mybatis----mapper返回值为map时，只能有一行返回值，多了会报错

最新推荐文章于 2024-12-09 09:16:43 发布

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最新推荐文章于 2024-12-09 09:16:43 发布

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文章标签： sql mybatis

本文链接：https://blog.youkuaiyun.com/m0_49665279/article/details/122913742

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以map为返回值时，该行的行名为key值，每列的值value

接口文件：
package org.example.dao;

import org.example.tables.users;

import java.util.List;
import java.util.Map;

/**
 * @author xujun
 * @date2022/2/9 13:52
 * @Description TODO
 * apiNote
 */
public interface usersdao {
   
    Map<Object,Object> selectusersMap();
}
mapper配置文件：
<?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="org.example.dao.usersdao">
 
    <select id="selectusersMap" resultType="map" >
        select * from users
    </select>

</mapper>
java测试文件：
@Test
public void testselectusersMap(){
    SqlSession sqlSession=MybatisUtils.getSqlSession();
    usersdao usersdao=sqlSession.getMapper(usersdao.class);
    Map<Object,Object> result=usersdao.selectusersMap();

    for(Map.Entry<Object,Object>  re:result.entrySet()){
        Object key=re.getKey();
        Object value=re.getValue();
        System.out.println(value);
    }

    sqlSession.close();
}
错误：

org.apache.ibatis.exceptions.TooManyResultsException: Expected one result (or null) to be returned by selectOne(), but found: 15

   at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:80)
   at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:87)
   at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:57)
   at jdk.proxy2/jdk.proxy2.$Proxy4.selectusersMap(Unknown Source)
   at org.example.TestUserdaoimpl.testselectusersMap(TestUserdaoimpl.java:89)
   at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78)
   at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
   at java.base/java.lang.reflect.Method.invoke(Method.java:567)
   at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
   at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
   at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
   at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
   at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
   at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
   at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
   at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
   at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
   at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
   at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
   at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
   at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
   at org.junit.runner.JUnitCore.run(JUnitCore.java:160)
   at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)
   at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
   at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
   at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)

Process finished with exit code -1