idea 启动官网spring boot demo 报错

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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).

-- ::02.649  WARN  --- [           main] o.s.boot.SpringApplication               : Unable to close ApplicationContext

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration': Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.transaction.annotation.ProxyTransactionManagementConfiguration': Initialization of bean failed; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'org.springframework.context.annotation.ConfigurationClassPostProcessor.importRegistry' available
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$(AbstractBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$(AbstractBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.context.event.AbstractApplicationEventMulticaster.retrieveApplicationListeners(AbstractApplicationEventMulticaster.java:) ~[spring-context-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.context.event.AbstractApplicationEventMulticaster.getApplicationListeners(AbstractApplicationEventMulticaster.java:) ~[spring-context-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:) ~[spring-context-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:) ~[spring-context-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:) ~[spring-context-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.boot.availability.AvailabilityChangeEvent.publish(AvailabilityChangeEvent.java:) ~[spring-boot-2.3..RELEASE.jar:2.3..RELEASE]
    at org.springframework.boot.availability.AvailabilityChangeEvent.publish(AvailabilityChangeEvent.java:) ~[spring-boot-2.3..RELEASE.jar:2.3..RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.doClose(ServletWebServerApplicationContext.java:) ~[spring-boot-2.3..RELEASE.jar:2.3..RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.close(AbstractApplicationContext.java:) ~[spring-context-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.boot.SpringApplication.handleRunFailure(SpringApplication.java:) [spring-boot-2.3..RELEASE.jar:2.3..RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:) [spring-boot-2.3..RELEASE.jar:2.3..RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:) [spring-boot-2.3..RELEASE.jar:2.3..RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:) [spring-boot-2.3..RELEASE.jar:2.3..RELEASE]
    at com.example.demo.DemoApplication.main(DemoApplication.java:) [classes/:na]
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.transaction.annotation.ProxyTransactionManagementConfiguration': Initialization of bean failed; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'org.springframework.context.annotation.ConfigurationClassPostProcessor.importRegistry' available
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$(AbstractBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$(AbstractBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.aop.framework.autoproxy.BeanFactoryAdvisorRetrievalHelper.findAdvisorBeans(BeanFactoryAdvisorRetrievalHelper.java:) ~[spring-aop-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator.findCandidateAdvisors(AbstractAdvisorAutoProxyCreator.java:) ~[spring-aop-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator.findEligibleAdvisors(AbstractAdvisorAutoProxyCreator.java:) ~[spring-aop-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator.getAdvicesAndAdvisorsForBean(AbstractAdvisorAutoProxyCreator.java:) ~[spring-aop-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.wrapIfNecessary(AbstractAutoProxyCreator.java:) ~[spring-aop-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.postProcessAfterInitialization(AbstractAutoProxyCreator.java:) ~[spring-aop-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    ...  common frames omitted
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'org.springframework.context.annotation.ConfigurationClassPostProcessor.importRegistry' available
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanDefinition(DefaultListableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getMergedLocalBeanDefinition(AbstractBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.context.annotation.ConfigurationClassPostProcessor$ImportAwareBeanPostProcessor.postProcessBeforeInitialization(ConfigurationClassPostProcessor.java:) ~[spring-context-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:) ~[spring-beans-5.2..RELEASE.jar:5.2..RELEASE]
    ...  common frames omitted

Process finished with exit code 

【原因】

没有配置数据库连接字符串导致

【解决】

程序入口处添加【exclude = {DataSourceAutoConfiguration.class }】如下所示，然后再运行就可以了。

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class })
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

}

（完）