Error creating bean with name

最近在学一个东西，要使用SSM新建一个案例，是这样滴，我有如下

1. DeptDAO
2. DeptService
3. DeptServiceImpl
4. DeptController
5. Dept
6. Mybatis

首先，我不是太清楚有了DAO还要有Service，不过这个不是本文章的重点。

重点是，报如下错，两个不同的错误吧

错误1：

2019-04-02 22:09:08.697 ERROR 12080 --- [nio-8001-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.vae.springcloud.dao.DeptDAO.findAll] with root cause

org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.vae.springcloud.dao.DeptDAO.findAll

错误2：

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'deptController': Unsatisfied dependency expressed through field 'deptService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'deptServiceImpl': Unsatisfied dependency expressed through field 'deptDAO'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'deptDAO' defined in file [D:Java CodeSpringCloudprovider argetclassescomvaespringclouddaoDeptDAO.class]: Unsatisfied dependency expressed through bean property 'sqlSessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSessionFactory' defined in class path resource [org/mybatis/spring/boot/autoconfigure/MybatisAutoConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.apache.ibatis.session.SqlSessionFactory]: Factory method 'sqlSessionFactory' threw exception; nested exception is org.springframework.core.NestedIOException: Failed to parse mapping resource: 'file [D:Java CodeSpringCloudprovider argetclassesmybatismapperDeptMapper.xml]'; nested exception is org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'file [D:Java CodeSpringCloudprovider argetclassesmybatismapperDeptMapper.xml]'. Cause: java.lang.IllegalArgumentException: Mapped Statements collection already contains value for com.vae.springcloud.dao.DeptDAO.findAll. please check mybatis/mapper/DeptMapper.xml and file [D:Java CodeSpringCloudprovider argetclassesmybatismapperDeptMapper.xml]

很奇怪的错误，我看错误说没有bean，我在网上搜啊搜，网上的文章要么是抄袭的，要么是复制粘贴的，要么解释的答案简单的很，根本没有上升到我这个层次。我纠结了好几天，最终发现，错误居然是！！！居然是Mybatis的配置文件！！

我自己写的mybatis文章里面，说道，mybatis加载mapper.xml需要这样

<!-- 加载映射文件-->
    <mappers>
        <mapper resource="config/Message.xml"/>
    </mappers>

这样是可行，但是，这就是造成我错误的原因。这种方式，我当时使用的是SqlSession来主动加载Mybatis文件的，现在我想自动的去映射，就不能这么写了，需要在yml配置文件里面写

mybatis:
  config-location: classpath:mybatis/mybatis.cfg.xml        # mybatis配置文件所在路径
  type-aliases-package: com.atguigu.springcloud.entities    # 所有Entity别名类所在包
  mapper-locations: classpath:mybatis/mapper/**/*.xml        # mapper映射文件

总之，这次的错误，完全是因为我不熟悉Mybatis造成的，为此困惑了好多天。

顺便一提，我正在学习的这个项目是SpringCloud，学会之后，我会专门去详细的讲SpringCloud。到时再提一提这个因为我的无知而造成的报错。