为什么我收到“无法加载的ApplicationContext”春，JUnit的使用JavaConfig

Question

为什么会出现“无法加载的ApplicationContext”春，JUnit的使用JavaConfig

这里是我的测试类：

@RunWith(SpringJUnit4ClassRunner.class) 
@ContextConfiguration(classes = HelloWorldConfig.class) 
public class TestApp 
{ 

    @Test 
    public void testBean() 
    { 
     ApplicationContext context = new AnnotationConfigApplicationContext(HelloWorldConfig.class); 

     HelloWorld helloWorld = context.getBean(HelloWorld.class); 
     helloWorld.setMessage("I am in Staten Island, New York"); 

     Assert.assertEquals(helloWorld.getMessage(), "I am in Staten Island, New York"); 
    } 
} 

Answer 1

堆栈跟踪显示问题：

java.lang.IllegalStateException: Failed to load ApplicationContext at 
org.springframework.test.context.CacheAwareContextLoaderDelegate.loadContext(CacheAwareContextLoaderDelegate.java:99) 
    at 
org.springframework.test.context.TestContext.getApplicationContext(TestContext.java:122) 
    at 
org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:109) 
    at 
org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:75) 
    at 
org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:312) 
    at 
org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:211) at 
org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:288) 
    at 
org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15) 
    at 
org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:284) 
    at 
org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:231) 
    at 
org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:88) 
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193) at 
org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)  at 
org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191) at 
org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)  at 
org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184) at 
org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) 
    at 
org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71) 
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236) at 
org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:174) 
    at org.junit.runner.JUnitCore.run(JUnitCore.java:157) at 
com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:77) 
    at 
com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:195) 
    at 
com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:63) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at 
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
    at 
com.intellij.rt.execution.application.AppMain.main(AppMain.java:120) 
Caused by: org.springframework.beans.factory.BeanCreationException: 
Error creating bean with name 'messageService': Injection of autowired 
dependencies failed; nested exception is 
org.springframework.beans.factory.BeanCreationException: Could not 
autowire field: private 
com.johnathanmarksmith.hellospring.dao.MessageDao 
com.johnathanmarksmith.hellospring.service.MessageServiceImpl.messageDao; 
nested exception is 
org.springframework.beans.factory.NoSuchBeanDefinitionException: No 
qualifying bean of type 
[com.johnathanmarksmith.hellospring.dao.MessageDao] found for 
dependency: expected at least 1 bean which qualifies as autowire 
candidate for this dependency. Dependency annotations: 
{@org.springframework.beans.factory.annotation.Autowired(required=true)} 
    at 
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:288) 
    at 
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1122) 
    at 
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:522) 
    at 
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:461) 
    at 
org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295) 
    at 
org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223) 
    at 
org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292) 
    at 
org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194) 
    at 
org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:626) 
    at 
org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932) 
    at 
org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479) 
    at 
org.springframework.test.context.support.AbstractGenericContextLoader.loadContext(AbstractGenericContextLoader.java:120) 
    at 
org.springframework.test.context.support.AbstractGenericContextLoader.loadContext(AbstractGenericContextLoader.java:60) 
    at 
org.springframework.test.context.support.AbstractDelegatingSmartContextLoader.delegateLoading(AbstractDelegatingSmartContextLoader.java:100) 
    at 
org.springframework.test.context.support.AbstractDelegatingSmartContextLoader.loadContext(AbstractDelegatingSmartContextLoader.java:248) 
    at 
org.springframework.test.context.CacheAwareContextLoaderDelegate.loadContextInternal(CacheAwareContextLoaderDelegate.java:64) 
    at 
org.springframework.test.context.CacheAwareContextLoaderDelegate.loadContext(CacheAwareContextLoaderDelegate.java:91) 
    ... 28 more Caused by: 
org.springframework.beans.factory.BeanCreationException: Could not 
autowire field: private 
com.johnathanmarksmith.hellospring.dao.MessageDao 
com.johnathanmarksmith.hellospring.service.MessageServiceImpl.messageDao; 
nested exception is 
org.springframework.beans.factory.NoSuchBeanDefinitionException: No 
qualifying bean of type 
[com.johnathanmarksmith.hellospring.dao.MessageDao] found for 
dependency: expected at least 1 bean which qualifies as autowire 
candidate for this dependency. Dependency annotations: 
{@org.springframework.beans.factory.annotation.Autowired(required=true)} 
    at 
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:514) 
    at 
org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87) 
    at 
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:285) 
    ... 44 more Caused by: 
org.springframework.beans.factory.NoSuchBeanDefinitionException: No 
qualifying bean of type 
[com.johnathanmarksmith.hellospring.dao.MessageDao] found for 
dependency: expected at least 1 bean which qualifies as autowire 
candidate for this dependency. Dependency annotations: 
{@org.springframework.beans.factory.annotation.Autowired(required=true)} 
    at 
org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:986) 
    at 
org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:856) 
    at 
org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:768) 
    at 
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:486) 
    ... 46 more 

日志消息说，你还没有定义MessageDAO：

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.johnathanmarksmith.hellospring.dao.MessageDao] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)} 

这个bean是在MessageServiceImpl自动装配这是在HelloConfig.class定义但不是在你的配置类

此外，使用SpringJUnit4ClassRunner.class当你没有必要在你的测试创建的ApplicationContext，只是自动装配HelloWorld加入你的JUnit