项目场景：

SSM基本框架测试，实现helloworld报错如下:
'sqlSessionFactory’开头的东西，后面才是重点。

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSessionFactory' defined in class path resource [application-dao.xml]: 
Invocation of init method failed; nested exception is 
org.springframework.core.NestedIOException: 
Failed to parse config resource: class path resource [mybatis.cfg.xml];

解决方案：

1. 配置文件内容是否出错，复制过来的没有内容上的错误。
2. 项目结构是否搭建完成即Controller层，Service层，Mapper层，相关注释有没有写上。

项目结构：

LoginController:这里的restcontroller注释

@RestController
public class LoginController {
    /**
     * 跳转到登录页面
     * @return
     */
    @RequestMapping("/goLoginPage")
    public String goLogin(){
        return "login";
    }
}

impl.StudentService:这里的service注释

@Service
public class StudentService implements service.StudentService {

    @Autowired
    private StudentDao studentDao;

    @Override
    public Student getStudentById(long studentId) {
        return studentDao.getStudentById(studentId);
    }
}

StudentMapper:这里的mapper注释

@Mapper
public interface DeptMapper extends BaseMapper<Dept> {

    int mydeleteById(int id);
}

如果不在这里写mapper和sevice，那就在启动文件那里写mapperscan和componentscan，不写的话@Autowired标签会报错。

@SpringBootApplication
@MapperScan("generator.mapper")
@ComponentScan("generator.service")
public class MybatisplusfinalApplication {

    public static void main(String[] args) {
        SpringApplication.run(MybatisplusfinalApplication.class, args);
    }

}

另外如果出现Can not find table primary key in Class的错误是没在实体类那里加@TabliId标签，强烈建议用MybatisX插件去搞，最标准。只要补一下Mapper标签就可以了。

Invalid bound statement (not found): mapper.StudentMapper.selectById

3. 如果上面没问题，报错原因是因为在mybatis里面这段代码没有删除导致spring和mybatis都扫描了一遍xml，就出错了。删掉Mybatis.cfg.xml里的扫描。

//Mybatis.cfg.xml
<!-- 4.加载Dao层映射文件 --
    <mappers>
        <mapper resource="mappers/StudentMapper.xml"></mapper>
    </mappers>


//application-dao.xml
<!-- 3,配置aop -->
    <aop:config>
        <!-- 声明一个切入点 -->
        <aop:pointcut expression="execution(* service.impl.*.*(..))"
                      id="pc1" />
        <aop:advisor advice-ref="txAdvise" pointcut-ref="pc1" />
    </aop:config>

附上完整application-dao.xml代码

<?xml version="1.0" encoding="UTF-8"?>
<!-- 头文件 -->
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/tx
      http://www.springframework.org/schema/tx/spring-tx.xsd
        ">
    <!-- 1.加载属性集文件 -->
    <context:property-placeholder location="classpath:jdbc.properties"/>

    <!-- 2.建数据源 -->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="${mysql.driver}"></property>
        <property name="url" value="${mysql.url}"></property>
        <property name="username" value="${mysql.username}"></property>
        <property name="password" value="${mysql.password}"></property>
    </bean>
    <!-- 3.配置SqlSessionFactory -->
    <bean id="sqlSessionFactory" name="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- 注入dataSource -->
        <property name="dataSource" ref="dataSource"></property>
        <!-- 加载 mybtais.cfg.xml -->
        <property name="configLocation" value="classpath:mybatis.cfg.xml"></property>
    </bean>
    <!-- dao接口所在包名，Spring会自动查找之中的类 根据dao接口  -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!-- 提供dao接口所在以包 如果有多个包，可以使用,去隔开-->
        <property name="basePackage" value="dao"></property>
        <!-- 注入sessionFactory -->
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"></property>
    </bean>
    <!-- 配置声明式事物 -->
    <!-- 1.声明事务管理器 -->
    <bean id="transactionManager"
          class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"></property>
    </bean>

    <!-- 2.声明事务事务传播特性 【哪些方法加事务。哪此不加】 -->
    <tx:advice id="txAdvise" transaction-manager="transactionManager">
        <tx:attributes>
            <!-- 在切面里面如查有方法名是add开头的就加事物 -->
            <tx:method name="add*" propagation="REQUIRED" />
            <tx:method name="save*" propagation="REQUIRED" />
            <tx:method name="delete*" propagation="REQUIRED" />
            <tx:method name="del*" propagation="REQUIRED" />
            <tx:method name="update*" propagation="REQUIRED" />
            <tx:method name="load*" propagation="REQUIRED" />
            <tx:method name="get*" read-only="true" />
            <tx:method name="find*" read-only="true" />
            <tx:method name="*" read-only="true" />
        </tx:attributes>
    </tx:advice>
    <!-- 3,配置aop -->
    <aop:config>
        <!-- 声明一个切入点 -->
        <aop:pointcut expression="execution(* service.impl.*.*(..))"
                      id="pc1" />
        <aop:advisor advice-ref="txAdvise" pointcut-ref="pc1" />
    </aop:config>
</beans>