面试时，好多公司问ibatis。于是，我就从mybatis开始学习这一套orm技术。自己练习着写了个小项目。遇到如下问题：

Exception in thread "main" org.apache.ibatis.exceptions.PersistenceException:
### Error building SqlSession.
### The error may exist in bean/User.xml
### Cause: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'User'.  Cause: java.lang.ClassNotFoundException: Cannot find class: User
 at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:23)
 at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:51)
 at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:35)
 at test.TestMybatis.main(TestMybatis.java:49)
Caused by: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'User'.  Cause: java.lang.ClassNotFoundException: Cannot find class: User
 at org.apache.ibatis.builder.xml.XMLConfigBuilder.parseConfiguration(XMLConfigBuilder.java:106)
 at org.apache.ibatis.builder.xml.XMLConfigBuilder.parse(XMLConfigBuilder.java:89)
 at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:49)
 ... 2 more
Caused by: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'User'.  Cause: java.lang.ClassNotFoundException: Cannot find class: User
 at org.apache.ibatis.builder.xml.XMLMapperBuilder.configurationElement(XMLMapperBuilder.java:117)
 at org.apache.ibatis.builder.xml.XMLMapperBuilder.parse(XMLMapperBuilder.java:89)
 at org.apache.ibatis.builder.xml.XMLConfigBuilder.mapperElement(XMLConfigBuilder.java:319)
 at org.apache.ibatis.builder.xml.XMLConfigBuilder.parseConfiguration(XMLConfigBuilder.java:104)
 ... 4 more
Caused by: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'User'.  Cause: java.lang.ClassNotFoundException: Cannot find class: User
 at org.apache.ibatis.builder.BaseBuilder.resolveClass(BaseBuilder.java:100)
 at org.apache.ibatis.builder.xml.XMLStatementBuilder.parseStatementNode(XMLStatementBuilder.java:69)
 at org.apache.ibatis.builder.xml.XMLMapperBuilder.buildStatementFromContext(XMLMapperBuilder.java:132)
 at org.apache.ibatis.builder.xml.XMLMapperBuilder.buildStatementFromContext(XMLMapperBuilder.java:125)
 at org.apache.ibatis.builder.xml.XMLMapperBuilder.configurationElement(XMLMapperBuilder.java:115)
 ... 7 more
Caused by: org.apache.ibatis.type.TypeException: Could not resolve type alias 'User'.  Cause: java.lang.ClassNotFoundException: Cannot find class: User
 at org.apache.ibatis.type.TypeAliasRegistry.resolveAlias(TypeAliasRegistry.java:114)
 at org.apache.ibatis.builder.BaseBuilder.resolveAlias(BaseBuilder.java:127)
 at org.apache.ibatis.builder.BaseBuilder.resolveClass(BaseBuilder.java:98)
 ... 11 more
Caused by: java.lang.ClassNotFoundException: Cannot find class: User
 at org.apache.ibatis.io.ClassLoaderWrapper.classForName(ClassLoaderWrapper.java:188)
 at org.apache.ibatis.io.ClassLoaderWrapper.classForName(ClassLoaderWrapper.java:87)
 at org.apache.ibatis.io.Resources.classForName(Resources.java:254)
 at org.apache.ibatis.type.TypeAliasRegistry.resolveAlias(TypeAliasRegistry.java:110)
 ... 13 more
一看控制台，吓我一跳，这什么玩意儿……。

解决办法：mapper配置文件的resulttype需要和mybatis配置文件中alias对应。如下：

http://s14/mw690/002KiXxjzy6Ib259Mdf7d&690遇到问题：Error parsing SQL Mapper Configuration" TITLE="mybatis 遇到问题：Error parsing SQL Mapper Configuration" />

http://s9/mw690/002KiXxjzy6Ib25zPjW58&690遇到问题：Error parsing SQL Mapper Configuration" TITLE="mybatis 遇到问题：Error parsing SQL Mapper Configuration" />