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老師,求分析異常原因,我把@Bean修改為這樣,還會(huì)拋出異常,代碼如下

//測試類不動(dòng)
@Test
public?void?testG(){
????Store?store?=?super.getBean("stringStore");
}
//StoreConfig類中的@Bean
@Autowired
private?Store<String>?s1;
@Autowired
private?Store<Integer>?s2;
@Bean
public?StringStore?stringStore(){
????System.out.println("s1"+s1.getClass().getName());
????System.out.println("s2"+s2.getClass().getName());
????return?new?StringStore();
}
@Bean
public?IntegerStore?integerStore(){
????return?new?IntegerStore();
}
//然后拋出的異常和老師講解的異常一樣,我這樣改了,s1,s2都沒指定到多個(gè)bean的實(shí)例對象啊


正在回答

9 回答

因?yàn)閟tringStore()方法執(zhí)行的目的就是為了實(shí)例化s1,在方法體中使用s1,此時(shí)還沒有實(shí)例化完成,所以要報(bào)空指針異常。

1 回復(fù) 有任何疑惑可以回復(fù)我~

你這種需要添加 過濾@Autowiere("mingzi")就沒問題了 至于老師的為什么不報(bào)錯(cuò) 可能是版本問題?

0 回復(fù) 有任何疑惑可以回復(fù)我~

......你這么寫,當(dāng)執(zhí)行到??System.out.println("s1"+s1.getClass().getName())這句的時(shí)候,

return?new?StringStore();這句還沒執(zhí)行到啊 也就是說 此時(shí)IOC容器中連StringStore這個(gè)bean都是不存在的,

s1自然也是個(gè)空的嘍,那你要它怎么輸出,自然是個(gè)空指針嘍

1 回復(fù) 有任何疑惑可以回復(fù)我~

可以這樣寫 stringStoreTest:

@Bean(name="stringStoreTest")

public StoreConfig stringStoreTest(){

? ? System.out.println("s1:"+s1.getClass().getName());

? ? System.out.println("s2:"+s2.getClass().getName());

? ? ?return new StoreConfig();

}

測試類為:

@Test

public void testG() {

super.getBean("stringStoreTest");

}

結(jié)果跟老師顯示的一樣!否則會(huì)報(bào) s1,s2 變量空指針異常!

2 回復(fù) 有任何疑惑可以回復(fù)我~

我也是啊 怎么解決呢?

0 回復(fù) 有任何疑惑可以回復(fù)我~

我也碰到這個(gè)問題了, 修改測試類的返回類型不能為Store或或其子類即可. 我用的是Spring4.2.6版本

0 回復(fù) 有任何疑惑可以回復(fù)我~
#1

笑傲獨(dú)行俠

兄弟,我也是這樣,為啥啊
2017-12-06 回復(fù) 有任何疑惑可以回復(fù)我~

?System.out.println("s1"+s1.getClass().getName());

?System.out.println("s2"+s2.getClass().getName());

這兩個(gè)地方是需要對象不能為空的,而調(diào)用的時(shí)候是注解自動(dòng)注入的,此時(shí)還沒有注入,所以會(huì)出錯(cuò)誤,你可以先去掉這兩處,就可以通過;另外你如果想看一下注入是否成功,可以將成員變量變?yōu)楣驳?,然后去訪問

