Spring Autowiring by Name

In Spring "Autowire byName means" autowiring is done by property name. Spring container looks at the properties of the beans on which autowire attribute is set to byName in the XML configuration file. It then tries to match and wire its properties with the beans defined by the same names in the configuration file.
Spring Autowiring by Name

For example, if a "triangle" bean exposes an "pointA, pointB & pointC" properties, Spring will find these point bean("pointA, pointB & pointC") in current container and wire it automatically. And if no matching found, just do nothing.

Popular Tutorials

You can enable this feature via autowire="byName" like below :

Normally, you wire the bean explicitly, via ref attribute like this :
<bean class="com.dineshonjava.sdnext.autoWiring.tutorial.Triangle" id="triangle">
   <property name="pointA" ref="pointA"></property>
   <property name="pointB" ref="pointB"></property>
   <property name="pointC" ref="pointC"></property>
</bean>
<bean class="com.dineshonjava.sdnext.autoWiring.tutorial.Point" id="pointA">
   <property name="x" value="0"></property>
   <property name="y" value="0"></property>
</bean>
  
<bean class="com.dineshonjava.sdnext.autoWiring.tutorial.Point" id="pointB">
   <property name="x" value="-20"></property>
   <property name="y" value="0"></property>
</bean>
  
<bean class="com.dineshonjava.sdnext.autoWiring.tutorial.Point" id="pointC">
   <property name="x" value="20"></property>
   <property name="y" value="0"></property>
</bean>

With autowire by name enabled, you do not need to declares the property tag anymore. As long as the "pointA, pointB & pointC" beans are same name as the property of "triangle" bean, which is "pointA, pointB & pointC", Spring will wire it automatically.

Lets see Exaple
Triangle.java
package com.dineshonjava.sdnext.autoWiring.tutorial;

public class Triangle 
{
 private Point pointA;
 private Point pointB;
 private Point pointC;
 
 /**
  * @param pointA the pointA to set
  */
 public void setPointA(Point pointA) {
  this.pointA = pointA;
 }

 /**
  * @param pointB the pointB to set
  */
 public void setPointB(Point pointB) {
  this.pointB = pointB;
 }

 /**
  * @param pointC the pointC to set
  */
 public void setPointC(Point pointC) {
  this.pointC = pointC;
 }

 public void draw()
 {
  System.out.println("PointA is ("+pointA.getX()+", "+pointA.getY()+")");
  System.out.println("PointB is ("+pointB.getX()+", "+pointB.getY()+")");
  System.out.println("PointC is ("+pointC.getX()+", "+pointC.getY()+")");
 }
}
Point.java
package com.dineshonjava.sdnext.autoWiring.tutorial;

public class Point
{
 private int x;
 private int y;
 /**
  * @return the x
  */
 public int getX() {
  return x;
 }
 /**
  * @param x the x to set
  */
 public void setX(int x) {
  this.x = x;
 }
 /**
  * @return the y
  */
 public int getY() {
  return y;
 }
 /**
  * @param y the y to set
  */
 public void setY(int y) {
  this.y = y;
 }
}
spring.xml
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.springframework.org/schema/beans" xsi:schemalocation="http://www.springframework.org/schema/beans  
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

<bean autowire="byName" class="com.dineshonjava.sdnext.autoWiring.tutorial.Triangle" id="triangle">
  </bean>
 <bean class="com.dineshonjava.sdnext.autoWiring.tutorial.Point" id="pointA">
  <property name="x" value="0"></property>
  <property name="y" value="0"></property>
 </bean>
  
 <bean class="com.dineshonjava.sdnext.autoWiring.tutorial.Point" id="pointB">
  <property name="x" value="-20"></property>
  <property name="y" value="0"></property>
 </bean>
  
 <bean class="com.dineshonjava.sdnext.autoWiring.tutorial.Point" id="pointC">
  <property name="x" value="20"></property>
  <property name="y" value="0"></property>
 </bean>
</beans>
DrawingApp.java
package com.dineshonjava.sdnext.autoWiring.tutorial;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;


/**
 * @author Dinesh Rajput
 *
 */
public class DrawingApp 
{
 /**
  * @param args
  */
 public static void main(String[] args) 
 {
ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");
  Triangle triangle = (Triangle) context.getBean("triangle");
  triangle.draw();
 }
}

Now run this application and get following output on the console.
Output:
Jun 25, 2012 7:55:23 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
INFO: Loading XML bean definitions from class path resource [spring.xml]
Jun 25, 2012 7:55:24 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@1592174: defining beans [triangle,pointA,pointB,pointC]; root of factory hierarchy
PointA is (0, 0)
PointB is (-20, 0)
PointC is (20, 0)

Spring Related Topics you may like
  1. Spring Interview Questions and Answers
  2. Spring AOP Interview Questions and Answers
  3. Spring MVC Interview Questions
  4. Spring Security Interview Questions and Answers
  5. Spring REST Interview Questions and Answers
  6. Spring Boot Interview Questions and Answers
  7. Spring Boot Microservices Interview Questions and Answers
  8. Dependency Injection (DI) in Spring
  9. Spring IoC Container
  10. What is Bean Factory in Spring
  11. ApplicationContext in Spring
  12. Bean Autowiring in Spring
  13. Spring Bean Scopes
  14. Create Custom Bean Scope in Spring Example
  15. Using ApplicationContextAware in Spring
  16. Spring Bean Life Cycle and Callbacks
  17. BeanPostProcessor in Spring
  18. BeanFactoryPostProcessor in Spring
  19. Annotations in Spring and Based Configuration
  20. Spring JSR-250 Annotations
  21. JSR 330 Annotations in Spring
  22. Spring @Component, @Repository, @Service and @Controller Stereotype Annotations
  23. Method injection with Spring using Lookup method property
  24. Spring AOP-Introduction to Aspect Oriented Programming
  25. @Aspect Annotation in Spring
  26. Spring AOP AspectJ @Before Annotation Advice Example
  27. Spring AOP Before Advice Example using XML Config
  28. Spring AOP AspectJ @After Annotation Advice Example
  29. Spring AOP After Advice Example using XML Config
  30. Spring AOP AspectJ @AfterReturning Annotation Advice Example
  31. Spring AOP After-Returning Advice Example using XML Config
  32. Spring AOP AspectJ @AfterThrowing Annotation Advice Example
  33. Spring AOP After Throwing Advice Example using XML Config
  34. Spring AOP AspectJ @Around Annotation Advice Example
  35. Spring AOP Around Advice Example using XML Config
  36. Spring AOP Proxies in Spring
  37. Spring AOP Transaction Management in Hibernate
  38. Spring Transaction Management
  39. Spring Declarative Transaction Management Example
  40. Spring AOP-Ordering of Aspects with Example
  41. Spring Security Java Based Configuration with Example
  42. Spring Security XML Namespace Configuration Example

Understanding Bean Scopes |index| Using ApplicationContextAware in Spring



Labels: