使用idea创建Spring Boot项目时，在选择组件时添加了mysql、mybatis，然后在第一次启动的时候启动报错，错误信息如下：
APPLICATION FAILED TO START
Description: Failed to auto-configure a DataSource: 'spring.datasource.url' is not specified and no embedded datasource could be auto-configured. Reason: Failed to determine a suitable driver class Action: Consider the following: If you want an embedded database (H2, HSQL or Derby), please put it on the classpath.
If you have database settings to be loaded from a particular profile you may need to activate it (no profiles are currently active).
在多方查证后，需要在启动类的@EnableAutoConfiguration或@SpringBootApplication中添加exclude
= {DataSourceAutoConfiguration.class}，排除此类的autoconfig。启动以后就可以正常运行。
这是因为添加了数据库组件，所以autoconfig会去读取数据源配置，而我新建的项目还没有配置数据源，所以会导致异常出现。
即：@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
