataSource::setUser);
+			add(DataSourceProperty.PASSWORD, ComboPooledDataSource::getPassword, ComboPooledDataSource::setPassword);
+		}
+
+		private void setDriverClass(ComboPooledDataSource dataSource, String driverClass) {
+			try {
+				dataSource.setDriverClass(driverClass);
+			}
+			catch (PropertyVetoException ex) {
+				throw new IllegalArgumentException(ex);
+			}
+		}
+
+	}
+
 	/**
 	 * {@link DataSourceProperties} for Spring's {@link SimpleDriverDataSource}.
 	 */

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

@@ -26,6 +26,7 @@
 
 import javax.sql.DataSource;
 
+import com.mchange.v2.c3p0.ComboPooledDataSource;
 import com.microsoft.sqlserver.jdbc.SQLServerDataSource;
 import com.zaxxer.hikari.HikariDataSource;
 import oracle.jdbc.internal.OpaqueString;
@@ -384,6 +385,19 @@ void buildWhenDerivedFromCustomTypeWithTypeChange() {
 		assertThat(testSource.getPassword()).isEqualTo("secret");
 	}
 
+	@Test // gh-31920
+	void buildWhenC3P0TypeSpecifiedReturnsExpectedDataSource() {
+		this.dataSource = DataSourceBuilder.create().url("jdbc:postgresql://localhost:5432/postgres")
+				.type(ComboPooledDataSource.class).username("test").password("secret")
+				.driverClassName("com.example.Driver").build();
+		assertThat(this.dataSource).isInstanceOf(ComboPooledDataSource.class);
+		ComboPooledDataSource c3p0DataSource = (ComboPooledDataSource) this.dataSource;
+		assertThat(c3p0DataSource.getJdbcUrl()).isEqualTo("jdbc:postgresql://localhost:5432/postgres");
+		assertThat(c3p0DataSource.getUser()).isEqualTo("test");
+		assertThat(c3p0DataSource.getPassword()).isEqualTo("secret");
+		assertThat(c3p0DataSource.getDriverClass()).isEqualTo("com.example.Driver");
+	}
+
 	final class HidePackagesClassLoader extends URLClassLoader {
 
 		private final String[] hiddenPackages;