创作背景：

本人在学习springboot时遇到一个错误困扰了我很长时间，今天也是终于解决啦！

下面记录一下学习的过程~（解决方案可以直接在最下面查看）

一.首先使用spring框架测试是否能够自动连接本地数据库：

1.在配置文件中添加本地数据库信息（如用户名密码等）

2.添加测试类监测是否连接成功：

3.运行结果：

（红色只是警告可以忽略）此时还一切正常，没有任何问题。

二.测试根据id信息查找数据库中的数据

1.首先在pojo层创建student.java 与数据库中的信息相对应

2.然后在dao层创建StudentDao.java编写查找语句的代码

3.最后就可以测试啦！在测试类中进行测试：

三.出现错误提示找不到dao.StudentDao

注意看此时是没有任何语法错误的，可问题是怎么运行都不成功，总提示我找不到dao.StudentDao，我也是尝试了各种方法

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'com.myspring.childdemo.ChildDemoApplicationTests': Unsatisfied dependency expressed through field 'studentDao': No qualifying bean of type 'dao.StudentDao' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:788)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:768)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:145)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:509)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1439)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireBeanProperties(AbstractAutowireCapableBeanFactory.java:398)
    at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:143)
    at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:98)
    at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:260)
    at org.springframework.test.context.junit.jupiter.SpringExtension.postProcessTestInstance(SpringExtension.java:163)
    at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
    at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179)
    at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625)
    at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
    at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
    at java.base/java.util.stream.StreamSpliterators$WrappingSpliterator.forEachRemaining(StreamSpliterators.java:310)
    at java.base/java.util.stream.Streams$ConcatSpliterator.forEachRemaining(Streams.java:735)
    at java.base/java.util.stream.Streams$ConcatSpliterator.forEachRemaining(Streams.java:734)
    at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762)
    at java.base/java.util.Optional.orElseGet(Optional.java:364)
    at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
    at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'dao.StudentDao' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1894)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1411)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1358)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:785)
    ... 21 more

四.解决方案

仔细检查项目后，发现dao层的位置放错了

应修改为：

最后也是完美解决：

总之不管遇到什么问题，都需要静下心来慢慢分析，任何人都会有出错误的时候，关键看怎么解决！！！不要畏惧报错！！