Cause: java.lang.NullPointerException: target is null for method size
org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException:
### Error querying database. Cause: java.lang.NullPointerException: target is null for method size
### Cause: java.lang.NullPointerException: target is null for method size
at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:77)
at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:446报错信息是因为xxxMapper.xml文件sql写的有问题 -- <if test="">....</if> test条件未对集合进行判空处理,如果集合为null会报上述错误
修改也很简单，加上判空处理,示例如下：
<if test="collection != null and collection.size() > 0 ">
and xxxx in
<foreach collection="collection" close=")" open="(" item="item" separator=",">
#{item}
</foreach>
</if>说明：test="collection ..." 这里的collection是dao传进来的集合名，可以自定义
----------------------------- 分割符 -------------------------------
xxx no getter method ....
如果入参实体中没有xxx属性，而xxxMapper.xml中<if test= "xxx != null"> 此时会报 no getter method 错误，修改也很简单，
方法一删除xml中对应的<if>标签
方法二 入参实体中加上xxx属性
