private ColumnMapping buildColumnMapping(Node column){
        Element column_ele = (Element)column;
        String src_name = column_ele.attributeValue("name");
        if(StringUtils.isBlank(src_name)){
            return null;
        }
        String tar_name = column_ele.attributeValue("tar-name");
        if(StringUtils.isBlank(tar_name)){
            tar_name = src_name;
        }
        ColumnMapping columnMapping = new ColumnMapping(src_name,tar_name);
        String type = column_ele.attributeValue("type");
        if(StringUtils.isNotBlank(type) && R.column.types.contains(type)){
            columnMapping.setType(type);
        }
        String data_type = column_ele.attributeValue("data-type");
        if(StringUtils.isNotBlank(type) && R.column.types.contains(type)){
            columnMapping.setData_type(data_type);
        }
        if(R.entity.type.add.equalsIgnoreCase(type)){
            Element value_ele = (Element)column_ele.selectSingleNode("value");
            columnMapping.setValue(ValueFactory.build(value_ele));
        }
        return columnMapping;
    }