解决：org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.builder.BuilderException: Error evaluating expression 'requestMap.maintenancename != null and requestMap.maintenance

异常如下：org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.builder.BuilderException: Error evaluating expression 'requestMap.maintenancename != null and requestMap.maintenancename != '''. Cause: org.apache.ibatis.ognl.OgnlException: source is null for getProperty(null, "maintenancename")

解决方案：在dao层添加dao层方法中加@Param("requestmap")注解即可