1、 Questions
Malformed ognl expression: name! = null and name! = ‘
report an error;
malformed means abnormal;
2、 Solutions and reasons
It turned out to be* Mapper.xml In the document:
<if test ="userId ! null">
The equals sign is missing; the SQL in the automatically generated mybatis file is missing an equals sign
<if test ="userId != null">
Moreover, there should be no space between exclamation mark and equal sign;