IBatis Resultmap Error The error happened while setting a property on the result object solution

Error:
Org.springframework.jdbc.UncategorizedSQLException:SqlMapClient operation; Uncategorized SQLException for SQL [];

SQL state [NULL]; Error code [0];
---The error occurred in Com/sinosoft/para/conf/a_t_4_sqlmap.xml.
---The error occurred while applying a result map.
---Check the a_t_4.a_t_4result.
---The error happened while setting a property on the result object.
---Cause:net.sf.cglib.beans.BulkBeanException; Nested exception is

Com.ibatis.common.jdbc.exception.NestedSQLException:
---The error occurred in Com/sinosoft/para/conf/a_t_4_sqlmap.xml.
---The error occurred while applying a result map.
---Check the a_t_4.a_t_4result.
---The error happened while setting a property on the result object.

This error is a problem in Resultmap. Say that the error occurred when setting a property, but there is no specific description is a kind of error <null error >. Might just

is to assign a null value (double, and so on) to a column that is not NULL, so that you can modify it in Resultmap.
It must have been an exception when Ibatis tried to write null values read from the database to the object properties. The assignment of string type should be no problem, my database Also

There is a double type, and that is the problem, and the remedial measures taken are:
<result column= "rate" jdbctype= "DECIMAL" property= "rate" nullvalue= "0"/>
Null values read from the database are replaced by a value that can be converted to a decimal type or a double type.

Report:

Sqlmap:
<resultmap class= "Com.sinosoft.para.bean.A_t_4_6" id= "A_t_4_6result" >
<result property= "id" column= "user_id"/>
<result column= "rate" jdbctype= "DECIMAL" property= "rate" nullvalue= "0"/>
<!--this line plus a nullvalue= "0" is OK--

</resultMap>