听说最近这个错误比较多，我专门做了几个小案例来测试，最后的测试结果来看 使用逆向工程的代码不会出现这个错误，只有自己手打的代码才会出现。然后大家先看下错误代码
错误代码：
严重: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'deptServiceImpl': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.baidu.mapper.DeptMapper com.baidu.dept.service.impl.DeptServiceImpl.DeptMapper; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.baidu.mapper.DeptMapper] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
Related cause: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'deptMapper' defined in URL [jar:file:/F:/maven/repository/com/baidu/baidu-dept-dao/0.0.1-SNAPSHOT/baidu-dept-dao-0.0.1-SNAPSHOT.jar!/com/baidu/mapper/DeptMapper.class]: Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: 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 'dept'. Cause: java.lang.ClassNotFoundException: Cannot find class: dept
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1214)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:543)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:772)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:839)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:538)
at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:446)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:328)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4939)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5434)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.ClassNotFoundException: Cannot find class: dept
at org.apache.ibatis.io.ClassLoaderWrapper.classForName(ClassLoaderWrapper.java:190)
at org.apache.ibatis.io.ClassLoaderWrapper.classForName(ClassLoaderWrapper.java:89)
at org.apache.ibatis.io.Resources.classForName(Resources.java:256)
at org.apache.ibatis.type.TypeAliasRegistry.resolveAlias(TypeAliasRegistry.java:113)
... 54 more
错误代码图片：（关键错误）
这里的错误原因说是没有实体类，经过我仔细排查发现了 在我们配置maven的时候少了个配置别名配置才导致的错误，接下来我给大家进行截图示范
截图：
运行成功界面：
