Add domaCodeGen configuration for improved dependency management

Introduces a new Gradle configuration to allow users to specify JDBC drivers and other dependencies separately from their main project dependencies. This improves dependency isolation and makes it easier to configure the plugin without polluting the main classpath.

Changes:
- Add domaCodeGen configuration in CodeGenPlugin
- Update CodeGenConfig to use custom ClassLoader with configuration dependencies
- Enhance ClassUtil to support custom ClassLoader for class loading
- Update test project to use new configuration and runsql plugin for database setup

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

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

Author: nakamura-to

codegen-test/build.gradle.kts

@@ -1,6 +1,4 @@
-import org.h2.Driver
 import org.seasar.doma.gradle.codegen.desc.LanguageType
-import org.seasar.doma.gradle.codegen.jdbc.SimpleDataSource
 
 buildscript {
     repositories {
@@ -11,10 +9,7 @@ buildscript {
         }
     }
     dependencies {
-        val h2Version: String = properties["h2Version"] as String
         classpath("org.domaframework.doma:codegen")
-        classpath("com.h2database:h2:$h2Version")
-        classpath("mysql:mysql-connector-java:8.0.33")
     }
 }
 
@@ -23,6 +18,7 @@ plugins {
     id("org.jetbrains.kotlin.jvm") version "2.2.0"
     id("org.domaframework.doma.compile") version "4.0.0"
     id("org.domaframework.doma.codegen")
+    id("com.nocwriter.runsql") version "1.0.3"
 }
 
 java {
@@ -40,13 +36,19 @@ dependencies {
 
     implementation("org.seasar.doma:doma-core:$domaVersion")
     annotationProcessor("org.seasar.doma:doma-processor:$domaVersion")
-    
+
     // Use JUnit BOM for version management
     testImplementation(platform("org.junit:junit-bom:5.13.2"))
     testImplementation("org.junit.jupiter:junit-jupiter-api")
     testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine")
     testRuntimeOnly("org.junit.platform:junit-platform-launcher")
     testRuntimeOnly("com.h2database:h2:$h2Version")
+
+    // Add H2 to the domaCodeGen configuration
+    domaCodeGen("com.h2database:h2:$h2Version")
+
+    // Used by runsql-gradle-plugin
+    runtimeOnly("com.h2database:h2:$h2Version")
 }
 
 val _url = "jdbc:h2:file:$projectDir/data/db"
@@ -92,15 +94,13 @@ tasks {
         }
     }
 
-    val createDb = register("createDb") {
-        doLast {
-            val ds = SimpleDataSource()
-            ds.setDriver(Driver())
-            ds.setUrl(_url)
-            ds.setUser(_user)
-            ds.setPassword(_password)
-
-            val sql = """
+    val createDb = register<RunSQL>("createDb") {
+        config {
+            username = _user
+            password = _password
+            url = _url
+            driverClassName = "org.h2.Driver"
+            script = """
             drop all objects;
 
             create table department(
@@ -115,13 +115,8 @@ tasks {
                 employee_id integer not null primary key, 
                 employee_no integer not null,
                 employee_name varchar(20)
-            );
-            """
-            ds.connection.use {
-                it.createStatement().use {
-                    it.execute(sql)
-                }
-            }
+            );                
+            """.trimIndent()
         }
     }
 

codegen/src/main/java/org/seasar/doma/gradle/codegen/CodeGenPlugin.java

@@ -20,6 +20,7 @@
 public class CodeGenPlugin implements Plugin<Project> {
 
   public static final String EXTENSION_NAME = "domaCodeGen";
+  public static final String CONFIGURATION_NAME = "domaCodeGen";
   public static final String TASK_GROUP_NAME = "Doma Code Generation";
   public static final String DB_META_TASK_NAME = "DbMeta";
   public static final String DTO_TASK_NAME = "Dto";
@@ -33,6 +34,18 @@ public class CodeGenPlugin implements Plugin<Project> {
 
   @Override
   public void apply(Project project) {
+    project
+        .getConfigurations()
+        .create(
+            CONFIGURATION_NAME,
+            config -> {
+              config.setDescription(
+                  "The libraries used by the Doma CodeGen plugin for JDBC drivers and other dependencies");
+              config.setVisible(false);
+              config.setCanBeConsumed(false);
+              config.setCanBeResolved(true);
+            });
+
     NamedDomainObjectContainer<CodeGenConfig> container =
         project.container(
             CodeGenConfig.class,

