Merge pull request #2727 from epochcoder/feature/2724-pass-subclassed-configuration-xmlconfigbuilder

Enable ability to provide custom configuration to XMLConfigBuilder

Author: harawata

src/main/java/org/apache/ibatis/builder/xml/XMLConfigBuilder.java

@@ -67,7 +67,11 @@ public XMLConfigBuilder(Reader reader, String environment) {
   }
 
   public XMLConfigBuilder(Reader reader, String environment, Properties props) {
-    this(new XPathParser(reader, true, props, new XMLMapperEntityResolver()), environment, props);
+    this(Configuration.class, reader, environment, props);
+  }
+
+  public XMLConfigBuilder(Class<? extends Configuration> configClass, Reader reader, String environment, Properties props) {
+    this(configClass, new XPathParser(reader, true, props, new XMLMapperEntityResolver()), environment, props);
   }
 
   public XMLConfigBuilder(InputStream inputStream) {
@@ -79,11 +83,15 @@ public XMLConfigBuilder(InputStream inputStream, String environment) {
   }
 
   public XMLConfigBuilder(InputStream inputStream, String environment, Properties props) {
-    this(new XPathParser(inputStream, true, props, new XMLMapperEntityResolver()), environment, props);
+    this(Configuration.class, inputStream, environment, props);
+  }
+
+  public XMLConfigBuilder(Class<? extends Configuration> configClass, InputStream inputStream, String environment, Properties props) {
+    this(configClass, new XPathParser(inputStream, true, props, new XMLMapperEntityResolver()), environment, props);
   }
 
-  private XMLConfigBuilder(XPathParser parser, String environment, Properties props) {
-    super(new Configuration());
+  private XMLConfigBuilder(Class<? extends Configuration> configClass, XPathParser parser, String environment, Properties props) {
+    super(newConfig(configClass));
     ErrorContext.instance().resource("SQL Mapper Configuration");
     this.configuration.setVariables(props);
     this.parsed = false;
@@ -406,4 +414,12 @@ private boolean isSpecifiedEnvironment(String id) {
     return environment.equals(id);
   }
 
+  private static Configuration newConfig(Class<? extends Configuration> configClass) {
+    try {
+      return configClass.getDeclaredConstructor().newInstance();
+    } catch (Exception ex) {
+      throw new BuilderException("Failed to create a new Configuration instance.", ex);
+    }
+  }
+
 }

src/test/java/org/apache/ibatis/builder/XmlConfigBuilderTest.java

@@ -19,10 +19,12 @@
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.BDDAssertions.then;
 import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import java.io.IOException;
 import java.io.InputStream;
 import java.io.StringReader;
 import java.math.RoundingMode;
@@ -64,6 +66,7 @@
 import org.apache.ibatis.type.JdbcType;
 import org.apache.ibatis.type.TypeHandler;
 import org.apache.ibatis.type.TypeHandlerRegistry;
+import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Tag;
 import org.junit.jupiter.api.Test;
 
@@ -114,7 +117,7 @@ enum MyEnum {
 
   public static class EnumOrderTypeHandler<E extends Enum<E>> extends BaseTypeHandler<E> {
 
-    private E[] constants;
+    private final E[] constants;
 
     public EnumOrderTypeHandler(Class<E> javaType) {
       constants = javaType.getEnumConstants();
@@ -319,4 +322,37 @@ public static String provideSql() {
     }
   }
 
+  @Test
+  void shouldAllowSubclassedConfiguration() throws IOException {
+    String resource = "org/apache/ibatis/builder/MinimalMapperConfig.xml";
+    try (InputStream inputStream = Resources.getResourceAsStream(resource)) {
+      XMLConfigBuilder builder = new XMLConfigBuilder(
+              MyConfiguration.class, inputStream, null, null);
+      Configuration config = builder.parse();
+
+      assertThat(config).isInstanceOf(MyConfiguration.class);
+    }
+  }
+
+  @Test
+  void noDefaultConstructorForSubclassedConfiguration() throws IOException {
+    String resource = "org/apache/ibatis/builder/MinimalMapperConfig.xml";
+    try (InputStream inputStream = Resources.getResourceAsStream(resource)) {
+      Exception exception = Assertions.assertThrows(Exception.class, () -> new XMLConfigBuilder(
+              BadConfiguration.class, inputStream, null, null));
+      assertEquals("Failed to create a new Configuration instance.", exception.getMessage());
+    }
+  }
+
+  public static class MyConfiguration extends Configuration {
+    // only using to check configuration was used
+  }
+
+  public static class BadConfiguration extends Configuration {
+
+    public BadConfiguration(String parameter) {
+        // should have a default constructor
+    }
+  }
+
 }