Quick to the point introduction to Spring Framework

A definition of bean may contain the information of configuration, including values of property, constructor arguments, and also container information of specific like method of initialization etc.

A definition of Spring Bean inheritance concept is same as Java. A definition of child bean inherits data configuration from a base definition and the definition of child can add new values or override values if needed. Here a definition of base/parent bean is like template where child beans can inherit necessary configuration.

Example:

Java class: Home_Address

package pack1;  
  
public class Home_Address {  
private String Address1;  
  
public String setAddress1(String Address) {  
    this.Address1 = Address; 
  }  
public void getAddress1(){
      System.out.println("Home Address1 : " + Address1);
   }
}  

Java class: Office_Address

package pack1;  

public class Office_Address {  
private String Address1;
private String Address2;  
  
public String setAddress1(String Address) {  
    this.Address1 = Address; 
  }  
public String setAddress2(String Address) {  
    this.Address2 = Address; 
  }  
public void getAddress1(){
      System.out.println("Office Address1 : " + Address1);
   }
public void getAddress2(){
      System.out.println("Office Address2 : " + Address2);
   }
}  

And our Test class: 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("SingleBeans.xml ");

    Home_Address  home =( Home_Address)cont.getBean("Home_Address");  
    home.getAddress1();
    
Office_Address office =( Office_Address )cont.getBean("Office_Address");  
    office.getAddress1();
    office.getAddress2();
      }  
}  

The configuration file is SingleBeans.xml:

Here we defined "Home_Address" bean which has one property Address1. Next "Office_Address" bean is defined as a child of "Home_Address" bean by using parent attribute. The child bean overrides Address1 property and added new Address2 property.

<?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="home" class="pack1.Home_Address">
       <property name="Address1" value="National Blvd"/>
  </bean>

  <bean id="office" class="pack1.Office_Address"
       parent="home">
       <property name="Address2" value="Motor Ave"/>
   </bean>
  </beans>  

Here, we did not pass message2 while creating "office" bean, but it got passed because of Inheritance. 

Compile and run the program will get the below result:

Result:

Home Address1 : National Blvd
Office Address1 : National Blvd
Office Address1 : Motor Ave

Bean Definition Template:

a Bean definition template can create by user where it can be used by bean child definitions without easily. For defining a Template of Bean Definition, we should not give class attribute and should give abstract attribute value as true:

<?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="homeTemplate" abstract="true">
<property name="Address1" value="National Blvd"/>
  </bean>

  <bean id="office" class="pack1.Office_Address"
       parent="homeTemplate">
       <property name="Address2" value="Motor Ave"/>
   </bean>
  </beans>  

Here the parent bean is marked as abstract hence it cannot be instantiated on its own because it is incomplete where abstract like this is usable only as a pure template definition of bean that serves as a definition of parent for definitions of child.