完美解决failed to configure a datasource: ‘url‘ attribute is not specified and no em

浅浅的花香味﹌ 2023-09-28 22:04 12阅读 0赞

## 一. 异常现象failed to configure a datasource: 'url' attribute is not specified and no em ##

我在Spring Boot中关联MySQL、Mybatis进行数据库开发时，按照正常步骤添加了相关数据库的依赖，也进行了必要的数据库配置，结果在项目启动时出现如下异常信息：

***************************
    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).
    
    
    Process finished with exit code 1

看提示信息是说当前项目没有配置DataSource相关的配置！

## 二. failed to configure a datasource: ‘url‘ attribute is not specified and no em异常原因 ##

其实这个异常在SpringBoot中是一个比较常见的异常，一般是因为SpringBoot自动配置时，检测到我们添加了MySQL、Oracle、Mybatis等和数据库相关的依赖包，结果我们的配置文件中却没有添加数据库相关的配置，比如：

spring:
      datasource:
        driver-class-name: com.mysql.jdbc.Driver
        url: jdbc:mysql://localhost:3306/db?characterEncoding=utf-8
        username: root
        password: root

## 三. 解决办法failed to configure a datasource: 'url' attribute is not specified and no em ##

**针对以上原因造成的异常，可以采用如下办法解决：**

1.  在application.yml/application.properties中添加数据库相关配置；
2.  在SpringBootApplication注解中进行数据库配置的排除，即@SpringBootApplication(exclude= \{DataSourceAutoConfiguration.*class*\})。  
      
    以上两种解决办法，可以解决一般的情况，但是还有一种情况比较特殊，就是当我们进行Spring Boot分模块开发，且不同模块中有多个application.yml或application.properties配置文件时造成的，如下图所示：![cdb8b81787394cfcb10aaabb4485a8b1.png][]

我的这个案例中，我是把一个Spring Boot项目拆分成了shop-web、shop-service、shop-mapper等若干个模块，shop-mapper模块是数据库操作层，里面有个application.yml配置文件进行了数据库连接配置；shop-web模块中也有个application.yml文件，进行了端口、程序名等的配置。我把入口类写在shop-web模块中，然后进行项目启动，结果也产生了上面的异常信息。![7953718daf4840cfa9ee44b09b7de0c0.png][]

**造成该异常的原因，是因为我这个项目中是分模块开发，但是这几个模块共同组成了一个项目，shop-web模块依赖shop-service，shop-service模块依赖shop-mapper，这样就相当于一个项目中产生了2个application.yml文件，web层的application.yml文件把mapper层的application.yml配置给覆盖掉了，所以产生了以上异常。**  
  
**解决办法有2种思路：**

1.  **把shop-web模块中的application.yml文件改成application.properties；**
2.  **对不同模块中的配置文件，以application-\*.yml的形式命名,比如application-mapper.yml,application-service.yml等，然后在最顶层的shop-web模块配置文件中，通过spring.profiles.active进行激活配置，如下图所示：**![6289fed7d4e943e5a67e123a8fb3b4a7.png][]

\-------------------------------------------------

如果是别的项目导致failed to configure a datasource: 'url' attribute is not specified and no em，

原因：项目新搭建的时候，引入了[mybatis][]等框架，但是没有在yml等配置文件中配置链接，所以导致报错。

解决：1.删掉mybatis等[框架][Link 1]的引用，2.配置数据库再链接。

[cdb8b81787394cfcb10aaabb4485a8b1.png]: https://img-blog.csdnimg.cn/cdb8b81787394cfcb10aaabb4485a8b1.png
[7953718daf4840cfa9ee44b09b7de0c0.png]: https://img-blog.csdnimg.cn/7953718daf4840cfa9ee44b09b7de0c0.png
[6289fed7d4e943e5a67e123a8fb3b4a7.png]: https://img-blog.csdnimg.cn/6289fed7d4e943e5a67e123a8fb3b4a7.png
[mybatis]: https://so.csdn.net/so/search?q=mybatis&spm=1001.2101.3001.7020
[Link 1]: https://so.csdn.net/so/search?q=%E6%A1%86%E6%9E%B6&spm=1001.2101.3001.7020

完美解决failed to configure a datasource: ‘url‘ attribute is not specified and no em

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