org.apache.commons.lang3.tuple.Pair 作为更新参数，XML 中的 Sql 取不到值、报错

项目用的 Mybatis，今天改一个需求，落地实现是批量更新，且只需要根据主键(id)来更新一个字段(name)。

于是，没有犹豫，像下面这样设计了数据结构：

既然是批量更新，那外层肯定是 List
List 中每个元素，只包含 id & name，于是，选择了用 org.apache.commons.lang3.tuple.Pair 来封装数据（就是不想自己再写一个 DO 或者 VO 或者 MO）
最终的数据结构是：List<Pair<Integer, String>>

XML 中的 Sql 语句，很简单，如下：

    <update id="updateByApacheCommonsPair">

        <foreach collection="list" separator=";" item="x">

            UPDATE employee SET name = #{x.right} WHERE id = #{x.left}

        </foreach>

    </update>

提示：XML 中的 Sql 引入了一个名为 x 的变量（后面会用到）

一切顺利，但测试时，报错如下：

org.apache.ibatis.exceptions.PersistenceException:

### Error updating database.  Cause: org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'right' in 'class java.lang.String'

### The error may involve defaultParameterMap

### The error occurred while setting parameters

### SQL: UPDATE employee SET name = ? WHERE id = ?

### Cause: org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'right' in 'class java.lang.String'

    at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)

    at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:200)

    at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:62)

    at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:53)

    at com.sun.proxy.$Proxy4.updateByApacheCommonsPair(Unknown Source)

    at com.atguigu.mybatis.test.MyBatisTest.testUpdateByApacheCommonsPair(MyBatisTest.java:42)

    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

    at java.lang.reflect.Method.invoke(Method.java:498)

    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)

    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)

    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)

    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)

    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)

    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)

    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)

    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)

    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)

    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)

    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)

    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)

    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)

    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)

    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)

    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)

    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)

    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

Caused by: org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'right' in 'class java.lang.String'

    at org.apache.ibatis.reflection.Reflector.getGetInvoker(Reflector.java:409)

    at org.apache.ibatis.reflection.MetaClass.getGetInvoker(MetaClass.java:164)

    at org.apache.ibatis.reflection.wrapper.BeanWrapper.getBeanProperty(BeanWrapper.java:162)

    at org.apache.ibatis.reflection.wrapper.BeanWrapper.get(BeanWrapper.java:49)

    at org.apache.ibatis.reflection.MetaObject.getValue(MetaObject.java:122)

    at org.apache.ibatis.reflection.MetaObject.getValue(MetaObject.java:119)

    at org.apache.ibatis.mapping.BoundSql.getAdditionalParameter(BoundSql.java:75)

    at org.apache.ibatis.scripting.defaults.DefaultParameterHandler.setParameters(DefaultParameterHandler.java:72)

    at org.apache.ibatis.executor.statement.PreparedStatementHandler.parameterize(PreparedStatementHandler.java:93)

    at org.apache.ibatis.executor.statement.RoutingStatementHandler.parameterize(RoutingStatementHandler.java:64)

    at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:86)

    at org.apache.ibatis.executor.SimpleExecutor.doUpdate(SimpleExecutor.java:49)

    at org.apache.ibatis.executor.BaseExecutor.update(BaseExecutor.java:117)

    at org.apache.ibatis.executor.CachingExecutor.update(CachingExecutor.java:76)

    at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:198)

    ... 26 more