1 回復(fù) 有任何疑惑可以回復(fù)我~

你的spring版本是3 還是4,3好像不支持泛型。。。

0 回復(fù) 有任何疑惑可以回復(fù)我~
org.springframework.beans.factory.BeanCreationException:?Error?creating?bean?with?name?'storeConfig':?Injection?of?autowired?dependencies?failed;?nested?exception?is?org.springframework.beans.factory.BeanCreationException:?Could?not?autowire?field:?private?com.imooc.beanannotation.javabased.Store?com.imooc.beanannotation.javabased.StoreConfig.s1;?nested?exception?is?org.springframework.beans.factory.BeanCreationException:?Error?creating?bean?with?name?'stringStore'?defined?in?class?path?resource?[com/imooc/beanannotation/javabased/StoreConfig.class]:?Instantiation?of?bean?failed;?nested?exception?is?org.springframework.beans.factory.BeanDefinitionStoreException:?Factory?method?[public?com.imooc.beanannotation.javabased.StringStore?com.imooc.beanannotation.javabased.StoreConfig.stringStore()]?threw?exception;?nested?exception?is?java.lang.NullPointerException
	at?org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:292)
	at?org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1185)
	at?org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
	at?org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
	at?org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:304)
	at?org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
	at?org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300)
	at?org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
	at?org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:703)
	at?org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:760)
	at?org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
	at?org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
	at?org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:93)
	at?com.imooc.test.UnitTestBase.before(UnitTestBase.java:27)
	at?sun.reflect.NativeMethodAccessorImpl.invoke0(Native?Method)
	at?sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at?sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at?java.lang.reflect.Method.invoke(Method.java:606)
	at?org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
	at?org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
	at?org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
	at?org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:27)
	at?org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:30)
	at?org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
	at?org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
	at?org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
	at?org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
	at?org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
	at?org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
	at?org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
	at?org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
	at?org.junit.runners.ParentRunner.run(ParentRunner.java:300)
	at?org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
	at?org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
	at?org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
	at?org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
	at?org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
	at?org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused?by:?org.springframework.beans.factory.BeanCreationException:?Could?not?autowire?field:?private?com.imooc.beanannotation.javabased.Store?com.imooc.beanannotation.javabased.StoreConfig.s1;?nested?exception?is?org.springframework.beans.factory.BeanCreationException:?Error?creating?bean?with?name?'stringStore'?defined?in?class?path?resource?[com/imooc/beanannotation/javabased/StoreConfig.class]:?Instantiation?of?bean?failed;?nested?exception?is?org.springframework.beans.factory.BeanDefinitionStoreException:?Factory?method?[public?com.imooc.beanannotation.javabased.StringStore?com.imooc.beanannotation.javabased.StoreConfig.stringStore()]?threw?exception;?nested?exception?is?java.lang.NullPointerException
	at?org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:508)
	at?org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
	at?org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:289)
	...?37?more
Caused?by:?org.springframework.beans.factory.BeanCreationException:?Error?creating?bean?with?name?'stringStore'?defined?in?class?path?resource?[com/imooc/beanannotation/javabased/StoreConfig.class]:?Instantiation?of?bean?failed;?nested?exception?is?org.springframework.beans.factory.BeanDefinitionStoreException:?Factory?method?[public?com.imooc.beanannotation.javabased.StringStore?com.imooc.beanannotation.javabased.StoreConfig.stringStore()]?threw?exception;?nested?exception?is?java.lang.NullPointerException
	at?org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:597)
	at?org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1094)
	at?org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:989)
	at?org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:504)
	at?org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
	at?org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:304)
	at?org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
	at?org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300)
	at?org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
	at?org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1017)
	at?org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:960)
	at?org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:858)
	at?org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:480)
	...?39?more
Caused?by:?org.springframework.beans.factory.BeanDefinitionStoreException:?Factory?method?[public?com.imooc.beanannotation.javabased.StringStore?com.imooc.beanannotation.javabased.StoreConfig.stringStore()]?threw?exception;?nested?exception?is?java.lang.NullPointerException
	at?org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:188)
	at?org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:586)
	...?51?more
Caused?by:?java.lang.NullPointerException
	at?com.imooc.beanannotation.javabased.StoreConfig.stringStore(StoreConfig.java:52)
	at?com.imooc.beanannotation.javabased.StoreConfig$$EnhancerBySpringCGLIB$$dac9b232.CGLIB$stringStore$0(<generated>)
	at?com.imooc.beanannotation.javabased.StoreConfig$$EnhancerBySpringCGLIB$$dac9b232$$FastClassBySpringCGLIB$$198dfac8.invoke(<generated>)
	at?org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228)
	at?org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:312)
	at?com.imooc.beanannotation.javabased.StoreConfig$$EnhancerBySpringCGLIB$$dac9b232.stringStore(<generated>)
	at?sun.reflect.NativeMethodAccessorImpl.invoke0(Native?Method)
	at?sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at?sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at?java.lang.reflect.Method.invoke(Method.java:606)
	at?org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:166)
	...?52?more


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老師,求分析異常原因,我把@Bean修改為這樣,還會(huì)拋出異常,代碼如下

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