如何使用MyBatis从BYtea列中获取byte []? [英] How can I get byte[] from bytea column with MyBatis?

问题描述

我尝试了以下方法.

这是查询映射:

<select id="getTypicalTaskMeasurementParameterValue" 
            parameterType="Integer" 
            resultType="byte[]">
    SELECT value 
    FROM typical_task_measurements_parameter_values 
    WHERE id_typical_task_measurement = #{typicalTaskMeasurementId}
</select>

这是方法:

public byte[] getTypicalTaskMeasurementParameterValue(
    Integer typicalTaskMeasurementId);

这是我尝试对它运行单元测试时遇到的错误:

And here is the error I got, trying to run the unit test against it:

nested exception is org.apache.ibatis.reflection.ReflectionException: 
Error instantiating class [Ljava.lang.Byte; with invalid types () or values (). 
Cause: java.lang.NoSuchMethodException: [Ljava.lang.Byte;.<init>()
at ...

此外，此bytea员工的设置方法还可以.

Moreover, setter method for this bytea staff is ok.

推荐答案

该错误消息很好地说明了问题. java.lang.Byte上没有默认构造函数.

The error message says the problem pretty well. There is no default constructor on java.lang.Byte.

您需要一个结果图，该结果图将选择要使用的构造函数，或实现自己的TypeHandler.

You need a result map that will choose which constructor to use, or implement your own TypeHandler.

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