Fix class loader issues with JDBC drivers

Wrap JDBC drivers to ensure proper class loader context switching when
executing driver operations. This prevents ClassNotFoundException and
other class loading issues when the driver and plugin are loaded by
different class loaders.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: nakamura-to

codegen/src/main/java/org/seasar/doma/gradle/codegen/extension/CodeGenConfig.java

@@ -29,6 +29,7 @@
 import org.seasar.doma.gradle.codegen.dialect.CodeGenDialectRegistry;
 import org.seasar.doma.gradle.codegen.exception.CodeGenException;
 import org.seasar.doma.gradle.codegen.generator.Generator;
+import org.seasar.doma.gradle.codegen.jdbc.DriverWrapper;
 import org.seasar.doma.gradle.codegen.message.Message;
 import org.seasar.doma.gradle.codegen.util.ClassUtil;
 import org.seasar.doma.gradle.codegen.util.JdbcUtil;
@@ -159,9 +160,10 @@ private Provider<DataSource> dataSourceProvider() {
           ClassLoader classLoader = createClassLoader();
           Driver driver =
               ClassUtil.newInstance(Driver.class, driverClassName, "driverClassName", classLoader);
+          DriverWrapper driverWrapper = new DriverWrapper(driver);
           return globalFactory
               .get()
-              .createDataSource(driver, user.getOrNull(), password.getOrNull(), url.get());
+              .createDataSource(driverWrapper, user.getOrNull(), password.getOrNull(), url.get());
         });
   }
 

codegen/src/main/java/org/seasar/doma/gradle/codegen/jdbc/DriverWrapper.java

@@ -0,0 +1,143 @@
+package org.seasar.doma.gradle.codegen.jdbc;
+
+import java.sql.Connection;
+import java.sql.Driver;
+import java.sql.DriverPropertyInfo;
+import java.sql.SQLException;
+import java.sql.SQLFeatureNotSupportedException;
+import java.util.Objects;
+import java.util.Properties;
+import java.util.logging.Logger;
+
+/**
+ * A wrapper for JDBC Driver that manages class loader context switching.
+ *
+ * <p>This wrapper ensures that all driver operations are executed with the correct class loader
+ * context, preventing class loading issues when the driver and calling code are loaded by different
+ * class loaders.
+ *
+ * @see java.sql.Driver
+ */
+public class DriverWrapper implements Driver {
+
+  private final Driver driver;
+
+  /**
+   * Constructs a new DriverWrapper with the specified driver.
+   *
+   * @param driver the driver to wrap, must not be null
+   * @throws NullPointerException if driver is null
+   */
+  public DriverWrapper(Driver driver) {
+    this.driver = Objects.requireNonNull(driver);
+  }
+
+  /**
+   * {@inheritDoc}
+   *
+   * <p>Executes with the driver's class loader context.
+   */
+  @Override
+  public Connection connect(String url, Properties info) throws SQLException {
+    return execute(() -> driver.connect(url, info));
+  }
+
+  /**
+   * {@inheritDoc}
+   *
+   * <p>Executes with the driver's class loader context.
+   */
+  @Override
+  public boolean acceptsURL(String url) throws SQLException {
+    return execute(() -> driver.acceptsURL(url));
+  }
+
+  /**
+   * {@inheritDoc}
+   *
+   * <p>Executes with the driver's class loader context.
+   */
+  @Override
+  public DriverPropertyInfo[] getPropertyInfo(String url, Properties info) throws SQLException {
+    return execute(() -> driver.getPropertyInfo(url, info));
+  }
+
+  /**
+   * {@inheritDoc}
+   *
+   * <p>Executes with the driver's class loader context.
+   */
+  @Override
+  public int getMajorVersion() {
+    return execute(driver::getMajorVersion);
+  }
+
+  /**
+   * {@inheritDoc}
+   *
+   * <p>Executes with the driver's class loader context.
+   */
+  @Override
+  public int getMinorVersion() {
+    return execute(driver::getMinorVersion);
+  }
+
+  /**
+   * {@inheritDoc}
+   *
+   * <p>Executes with the driver's class loader context.
+   */
+  @Override
+  public boolean jdbcCompliant() {
+    return execute(driver::jdbcCompliant);
+  }
+
+  /**
+   * {@inheritDoc}
+   *
+   * <p>Executes with the driver's class loader context.
+   */
+  @Override
+  public Logger getParentLogger() throws SQLFeatureNotSupportedException {
+    return execute(driver::getParentLogger);
+  }
+
+  /**
+   * Executes an operation with the driver's class loader as the context class loader.
+   *
+   * <p>This method temporarily switches the thread's context class loader to the driver's class
+   * loader, executes the operation, and then restores the original class loader. This ensures that
+   * the driver can properly load its internal classes and resources.
+   *
+   * @param <R> the return type of the executable
+   * @param <TH> the type of exception that may be thrown
+   * @param executable the operation to execute
+   * @return the result of the executable operation
+   * @throws TH if the executable operation throws an exception
+   */
+  private <R, TH extends Exception> R execute(Executable<R, TH> executable) throws TH {
+    var classLoader = Thread.currentThread().getContextClassLoader();
+    Thread.currentThread().setContextClassLoader(driver.getClass().getClassLoader());
+    try {
+      return executable.execute();
+    } finally {
+      Thread.currentThread().setContextClassLoader(classLoader);
+    }
+  }
+
+  /**
+   * Represents an executable operation that can return a result and throw an exception.
+   *
+   * @param <R> the return type
+   * @param <TH> the type of exception that may be thrown
+   */
+  private interface Executable<R, TH extends Exception> {
+    /**
+     * Executes the operation.
+     *
+     * @return the result of the operation
+     * @throws TH if an error occurs during execution
+     */
+    R execute() throws TH;
+  }
+}