Spring 4.1 @Qualifier不起作用 [英] Spring 4.1 @Qualifier doesnt'work
本文介绍了Spring 4.1 @Qualifier不起作用的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有这样的类，xml配置文件和错误堆栈跟踪.我不知道为什么@Qualifier无法正常工作.我看到他甚至什么都不做的错误.
I have classes, xml configuration file and error stack trace like this. I have no idea why @Qualifier doesn't work. I see on errors that he don't even do anything.
狗
public class SimpleDog implements Dog {
@Autowired
@Qualifier("small")
private Size size;
private String name;
public Size getSize() {
return size;
}
public void setSize(Size size) {
this.size = size;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public void giveSound() {
System.out.println("dog size is : width : (" + size.getWidth() + ") , height : (" + size.getHeight() + ")");
System.out.println("dog's name : " + name);
}
}
测试班
public class Test2 {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("spring-test2.xml");
SimpleDog dog = (SimpleDog) context.getBean("dog");
dog.giveSound();
}
}
spring.xml
spring.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="dog" class="com.tests.test2.SimpleDog">
<property name="name" value="Puppy" />
</bean>
<bean id="size1" class="com.tests.test2.Size">
<qualifier value="small"/>
<property name="height" value="2"/>
<property name="width" value="1"/>
</bean>
<bean id="size2" class="com.tests.test2.Size">
<qualifier value="large"/>
<property name="height" value="20"/>
<property name="width" value="10"/>
</bean>
<bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor"/>
</beans>
错误堆栈跟踪
WARNING: Exception encountered during context initialization - cancelling refresh attempt
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dog': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.tests.test2.Size com.tests.test2.SimpleDog.size; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.tests.test2.Size] is defined: expected single matching bean but found 2: size1,size2
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1204)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:538)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:229)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:725)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:757)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480)
at org.springframework.context.support.FileSystemXmlApplicationContext.<init>(FileSystemXmlApplicationContext.java:140)
at org.springframework.context.support.FileSystemXmlApplicationContext.<init>(FileSystemXmlApplicationContext.java:84)
at pl.patrykgryta.test2.Test2.main(Test2.java:12)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.tests.test2.Size com.tests.test2.SimpleDog.size; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.tests.test2.Size] is defined: expected single matching bean but found 2: size1,size2
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:555)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:331)
... 18 more
Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.tests.test2.Size] is defined: expected single matching bean but found 2: size1,size2
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1016)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:904)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:527)
... 20 more
Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dog': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.tests.test2.Size com.tests.test2.SimpleDog.size; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.tests.test2.Size] is defined: expected single matching bean but found 2: size1,size2
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1204)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:538)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:229)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:725)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:757)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480)
at org.springframework.context.support.FileSystemXmlApplicationContext.<init>(FileSystemXmlApplicationContext.java:140)
at org.springframework.context.support.FileSystemXmlApplicationContext.<init>(FileSystemXmlApplicationContext.java:84)
at pl.patrykgryta.test2.Test2.main(Test2.java:12)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.tests.test2.Size com.tests.test2.SimpleDog.size; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.tests.test2.Size] is defined: expected single matching bean but found 2: size1,size2
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:555)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:331)
... 18 more
Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.tests.test2.Size] is defined: expected single matching bean but found 2: size1,size2
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1016)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:904)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:527)
... 20 more
需要帮助
推荐答案
@Qualifier用于通过其名称或ID引用bean.由于无法找到名称或ID为"small"的xml条目，因此它尝试按类型进行匹配，并找到了两个Size实例.
@Qualifier is used to reference a bean by its name or id. Since it can't find an xml entry that has a name or id of 'small' it tries to match by type, of which it found two instances of Size.
以下方法将起作用:
<bean id="small" class="com.tests.test2.Size">
<property name="height" value="2"/>
<property name="width" value="1"/>
</bean>
尽管看起来您希望将Size实例视为预配置的bean.如果是这种情况，您可以在xml文件中声明Dog的实例，然后引用Size bean ...类似这样:
Though it appears you would like to treat instances of Size as pre-configured beans. If that were the case you could declare instances of Dog in your xml file and refer to Size beans ... something like this:
<bean id="rex" class="com.tests.test2.SimpleDog">
<property name="name" value="Puppy" />
<property name="size" ref="size1"/>
</bean>
这篇关于Spring 4.1 @Qualifier不起作用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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