使用限定符注入自动连接的依赖项失败

Question

我已经尝试了所有可以在任何地方找到的选项,我查看了之前就该主题提出的所有问题并尝试了解决方案,但没有任何效果,我得到的就是这个错误.

错误

INFO: Loading XML bean definitions from class path resource [spring.xml]
Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'circle': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire method: public void spring.springdemo.Circle.setCenter(spring.springdemo.Point); nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [spring.springdemo.Point] is defined: expected single matching bean but found 3: pointA,pointB,pointC
    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$1.getObject(AbstractBeanFactory.java:304)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:700)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:760)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)
    at spring.springdemo.DrawingApp.main(DrawingApp.java:10)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire method: public void spring.springdemo.Circle.setCenter(spring.springdemo.Point); nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [spring.springdemo.Point] is defined: expected single matching bean but found 3: pointA,pointB,pointC
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredMethodElement.inject(AutowiredAnnotationBeanPostProcessor.java:596)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:289)
    ... 13 more
Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [spring.springdemo.Point] is defined: expected single matching bean but found 3: pointA,pointB,pointC
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:967)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:855)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredMethodElement.inject(AutowiredAnnotationBeanPostProcessor.java:553)
    ... 15 more

我在这个例子中创建的文件如下.

spring.xml 这是架构定义

<?xml version="1.0" encoding="UTF-8"?>

    <beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd">

这是我想申请自动装配的地方.

 <bean id="circle" class="spring.springdemo.Circle">

</bean>

<bean id="pointA" class="spring.springdemo.Point">
    <qualifier value="CircleRelated"/>
    <property name="x" value="0"/>
    <property name="y" value="0"/>
</bean>
<bean id="pointB" class="spring.springdemo.Point">
        <property name="x" value="-20"/>
        <property name="y" value="0"/>
    </bean>
    <bean id="pointC" class="spring.springdemo.Point">
        <property name="x" value="20"/>
        <property name="y" value="0"/>
    </bean>

我添加了这些类.

    <bean class="org.springframework.beans.factory.annotation.QualifierAnnotationAutowireCandidateResolver"/>
    <bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor"/>

Circle.java 类,该对象将由autowire填充

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;


public class Circle implements Shape{
    private Point center;

    @Override
    public void draw() {
        System.out.println("Drawing Circle");
        System.out.println("Point is : ("+center.getX()+", "+center.getY()+")");
    }
    public Point getCenter() {
        return center;
    }
    @Autowired
    @Qualifier("CircleRelated")
    public void setCenter(Point center) {
        this.center = center;
    }

}

Answer 1

<qualifier value="CircleRelated"/>我建议您从 xml 中删除并直接从 id 注入依赖项。xml中的id在大​​多数情况下就足够了，限定符只能用于特定情况。约定是使用小写字母作为 id 或限定符的第一个字母。

因此，通过现有 idCircleRelated进行更改，例如,或@Qualifier("CircleRelated")@Qualifier("pointA")@Qualifier("pointB")@Qualifier("pointC")