参考网上的博客  敲spring boot 发现一个问题，困扰了半天，在这里记录下：

@SpringBootApplication(exclude = DataSourceAutoConfiguration.class) 的 作用是  ：取消数据库配置。

所以在用到数据库的时候记得将他改为 @SpringBootApplication ， 否则会报错：如下
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘xxController‘: Unsatisfied dependency expressed through field ‘xxMapper‘; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘xxMapper‘ defined in file [D:\workspacesidea\pear\target\classes\com\wqq\mapper\xxMapper.class]: Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Property ‘sqlSessionFactory‘ or ‘sqlSessionTemplate‘ are required

@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)