Autowire first look for type
if there is only type available in XML then it is going to autowire with
that type because there is only one bean – even though ID is different. If XML
has beans of same type more than one
time then it will through an exception. In this case you need to configure bean
ID which matches with setter method type.
Eg.
<bean id="circle"
class="org.yash.watertechsol.Circle">
</bean>
<bean id
="center"
class="org.yash.watertechsol.Point">
<property name="x"
value="0" />
<property name="y"
value="0" />
</bean>
<bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor">
</bean>
@Autowired
public void setCenter(Point
center) {
this.center = center;
}
Suppose if you are not able to change bean id because it is
used by some other resources, then you need to go with @Qualifer annotation below changes need to do.
1.
Remove DocType from xml
2.
Add below code
<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-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<bean id
="pointA"
class="org.yash.watertechsol.Point">
<qualifier value="circleRelated"></qualifier>
<property name="x"
value="0" />
<property name="y"
value="0" />
</bean>
<bean id="circle"
class="org.yash.watertechsol.Circle">
</bean>
<bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor">
</bean>
@Autowired
@Qualifier("circleRelated")
public void setCenter(Point
center) {
this.center = center;
}
Note: Instead of adding all the annotation beans in XML you
can configure all annotation using below config.
<context:annotation-config
/>
Or
<bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor">
</bean>
DrawingApp.java
package org.yash.watertechsol;
import org.springframework.context.support.AbstractApplicationContext;
import
org.springframework.context.support.ClassPathXmlApplicationContext;
public class DrawingApp {
public static void main(String[] args){
AbstractApplicationContext
context = new ClassPathXmlApplicationContext("spring.xml");
context.registerShutdownHook();
Shape shape =
(Shape)context.getBean("circle");
shape.draw();
}
}
Point.java
package org.yash.watertechsol;
public class Point {
private int x;
private int y;
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
}
Triangle.java
package org.yash.watertechsol;
public class Triangle implements Shape{
private Point pointA;
private Point pointB;
private Point pointC;
public Point
getPointA() {
return pointA;
}
public void setPointA(Point
pointA) {
this.pointA = pointA;
}
public Point
getPointB() {
return pointB;
}
public void setPointB(Point
pointB) {
this.pointB = pointB;
}
public Point
getPointC() {
return pointC;
}
public void setPointC(Point
pointC) {
this.pointC = pointC;
}
public void draw(){
System.out.println("Drawing
Triangle");
System.out.println("Point A
= (" + getPointA().getX()+", "+getPointA().getY()+")");
System.out.println("Point B
= (" + getPointB().getX()+", "+getPointB().getY()+")");
System.out.println("Point C
= (" + getPointC().getX()+", "+getPointC().getY()+")");
}
}
Shape.java
package org.yash.watertechsol;
public interface Shape {
public void draw();
}
Circle.java
package org.yash.watertechsol;
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("("+center.getX()+", "+center.getY()+")");
}
public Point
getCenter() {
return center;
}
@Autowired
@Qualifier("circleRelated")
public void setCenter(Point
center) {
this.center = center;
}
}
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"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<!--
<bean id="triangle" class="org.yash.watertechsol.Triangle">
<property
name="pointA" ref="pointA"></property>
<property
name="pointB" ref="pointB"></property>
<property
name="pointC" ref="pointC"></property>
</bean> -->
<bean id="circle"
class="org.yash.watertechsol.Circle">
</bean>
<bean id
="pointA"
class="org.yash.watertechsol.Point">
<qualifier value="circleRelated"></qualifier>
<property name="x"
value="0" />
<property name="y"
value="0" />
</bean>
<bean id
="pointB"
class="org.yash.watertechsol.Point">
<property name="x"
value="-20" />
<property name="y"
value="0" />
</bean>
<bean id
="pointC"
class="org.yash.watertechsol.Point">
<property name="x"
value="0" />
<property name="y"
value="20" />
</bean>
<!-- <bean
class="org.springframework.beans.factory.annotation.RequiredAnnotationBeanPostProcessor"></bean>
-->
<bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor">
</bean>
</beans>
|
1
|
@Required
The @Required annotation applies to bean property setter methods. |
|
2
|
@Autowired
The @Autowired annotation can apply to bean property setter methods, non-setter methods, constructor and properties. |
|
3
|
@Qualifier
The @Qualifier annotation along with @Autowired can be used to remove the confusion by specifiying which exact bean will be wired. |
|
4
|
JSR-250
Annotations
Spring supports JSR-250 based annotations which include @Resource, @PostConstruct and @PreDestroy annotations. |
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