Quick to the point introduction to Spring Framework

It is same as the concept of Java inner classes where user can define a bean inside another bean. A <bean/> element within the <constructor-arg/> or <property/> elements is called inner bean. The characteristics of Spring inner beans:

• Inner bean is defined inside the context of its enclosing bean.
• Inner bean does not have an id associated with it user can provide an id.
• To declare an inner bean whenever a bean does not need to be shared with other beans.

Syntax:

<?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-3.0.xsd">

   <bean id="outerBean" class="...">
      <property name="target">
         <bean id="innerBean" class="..."/>
      </property>
   </bean>

</beans>

Example:

Java file: Student

package pack1;  
public class Student {  
private Student_Details  stud;  

    public void setName(Student stud) {
      System.out.println("Inside setName" );
      this.stud = stud;
   }

    public Student getName() {
      return stud;
   }
    public void display(){
      stud.Stud_Address();
   }
}  

Java file: Student_Details

package pack1;  

public class Student_Details {  
  
    public Student_Details (){
      System.out.println("Inside Student_Details  constructor" );
   }
   public void Stud_Address(){
      System.out.println("Inside Stud_Address");
    }
}  

Java file: ExmTest

package pack1;  
  
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
  
public class ExmTest {  
  public static void main(String[] args) {  
      ApplicationContext cont = new ClassPathXmlApplicationContext("Beans.xml");
      Student st = (Student) cont.getBean("studentBean");
      st. Stud_Address();
  }  
}  

The configuration file is Beans.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"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

   <bean id="studentBean" class="pack1.Student">
      <property name="stud">
         <bean id=" Student_Details" class="pack1. Student_Details"/>
       </property>
   </bean>
</beans>

Compile and run the program will get the below result:

Result:

Inside Student_Details  constructor
Inside setName
Inside Stud_Address