本博文源于笔者自身学习的mybatis，在学习一对多的过程中，出现了一个错误。这个错误是org.apache.ibatis.exceptions.PersistenceException:
Error building SqlSession.
The error may exist in mappers/EmpMapper.xml
The error occurred while processing mapper_resultMap[empAndDeptResultMapTwo]_association[dept]
Cause: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is ‘mappers/EmpMapper.xml’. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias ‘Dept’. Cause: java.lang.ClassNotFoundException: Cannot find class: Dept
问题来由
在建立一对多映射关系中，想要遍历查询一对多关系，发现报了这样一大堆错误。
"C:\Program Files\Java\jdk1.8.0_192\bin\java.exe" -ea -Didea.test.cyclic.buffer.size=1048576 "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.2\lib\idea_rt.jar=12996:C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.2\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.2\lib\idea_rt.jar;C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.2\plugins\junit\lib\junit5-rt.jar;C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.2\plugins\junit\lib\junit-rt.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_192\jre\lib\rt.jar;C:\Users\Administrator\IdeaProjects\mybatis2\MyBatis_demo3\target\test-classes;C:\Users\Administrator\IdeaProjects\mybatis2\MyBatis_demo3\target\classes;C:\Users\Administrator\.m2\repository\org\mybatis\mybatis\3.5.7\mybatis-3.5.7.jar;C:\Users\Administrator\.m2\repository\junit\junit\4.12\junit-4.12.jar;C:\Users\Administrator\.m2\repository\org\hamcrest\hamcrest-core\1.3\hamcrest-core-1.3.jar;C:\Users\Administrator\.m2\repository\mysql\mysql-connector-java\5.1.3\mysql-connector-java-5.1.3.jar;C:\Users\Administrator\.m2\repository\log4j\log4j\1.2.17\log4j-1.2.17.jar" com.intellij.rt.junit.JUnitStarter -ideVersion5 -junit4 ResultMapTest,testgetEmpAndDeptorg.apache.ibatis.exceptions.PersistenceException: ### Error building SqlSession.### The error may exist in mappers/EmpMapper.xml### The error occurred while processing mapper_resultMap[empAndDeptResultMapTwo]_association[dept]### Cause: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'mappers/EmpMapper.xml'. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'Dept'. Cause: java.lang.ClassNotFoundException: Cannot find class: Deptat org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:80)at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:64)at com.atguigu.mybatis.utils.SqlSessionUtils.getSqlSession(SqlSessionUtils.java:17)at ResultMapTest.testgetEmpAndDept(ResultMapTest.java:31)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$2.evaluate(ParentRunner.java:268)at org.junit.runners.ParentRunner.run(ParentRunner.java:363)at org.junit.runner.JUnitCore.run(JUnitCore.java:137)at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)Caused by: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'mappers/EmpMapper.xml'. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'Dept'. Cause: java.lang.ClassNotFoundException: Cannot find class: Deptat org.apache.ibatis.builder.xml.XMLConfigBuilder.parseConfiguration(XMLConfigBuilder.java:122)at org.apache.ibatis.builder.xml.XMLConfigBuilder.parse(XMLConfigBuilder.java:99)at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:78)... 25 moreCaused by: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'mappers/EmpMapper.xml'. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'Dept'. Cause: java.lang.ClassNotFoundException: Cannot find class: Deptat org.apache.ibatis.builder.xml.XMLMapperBuilder.configurationElement(XMLMapperBuilder.java:123)at org.apache.ibatis.builder.xml.XMLMapperBuilder.parse(XMLMapperBuilder.java:95)at org.apache.ibatis.builder.xml.XMLConfigBuilder.mapperElement(XMLConfigBuilder.java:378)at org.apache.ibatis.builder.xml.XMLConfigBuilder.parseConfiguration(XMLConfigBuilder.java:120)... 27 moreCaused by: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'Dept'. Cause: java.lang.ClassNotFoundException: Cannot find class: Deptat org.apache.ibatis.builder.BaseBuilder.resolveClass(BaseBuilder.java:118)at org.apache.ibatis.builder.xml.XMLMapperBuilder.resultMapElement(XMLMapperBuilder.java:263)at org.apache.ibatis.builder.xml.XMLMapperBuilder.processNestedResultMappings(XMLMapperBuilder.java:400)at org.apache.ibatis.builder.xml.XMLMapperBuilder.lambda$buildResultMappingFromContext$0(XMLMapperBuilder.java:383)at org.apache.ibatis.parsing.XNode.getStringAttribute(XNode.java:200)at org.apache.ibatis.builder.xml.XMLMapperBuilder.buildResultMappingFromContext(XMLMapperBuilder.java:382)at org.apache.ibatis.builder.xml.XMLMapperBuilder.resultMapElement(XMLMapperBuilder.java:280)at org.apache.ibatis.builder.xml.XMLMapperBuilder.resultMapElement(XMLMapperBuilder.java:254)at org.apache.ibatis.builder.xml.XMLMapperBuilder.resultMapElements(XMLMapperBuilder.java:246)at org.apache.ibatis.builder.xml.XMLMapperBuilder.configurationElement(XMLMapperBuilder.java:119)... 30 moreCaused by: org.apache.ibatis.type.TypeException: Could not resolve type alias 'Dept'. Cause: java.lang.ClassNotFoundException: Cannot find class: Deptat org.apache.ibatis.type.TypeAliasRegistry.resolveAlias(TypeAliasRegistry.java:120)at org.apache.ibatis.builder.BaseBuilder.resolveAlias(BaseBuilder.java:149)at org.apache.ibatis.builder.BaseBuilder.resolveClass(BaseBuilder.java:116)... 39 moreCaused by: java.lang.ClassNotFoundException: Cannot find class: Deptat org.apache.ibatis.io.ClassLoaderWrapper.classForName(ClassLoaderWrapper.java:196)at org.apache.ibatis.io.ClassLoaderWrapper.classForName(ClassLoaderWrapper.java:89)at org.apache.ibatis.io.Resources.classForName(Resources.java:261)at org.apache.ibatis.type.TypeAliasRegistry.resolveAlias(TypeAliasRegistry.java:116)... 41 moreProcess finished with exit code -1解决方案
将mapper.xml中的javaType改成全称就行了。包含报名加类名。
来源地址：https://blog.csdn.net/m0_37149062/article/details/129321019
