give TypeHandler a chance to get class type

src/main/java/org/apache/ibatis/executor/result/ResultClassTypeHolder.java

@@ -0,0 +1,19 @@
+package org.apache.ibatis.executor.result;
+
+public class ResultClassTypeHolder {
+
+  // hold the the class type of result
+  private static final ThreadLocal<Class> resultTypeTl = new ThreadLocal();
+
+  public static void setResultType(Class clazz) {
+    resultTypeTl.set(clazz);
+  }
+
+  public static Class getResultType() {
+    return resultTypeTl.get();
+  }
+
+  public static void clean() {
+    resultTypeTl.remove();
+  }
+}

src/main/java/org/apache/ibatis/executor/resultset/DefaultResultSetHandler.java

@@ -41,6 +41,7 @@
 import org.apache.ibatis.executor.parameter.ParameterHandler;
 import org.apache.ibatis.executor.result.DefaultResultContext;
 import org.apache.ibatis.executor.result.DefaultResultHandler;
+import org.apache.ibatis.executor.result.ResultClassTypeHolder;
 import org.apache.ibatis.executor.result.ResultMapException;
 import org.apache.ibatis.mapping.BoundSql;
 import org.apache.ibatis.mapping.Discriminator;
@@ -293,6 +294,7 @@ private void validateResultMapsCount(ResultSetWrapper rsw, int resultMapCount) {
 
   private void handleResultSet(ResultSetWrapper rsw, ResultMap resultMap, List<Object> multipleResults, ResultMapping parentMapping) throws SQLException {
     try {
+      ResultClassTypeHolder.setResultType(resultMap.getType());
       if (parentMapping != null) {
         handleRowValues(rsw, resultMap, null, RowBounds.DEFAULT, parentMapping);
       } else {
@@ -307,6 +309,7 @@ private void handleResultSet(ResultSetWrapper rsw, ResultMap resultMap, List<Obj
     } finally {
       // issue #228 (close resultsets)
       closeResultSet(rsw.getResultSet());
+      ResultClassTypeHolder.clean();
     }
   }