Refactor the columnar related code (#1696)

- Refactor ColumnarData and ColumnarDataBuilder.
- Remove redundant code.

Fixes #1698

Signed-off-by: vegetableysm <[email protected]>

java/modules/basic/src/main/java/io/v6d/modules/basic/columnar/ArrowFieldVectorAccessor.java

@@ -0,0 +1,61 @@
+/** Copyright 2020-2023 Alibaba Group Holding Limited.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.v6d.modules.basic.columnar;
+
+import org.apache.arrow.vector.FieldVector;
+
+class ArrowFieldVectorAccessor {
+    public final FieldVector accessor;
+
+    ArrowFieldVectorAccessor(FieldVector vector) {
+        this.accessor = vector;
+    }
+
+    public final FieldVector getVector() {
+        return accessor;
+    }
+
+    final boolean isNullAt(int rowId) {
+        return accessor.isNull(rowId);
+    }
+
+    final int getNullCount() {
+        return accessor.getNullCount();
+    }
+
+    final int getValueCount() {
+        return accessor.getValueCount();
+    }
+
+    final void close() {
+        accessor.close();
+    }
+
+    Object getObject(int rowId) {
+        throw new UnsupportedOperationException();
+    }
+
+    void setSafe(int rowId, Object value) {
+        if (value == null) {
+            this.accessor.setNull(rowId);
+        } else {
+            this.setObject(rowId, value);
+        }
+    }
+
+    void setObject(int rowId, Object value) {
+        throw new UnsupportedOperationException();
+    }
+}