Auto wiring with qualifier annotation - spring

Question

I am trying to auto wire my Circle class. I am using a qualifier in order for Spring to able to distinguish between the two Point class beans i have created a qualifier.
public class Circle{
private Point center;
#Autowired
#Qualifier("circleRelated")
public void setCenter(Point center) {
this.center = center;
}
public void draw() {
System.out.println("Drawing Circle");
System.out.println("Centre point is " + center.getX());
}
}
The Point class is as follows
public class Point {
private int x;
public int getX() { return x; }
public void setX(int x) { this.x = x;}
}
The beans.xml is
<?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="circle" class="com.example.Circle"/>
<bean id="pointA" class="com.example.Point">
<qualifier value="circleRelated" />
<property name="x" value="0"/>
<property name="y" value="0"/>
</bean>
<bean id="pointB" class="com.example.Point">
<property name="x" value="-20"/>
<property name="y" value="0"/>
</bean>
<bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor"/>
</beans>
My main class is
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
#SpringBootApplication
public class AutowiredAnnotationApplication {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
Circle circle = (Circle) context.getBean("circle");
circle.draw();
}
}
The error I get is
Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.example.Point] is defined: expected single matching bean but found 2: pointA,pointB
Why is spring unable to autowire the bean with the given qualifier?

Answer 1

You have to remove this line from your beans.xml:
<bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor"/>
For some reason, it is meddling with your otherwise correct configuration.

Answer 2

The #Qualifier gets the bean id as value. So you have to use "pointA" or "pointB"
public class Circle{
private Point center;
#Autowired
#Qualifier("pointA")
public void setCenter(Point center) {
this.center = center;
}
public void draw() {
System.out.println("Drawing Circle");
System.out.println("Centre point is " + center.getX());
}
}
In general if you skip the #Qualifier - you autowire by type. That means "search in the Spring context a bean of that type and throw an exception if none or more than one is found".
If you add the #Qualifier("someName") that means - "search in the Spring context a bean of that type and with that name and throw an exception if none is found"
Edit:
Take a look at this. I don't think that you need tag at all.
If you wan't to inject some bean using #Autowired the #Qualifier needs the bean id as it's value. For example #Qualifier("pointA") will require a bean with id: pointA.
If you want to inject the bean using only xml you can use ref. You don't need Qualifier for that, only for autowireing.
<?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="circle" class="com.example.Circle">
<property name="center" ref="pointA"/>
</bean>
<bean id="pointA" class="com.example.Point">
<qualifier value="circleRelated" />
<property name="x" value="0"/>
<property name="y" value="0"/>
</bean>
<bean id="pointB" class="com.example.Point">
<property name="x" value="-20"/>
<property name="y" value="0"/>
</bean>
</beans>
Edit 2:
See this. I believe that the qualifier tag is taken into account only if you skip the bean id, otherwise the bean id is used.