ByType mode of Autowiring

Autowire-ByType

>> It performs setter injection
>> For this, all target class property type and dependent class must match or must be compatible..
>> There is possibility of getting ambiguity problem.
>> If ambiguity problem occures, it can be resolved by using

1. primary="true" in one of the dependent bean class configuration(In <bean> tag).
2. default-autowire-candidate="beanId" int beans tag <beans>

>> It use 0-param constructor to create the object..

TravelAgent.java:

1. package com.nt.beans;
2. 
   
3. public class TravelAgent {
4. private TourPlan tp;
5. 
   
6. public TravelAgent() {
7. System.out.println("TravelAgent::0-param constructor");
8. }
9. 
   
10. public void setTp(TourPlan tp) {
11. System.out.println("TravelAgent.setTp()");
12. this.tp = tp;
13. }
14. 
    
15. @Override
16. public String toString() {
17. return "TravelAgent [tp=" + tp + "]";
18. }
19. }

TourPlan.java:

2. package com.nt.beans;
3. 
   
4. import java.util.Arrays;
5. 
   
6. public class TourPlan {
7. private String places[];
8. 
   
9. public void setPlaces(String[] places) {
10. this.places = places;
11. }
12. 
    
13. @Override
14. public String toString() {
15. return "TourPlan [places=" + Arrays.toString(places) + "]";
16. }
17. }

applicationContext.xml:

2. <?xml version="1.0" encoding="UTF-8"?>
3. <beans xmlns="http://www.springframework.org/schema/beans"
4. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
5. xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">
7. <bean id="tp" class="com.nt.beans.TourPlan">
8. <property name="places">
9. <array>
10. <value>Simla</value>
11. <value>Goa</value>
12. <value>Delhi</value>
13. </array>
14. </property>
15. </bean>
16. <bean id="ta" class="com.nt.beans.TravelAgent" autowire="byName"/>
17. </beans>

AutowireByTypeTest.java:

2. package com.nt.test;
3. 
   
4. import org.springframework.context.ApplicationContext;
5. import org.springframework.context.support.AbstractApplicationContext;
6. import org.springframework.context.support.ClassPathXmlApplicationContext;
7. import com.nt.beans.TravelAgent;
8. 
   
9. public class AutowireByTypeTest {
10. public static void main(String[] args) {
11. ApplicationContext ctx=null;
12. TravelAgent ta=null;
13. ctx=new ClassPathXmlApplicationContext("com/nt/cfgs/applicationContext.xml");
14. ta=ctx.getBean("ta",TravelAgent.class);
15. System.out.println(ta);
16. ((AbstractApplicationContext) ctx).close();
17. }
18. }