mybatis****Caused by: java.lang.IllegalArgumentException: Result Maps collection already contains va

org.apache.ibatis.exceptions.PersistenceException: 
### Error building SqlSession.
### The error may exist in com/cx/dao/ProductMapper.xml
### The error occurred while processing mapper_resultMap[BaseResultMap]
### 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 'com/cx/dao/ProductMapper.xml'. Cause: java.lang.IllegalArgumentException: Result Maps collection already contains value for com.cx.dao.ProductMapper.BaseResultMap

	at 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 MyTest2.before(MyTest2.java:23)
	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.RunBefores.evaluate(RunBefores.java:24)
	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.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'com/cx/dao/ProductMapper.xml'. Cause: java.lang.IllegalArgumentException: Result Maps collection already contains value for com.cx.dao.ProductMapper.BaseResultMap
	at org.apache.ibatis.builder.xml.XMLConfigBuilder.parseConfiguration(XMLConfigBuilder.java:121)
	at org.apache.ibatis.builder.xml.XMLConfigBuilder.parse(XMLConfigBuilder.java:98)
	at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:78)
	... 24 more
Caused by: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'com/cx/dao/ProductMapper.xml'. Cause: java.lang.IllegalArgumentException: Result Maps collection already contains value for com.cx.dao.ProductMapper.BaseResultMap
	at org.apache.ibatis.builder.xml.XMLMapperBuilder.configurationElement(XMLMapperBuilder.java:122)
	at org.apache.ibatis.builder.xml.XMLMapperBuilder.parse(XMLMapperBuilder.java:94)
	at org.apache.ibatis.builder.annotation.MapperAnnotationBuilder.loadXmlResource(MapperAnnotationBuilder.java:182)
	at org.apache.ibatis.builder.annotation.MapperAnnotationBuilder.parse(MapperAnnotationBuilder.java:129)
	at org.apache.ibatis.binding.MapperRegistry.addMapper(MapperRegistry.java:72)
	at org.apache.ibatis.binding.MapperRegistry.addMappers(MapperRegistry.java:97)
	at org.apache.ibatis.binding.MapperRegistry.addMappers(MapperRegistry.java:105)
	at org.apache.ibatis.session.Configuration.addMappers(Configuration.java:771)
	at org.apache.ibatis.builder.xml.XMLConfigBuilder.mapperElement(XMLConfigBuilder.java:365)
	at org.apache.ibatis.builder.xml.XMLConfigBuilder.parseConfiguration(XMLConfigBuilder.java:119)
	... 26 more
Caused by: java.lang.IllegalArgumentException: Result Maps collection already contains value for com.cx.dao.ProductMapper.BaseResultMap
	at org.apache.ibatis.session.Configuration$StrictMap.put(Configuration.java:947)
	at org.apache.ibatis.session.Configuration$StrictMap.put(Configuration.java:903)
	at org.apache.ibatis.session.Configuration.addResultMap(Configuration.java:660)
	at org.apache.ibatis.builder.MapperBuilderAssistant.addResultMap(MapperBuilderAssistant.java:209)
	at org.apache.ibatis.builder.ResultMapResolver.resolve(ResultMapResolver.java:47)
	at org.apache.ibatis.builder.xml.XMLMapperBuilder.resultMapElement(XMLMapperBuilder.java:289)
	at org.apache.ibatis.builder.xml.XMLMapperBuilder.resultMapElement(XMLMapperBuilder.java:253)
	at org.apache.ibatis.builder.xml.XMLMapperBuilder.resultMapElements(XMLMapperBuilder.java:245)
	at org.apache.ibatis.builder.xml.XMLMapperBuilder.configurationElement(XMLMapperBuilder.java:118)
	... 35 more

该异常大致为：Caused by: java.lang.IllegalArgumentException: Result Maps collection already contains value for com.cx.dao.ProductMapper.BaseResultMap
原因：使用mybatis****多次生成mapper时，未将之前生成的mapper.xml删除，导致其在原有的xml里追加内容。最终导致BaseResultMap重复。
解决方法：不要忘记删除已生成的mapper.xml，重新生成。
解决方法：不要忘记删除已生成的mapper.xml，重新生成。
解决方法：不要忘记删除已生成的mapper.xml，重新生成。