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

@@ -1,14 +1,20 @@
 package org.seasar.doma.gradle.codegen.extension;
 
+import static org.seasar.doma.gradle.codegen.CodeGenPlugin.CONFIGURATION_NAME;
+
 import java.io.File;
+import java.net.URL;
+import java.net.URLClassLoader;
 import java.nio.charset.StandardCharsets;
 import java.sql.Driver;
 import java.util.Collections;
 import java.util.List;
+import java.util.Set;
 import javax.inject.Inject;
 import javax.sql.DataSource;
 import org.gradle.api.Action;
 import org.gradle.api.Project;
+import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.file.Directory;
 import org.gradle.api.file.DirectoryProperty;
 import org.gradle.api.file.FileTree;
@@ -31,6 +37,8 @@ public class CodeGenConfig {
 
   private final String name;
 
+  private final Configuration configuration;
+
   private final Property<GlobalFactory> globalFactory;
 
   private final Property<DataSource> dataSource;
@@ -85,6 +93,8 @@ public class CodeGenConfig {
   public CodeGenConfig(String name, Project project) {
     this.name = name;
 
+    this.configuration = project.getConfigurations().getByName(CONFIGURATION_NAME);
+
     ObjectFactory objects = project.getObjects();
 
     globalFactory = objects.property(GlobalFactory.class);
@@ -146,13 +156,32 @@ private Provider<DataSource> dataSourceProvider() {
           if (driverClassName == null) {
             throw new CodeGenException(Message.DOMAGEN0024);
           }
-          Driver driver = ClassUtil.newInstance(Driver.class, driverClassName, "driverClassName");
+          ClassLoader classLoader = createClassLoader();
+          Driver driver =
+              ClassUtil.newInstance(Driver.class, driverClassName, "driverClassName", classLoader);
           return globalFactory
               .get()
               .createDataSource(driver, user.getOrNull(), password.getOrNull(), url.get());
         });
   }
 
+  protected ClassLoader createClassLoader() {
+    if (configuration == null || configuration.isEmpty()) {
+      return getClass().getClassLoader();
+    }
+    Set<File> fileSet = configuration.getFiles();
+    URL[] urls = new URL[fileSet.size()];
+    int i = 0;
+    for (File file : fileSet) {
+      try {
+        urls[i++] = file.toURI().toURL();
+      } catch (Exception e) {
+        throw new RuntimeException("Failed to convert file to URL: " + file, e);
+      }
+    }
+    return new URLClassLoader(urls, getClass().getClassLoader());
+  }
+
   private Provider<CodeGenDialect> codeGenDialectProvider() {
     return url.map(
         it -> {

codegen/src/main/java/org/seasar/doma/gradle/codegen/util/ClassUtil.java

@@ -57,7 +57,13 @@ public static Class<?> toBoxedPrimitiveTypeIfPossible(Class<?> clazz) {
 
   public static <T> T newInstance(Class<T> supertype, String className, String propertyName) {
     AssertionUtil.assertNotNull(supertype, className, propertyName);
-    Class<?> clazz = forName(className, propertyName);
+    return newInstance(supertype, className, propertyName, null);
+  }
+
+  public static <T> T newInstance(
+      Class<T> supertype, String className, String propertyName, ClassLoader classLoader) {
+    AssertionUtil.assertNotNull(supertype, className, propertyName);
+    Class<?> clazz = forName(className, propertyName, classLoader);
     if (!supertype.isAssignableFrom(clazz)) {
       throw new CodeGenException(Message.DOMAGEN0014, propertyName, className, supertype.getName());
     }
@@ -69,9 +75,18 @@ public static <T> T newInstance(Class<T> supertype, String className, String pro
   }
 
   public static Class<?> forName(String className, String propertyName) {
+    AssertionUtil.assertNotNull(className, propertyName);
+    return forName(className, propertyName, null);
+  }
+
+  public static Class<?> forName(String className, String propertyName, ClassLoader classLoader) {
     AssertionUtil.assertNotNull(className, propertyName);
     try {
-      return Class.forName(className);
+      if (classLoader != null) {
+        return classLoader.loadClass(className);
+      } else {
+        return Class.forName(className);
+      }
     } catch (ClassNotFoundException e) {
       throw new CodeGenException(Message.DOMAGEN0013, propertyName, className, e);
     }