有人说想看：org.springframework.beans.factory.UnsatisfiedDependencyException 异常解决方案，那么今天，他来了！！！！

刚开始搞SpringBoot的你，意气风发，心猿意马，抱着抛弃传统MVC繁琐配置的伟大目标，热切的去拥抱SpringBoot的框架模式，因为你知道springboot 的核心：约定大于配置！所以你创建了工程，实体类，mapper,service，impl,还有启动类一番操作猛如虎，点击启动按钮后，哦买噶，各种报错让人仙仙欲死、、、、、

比如这样的

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'deptsController': Unsatisfied dependency expressed through field 'deptService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'deptServiceImpl': Unsatisfied dependency expressed through field 'deptDao'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'deptDao' defined in file [E:\Project\springcloud\springcloud-provider-dept-8001\target\classes\com\springcloud\mapper\DeptDao.class]: Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Property 'sqlSessionFactory' or 'sqlSessionTemplate' are required
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:596) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:374) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1411) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:592) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:845) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:877) ~[spring-context-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.1.7.RELEASE.jar:2.1.7.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:743) [spring-boot-2.1.7.RELEASE.jar:2.1.7.RELEASE]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:390) [spring-boot-2.1.7.RELEASE.jar:2.1.7.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:312) [spring-boot-2.1.7.RELEASE.jar:2.1.7.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1214) [spring-boot-2.1.7.RELEASE.jar:2.1.7.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1203) [spring-boot-2.1.7.RELEASE.jar:2.1.7.RELEASE]
	at com.springcloud.Dept_Provider_8001_Application.main(Dept_Provider_8001_Application.java:18) [classes/:na]
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'deptServiceImpl': Unsatisfied dependency expressed through field 'deptDao'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'deptDao' defined in file [E:\Project\springcloud\springcloud-provider-dept-8001\target\classes\com\springcloud\mapper\DeptDao.class]: Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Property 'sqlSessionFactory' or 'sqlSessionTemplate' are required
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:596) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:374) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1411) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:592) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:277) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1251) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1171) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:593) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	... 19 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'deptDao' defined in file [E:\Project\springcloud\springcloud-provider-dept-8001\target\classes\com\springcloud\mapper\DeptDao.class]: Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Property 'sqlSessionFactory' or 'sqlSessionTemplate' are required
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1778) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:593) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:277) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1251) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1171) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:593) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	... 32 common frames omitted
Caused by: java.lang.IllegalArgumentException: Property 'sqlSessionFactory' or 'sqlSessionTemplate' are required
	at org.springframework.util.Assert.notNull(Assert.java:198) ~[spring-core-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.mybatis.spring.support.SqlSessionDaoSupport.checkDaoConfig(SqlSessionDaoSupport.java:74) ~[mybatis-spring-1.3.2.jar:1.3.2]
	at org.mybatis.spring.mapper.MapperFactoryBean.checkDaoConfig(MapperFactoryBean.java:73) ~[mybatis-spring-1.3.2.jar:1.3.2]
	at org.springframework.dao.support.DaoSupport.afterPropertiesSet(DaoSupport.java:44) ~[spring-tx-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1837) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1774) ~[spring-beans-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	... 42 common frames omitted

你撇了撇嘴，充满智慧的大脑开始转动，私心想着： 1.可能是实现类没有加@Servcie注解，你加上后，点击启动，报错依然顽固存在。心碎x1 2.可能是启动类上面没有加@MapperScan("com.xxx.mapper")，你加上后，点击启动，报错依然顽固存在。心碎x2 3.可能是ServiceImpl中的dao包没有导入 @Autowired，你加上后，点击启动，报错依然顽固存在。心碎 x3 怎么样是不是欲仙欲死，其乐无穷啊？

终上所述你已经列举了3种可能，但是你还差一条注解： @EnableAutoConfiguration

@EnableAutoConfiguration的主要作用是：启用Spring应用程序上下文的自动配置，尝试猜测和配置您可能需要的bean。自动配置类通常基于类路径和定义的bean应用。例如，如果你有 tomcat-embedded.jar在您的类路径中,你可能会想要一个TomcatEmbeddedServletContainerFactory(除非你定义自己的EmbeddedServletContainerFactory bean)。当使用SpringBootApplication时，上下文的自动配置将自动启用并添加此注释，因此不会产生额外的效果。自动配置尝试尽可能地智能化，并且在您定义更多自己的配置时将会备份。您总是可以手工排除()任何您不想应用的配置(如果您无法访问它们的话)。您也可以通过spring. autoconfigure将它们排除。排除属性。在用户定义的bean被注册之后，自动配置总是被应用。用@ enableautoconfiguration注释的类的包，通常通过@ springbootapplication，具有特殊的意义，经常被用作“默认”。例如，它将用于扫描@ entity类。通常建议在根包中放置@ enableautoconfiguration(如果您不使用@ springbootapplication)，以便可以搜索所有子包和类。自动配置类是常规的Spring配置bean。它们使用SpringFactoriesLoader机制(对该类进行键控)定位。通常，自动配置bean都是“有条件bean”(通常使用@ conditionalonclass和@ conditionalonmissingbean注释)。

上面一大堆关于@EnableAutoConfiguration注解解释是博主从别处拷贝而来，如果理解起来有点困难，你只需要知道他是Bean的自动装配工具，也许你会问，我为什么要这样做，我项目里面直接用@Import不行吗？当然可以，既然是自动配置，那当然是希望项目启动就加载。

好了观众朋友们，这一期的《母猪的产后护理》讲座已经结束了，感谢大家观看聆听，我们下期再见！

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