spring boot启动报错Error starting ApplicationContext（未能配置数据源）

主要错误：Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured.

未能配置数据源:未指定“url”属性，也无法配置嵌入式数据源。

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2019-06-03 09:47:45.300 ERROR 23160 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 

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APPLICATION FAILED TO START
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Description:

Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be 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).

原因：

spring boot默认会加载org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration类，DataSourceAutoConfiguration类使用了@Configuration注解向spring注入了dataSource bean。因为工程中没有关于dataSource相关的配置信息，当spring创建dataSource bean因缺少相关的信息就会报错。

两种解决办法

1.在Application类上加

@EnableAutoConfiguration(exclude={DataSourceAutoConfiguration.class})

2.配置数据源：

例如在application配置文件中：

spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://ip:端口号/数据库名称?useSSL=false&useUnicode=true&characterEncoding=utf8&serverTimezone=GMT%2B8