mybatis报错：org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exception

2023年2月8日 264次阅读

接口配置：

package mybatis.mapper;

import java.util.List;

public interface TestMapper {
	public List<String> selectAllInfo();
}

mapper.xml配置：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" 
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="mybatis.mapper.TestMapper">

  <select id="selectAllInfo" resultType="java.util.List">
    SELECT
          ID
    FROM TEST
  </select>

</mapper>

在使用junit测试时出现以下错误：

org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: java.lang.UnsupportedOperationException
### The error may exist in mybatis/mapper/TestMapper.xml
### The error may involve defaultParameterMap
### The error occurred while setting parameters
### SQL: SELECT           ID     FROM TEST
### Cause: java.lang.UnsupportedOperationException

大致意思就是设置的参数有问题。

问题原因：

原因就在于mapper.xml的resultType代表的是List中的元素类型，而不应该是List本身，所以修改mapper.xml文件为：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" 
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="mybatis.mapper.TestMapper">

  <select id="selectAllInfo" resultType="java.lang.String">
    SELECT
          ID
    FROM TEST
  </select>

</mapper>

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