src/main/java/com/itfsw/mybatis/generator/plugins/utils/XmlElementGeneratorTools.java
private static void generateSelectiveToTrimEleTo(XmlElement trimEle, IntrospectedColumn introspectedColumn, String prefix, int type) {
        if (type != 3 && (introspectedColumn.isSequenceColumn() || introspectedColumn.getFullyQualifiedJavaType().isPrimitive())) {
            // if it is a sequence column, it is not optional
            // This is required for MyBatis3 because MyBatis3 parses
            // and calculates the SQL before executing the selectKey

            // if it is primitive, we cannot do a null check
            generateSelectiveCommColumnTo(trimEle, introspectedColumn, prefix, type);
        } else {
            XmlElement eleIf = new XmlElement("if");
            eleIf.addAttribute(new Attribute("test", introspectedColumn.getJavaProperty(prefix) + " != null"));

            generateSelectiveCommColumnTo(eleIf, introspectedColumn, prefix, type);

            trimEle.addElement(eleIf);
        }
    }
private static void generateSelectiveToTrimEleTo(XmlElement trimEle, IntrospectedColumn introspectedColumn, String prefix, int type) {
        if (type != 3 && (introspectedColumn.isSequenceColumn() || introspectedColumn.getFullyQualifiedJavaType().isPrimitive())) {
            // if it is a sequence column, it is not optional
            // This is required for MyBatis3 because MyBatis3 parses
            // and calculates the SQL before executing the selectKey

            // if it is primitive, we cannot do a null check
            generateSelectiveCommColumnTo(trimEle, introspectedColumn, prefix, type);
        } else {
            XmlElement eleIf = new XmlElement("if");
            eleIf.addAttribute(new Attribute("test", introspectedColumn.getJavaProperty(prefix) + " != null"));

            generateSelectiveCommColumnTo(eleIf, introspectedColumn, prefix, type);

            trimEle.addElement(eleIf);
        }
    }
生成选择列到trim 节点
@param trimEle
@param introspectedColumn
@param prefix
@param type               1:key,2:value,3:set