springboot 2.0 启动报错 Failed to auto-configure a DataSource
原因
在pom中添加了mybatis，mysql依赖后，如果application.properties中没有配置数据库连接方面的配置，则会报错：
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。
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APPLICATION FAILED TO START
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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).
解决方法
1.在启动类中加注解
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。