在学完spring后（“春”，当然这不是真的春啊），会发现好多东西都不用亲手去写了，在框架之中开发的确是省了不少事，当然代码方面省事了，配置文件就需要稍微费点事，相比之下呢，我更喜欢后者。
说到这里呢，就不得不提一下当下SSM主流框架（spring,spring-mvc,mybatis），当然，这个大家都知道，所以就不再赘述。今天说一下常遇到的一个问题：Error building SqlSession.（创建会话出错）
闲话不多说，大家看一下事故现场，下面的场面太大了，怕你没耐心看，所以在这里说明问题出在哪里，很容易我们可以看到Error building SqlSession.字样，那么为什么会出现这样的情况呢？
### Error building SqlSession.
### The error may exist in config/mapper/stuMapper.xml
### Cause: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause:……
我们接着看下一行，The error may exist in config/mapper/stuMapper.xml，这就说明我们的映射文件出错了，而且这种错误八成是配置的包名+类名+类出现了问题。以我的工程为例，大家请看，是不是发现了，改过来之后就可以正常运行了。
出错代码如下图：
正确代码如下图：
这个时候再运行程序就ok了。
下面附上事故现场：
org.apache.ibatis.exceptions.PersistenceException:
### Error building SqlSession.
### The error may exist in config/mapper/stuMapper.xml
### 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 'config/mapper/stuMapper.xml'. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'com.zzxtit.boot.mybatis.hello.Student'. Cause: java.lang.ClassNotFoundException: Cannot find class: com.zzxtit.boot.mybatis.hello.Student
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 com.zzxtit.boot.mybatis.first.FirstMain.init(FirstMain.java:24)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
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.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:538)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:760)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:460)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:206)
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 'config/mapper/stuMapper.xml'. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'com.zzxtit.boot.mybatis.hello.Student'. Cause: java.lang.ClassNotFoundException: Cannot find class: com.zzxtit.boot.mybatis.hello.Student
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)
... 25 more
Caused by: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'config/mapper/stuMapper.xml'. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'com.zzxtit.boot.mybatis.hello.Student'. Cause: java.lang.ClassNotFoundException: Cannot find class: com.zzxtit.boot.mybatis.hello.Student
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.xml.XMLConfigBuilder.mapperElement(XMLConfigBuilder.java:373)
at org.apache.ibatis.builder.xml.XMLConfigBuilder.parseConfiguration(XMLConfigBuilder.java:119)
... 27 more
Caused by: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'com.zzxtit.boot.mybatis.hello.Student'. Cause: java.lang.ClassNotFoundException: Cannot find class: com.zzxtit.boot.mybatis.hello.Student
at org.apache.ibatis.builder.BaseBuilder.resolveClass(BaseBuilder.java:118)
at org.apache.ibatis.builder.xml.XMLStatementBuilder.parseStatementNode(XMLStatementBuilder.java:74)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.buildStatementFromContext(XMLMapperBuilder.java:137)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.buildStatementFromContext(XMLMapperBuilder.java:130)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.configurationElement(XMLMapperBuilder.java:120)
... 30 more
Caused by: org.apache.ibatis.type.TypeException: Could not resolve type alias 'com.zzxtit.boot.mybatis.hello.Student'. Cause: java.lang.ClassNotFoundException: Cannot find class: com.zzxtit.boot.mybatis.hello.Student
at 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)
... 34 more
Caused by: java.lang.ClassNotFoundException: Cannot find class: com.zzxtit.boot.mybatis.hello.Student
at org.apache.ibatis.io.ClassLoaderWrapper.classForName(ClassLoaderWrapper.java:200)
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)
... 36 more