Autowired和Qualifier Java批注

Question

我對此注釋有疑問。

這是我的Circle課程：

public class Circle implements Shape {

    private Point center;

    public Point getCenter() {
        return center;
    }

    @Autowired
    @Qualifier("circleRelated")
    public void setCenter(Point center) {
        this.center = center;
    }

    @Override
    public void draw() {
        System.out.println("Drawing cicrle " + center.getX() + ", " + center.getY());
    }
}

這是我的spring.xml文件：

<?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="pointA" class="com.majewski.javabrains.Point">
        <qualifier value="circleRelated" />
        <property name="x" value ="0" />
        <property name="y" value ="0" />
    </bean>

    <bean id="pointB" class="com.majewski.javabrains.Point">
        <property name="x" value ="0" />
        <property name="y" value ="1" />
    </bean>

    <bean id="pointC" class="com.majewski.javabrains.Point">
        <property name="x" value ="0" />
        <property name="y" value ="20" />
    </bean>

    <bean id="circle" class="com.majewski.javabrains.Circle" />

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

</beans>

這是我的主要方法：

public static void main(String[] args) {
        AbstractApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");
        context.registerShutdownHook();

        Shape shape = (Shape) context.getBean("circle");
        shape.draw();
    }

我收到一個錯誤：

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 com.majewski.javabrains.Circle.setCenter(com.majewski.javabrains.Point);
    nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.majewski.javabrains.Point] is defined:
    expected single matching bean but found 3: pointA,pointB,pointC

我已經在“ pointA” bean中添加了選項卡，所以我不明白我的程序出了什么問題。 有人可以向我解釋嗎？

Answer 1

我想你不見了

<context:annotation-config  />

因此，在您的Spring上下文中，XML和@Qualifier("circleRelated")被忽略。

-編輯-

當然，為了使用它，您需要擴展名稱空間定義...

<beans 
    ...
    xmlns:context="http://www.springframework.org/schema/context"
    ...
  xsi:schemaLocation=".... http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-YOUR-SPRING-VERSION-HERE.xsd">

Answer 2

很好，問題出在限定符@Qualifier("circleRelated") ，因為您嘗試綁定名稱為circleRelated的bean，但是在spring-conf.xml中，您僅聲明了3個名稱為pointA，pointB，pointC的點，因此無法匹配並注入實例，因此可以將@Qualifier("circleRelated")更改為@Qualifier("circleRelated") @Qualifier("pointA")或使用<bean id="circleRelated" class="com.majewski.javabrains.Point">在xml中聲明一個bean <bean id="circleRelated" class="com.majewski.javabrains.Point">