为什么 @Autowired注解失败

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'com.example.demo.dao.AreaDaoTest': Unsatisfied dependency expressed through field 'areaDao'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.example.demo.dao.AreaDao' 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.inject(AutowiredAnnotationBeanPostProcessor.java:586)

at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90)

at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:372)

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1341)

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireBeanProperties(AbstractAutowireCapableBeanFactory.java:393)

at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:118)

at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:83)

at org.springframework.boot.test.autoconfigure.SpringBootDependencyInjectionTestExecutionListener.prepareTestInstance(SpringBootDependencyInjectionTestExecutionListener.java:44)

at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:246)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:227)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:289)

at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:291)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:246)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)

at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)

at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)

at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)

at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)

at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)

at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)

at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)

at org.junit.runners.ParentRunner.run(ParentRunner.java:363)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)

at org.junit.runner.JUnitCore.run(JUnitCore.java:137)

at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)

at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)

at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)

at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.example.demo.dao.AreaDao' 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:1506)

at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1101)

at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1062)

at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:583)

... 28 more

public interface AreaDao {
    List<Area> queryArea();
    Area queryAreaById(int areaId);
    int insertArea(Area area);
    int updateArea(Area area);
    int deleteArea(int area);
}