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   : 
 
***************************
APPLICATION FAILED TO START
***************************
 
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).

由第一幅图知，最先发生错误的地方在创建datasource这个Bean，之后造成dao,service,controller都报错了

我使用application.properties配置文件时出现此错误（换成application.yml时没有出现此错误）

原因：

com.mysql.jdbc.Driver的版本太低，与springboot不兼容（springboot使用的2.3.2.RELEASE）

  <!-- mysql驱动 -->
       <!-- 此版本太低--> 
       <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.18</version>
        </dependency>

更换以下依赖后正常了

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.21</version>
        </dependency>

总结：使用application.properties配置文件时springboot的2.3.2.RELEASE与mysql-connector-java的5.1.18不兼容

其他可能的原因，又看到这篇写的比较多，评论也多

查看：

https://blog.csdn.net/qq_40223688/article/details/88191732