Spring Inner bean example - KK JavaTutorials

In this post, We will learn about the Spring Inner bean example using a Demo Project.

In the Spring framework, whenever a bean is used for only one particular property, it’s advised to declare it as an inner bean. Usually, the Spring inner bean is supported by both setter injection ‘property‘ and constructor injection ‘constructor-arg‘. Like Inner classes are the classes that are defined inside the scope of another class. Similarly, inner beans are the beans that are defined in the scope of another bean.

Injecting Inner Beans

<bean id="outerBean" class="com.kkjavatutorials.OuterBean">
      <property name="innerBean">
           <bean  class="com.kkjavatutorials.InnerBean"/>
      </property>
</bean>

</property>

</bean>

An inner bean usually does not require a defined id or name; if specified, the container does not use such a value as an identifier. The second key point is that Inner beans are always anonymous and they are always created within the scope of outer bean. It is not possible at all to inject inner beans into collaborating beans other than into the enclosing bean or to access them independently.

Now Let’s try to understand the Spring Inner bean using the below demo Project.

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.kkhindigyan.org</groupId>
  <artifactId>SpringInnerBeanExample</artifactId>
  <version>0.0.1-SNAPSHOT</version>
   <properties>
		<org.springframework.version>5.2.13.RELEASE</org.springframework.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-context</artifactId>
			<version>${org.springframework.version}</version>
		</dependency>
	</dependencies>
</project>

<groupId>com.kkhindigyan.org</groupId>

<artifactId>SpringInnerBeanExample</artifactId>

<version>0.0.1-SNAPSHOT</version>

<org.springframework.version>5.2.13.RELEASE</org.springframework.version>

</properties>

<groupId>org.springframework</groupId>

<artifactId>spring-context</artifactId>

<version>${org.springframework.version}</version>

</dependency>

</dependencies>

</project>

PaymentGateway.java

package com.kkhindigyan.model;

public class PaymentGateway {
	
	private String paymentGatewayId;
	private Order order;
	
	public PaymentGateway(String paymentGatewayId, Order order) {
		super();
		this.paymentGatewayId = paymentGatewayId;
		this.order = order;
	}
	
	public Order getOrder() {
		return order;
	}
	
	public String getPaymentGatewayId() {
		return paymentGatewayId;
	}
	
	/*public String getPaymentGatewayId() {
		return paymentGatewayId;
	}
	public void setPaymentGatewayId(String paymentGatewayId) {
		this.paymentGatewayId = paymentGatewayId;
	}
	public Order getOrder() {
		return order;
	}
	public void setOrder(Order order) {
		this.order = order;
	}*/
}

package com.kkhindigyan.model;

public class PaymentGateway {

private String paymentGatewayId;

private Order order;

public PaymentGateway(String paymentGatewayId, Order order) {

super();

this.paymentGatewayId = paymentGatewayId;

this.order = order;

}

public Order getOrder() {

return order;

}

public String getPaymentGatewayId() {

return paymentGatewayId;

}

/*public String getPaymentGatewayId() {

return paymentGatewayId;

}

public void setPaymentGatewayId(String paymentGatewayId) {

this.paymentGatewayId = paymentGatewayId;

}

public Order getOrder() {

return order;

}

public void setOrder(Order order) {

this.order = order;

}*/

}

Order.java

package com.kkhindigyan.model;

public class Order {

	private String itemName;
    private Double itemPrice;
    private String address;
    
	public String getItemName() {
		return itemName;
	}
	public void setItemName(String itemName) {
		this.itemName = itemName;
	}
	public Double getItemPrice() {
		return itemPrice;
	}
	public void setItemPrice(Double itemPrice) {
		this.itemPrice = itemPrice;
	}
	public String getAddress() {
		return address;
	}
	public void setAddress(String address) {
		this.address = address;
	}
	
	@Override
	public String toString() {
		return "Order [itemName=" + itemName + ", itemPrice=" + itemPrice + ", address=" + address + "]";
	}
}

package com.kkhindigyan.model;

public class Order {

private String itemName;

private Double itemPrice;

private String address;

public String getItemName() {

return itemName;

}

public void setItemName(String itemName) {

this.itemName = itemName;

}

public Double getItemPrice() {

return itemPrice;

}

public void setItemPrice(Double itemPrice) {

this.itemPrice = itemPrice;

}

public String getAddress() {

return address;

}

public void setAddress(String address) {

this.address = address;

}

@Override

public String toString() {

return "Order [itemName=" + itemName + ", itemPrice=" + itemPrice + ", address=" + address + "]";

}

applicationContext.xml

Here com.kkhindigyan.model.Order is configured as an inner bean.

<?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
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd">

	<bean id="paymentGateway"
		class="com.kkhindigyan.model.PaymentGateway">
		<constructor-arg name="paymentGatewayId"
			value="Google Pay"></constructor-arg>
		<constructor-arg name="order">
			<bean class="com.kkhindigyan.model.Order">
				<property name="itemName" value="iphone 11"></property>
				<property name="itemPrice" value="80000.00"></property>
				<property name="address" value="MG Road,Mumbai"></property>
			</bean>
		</constructor-arg>
	</bean>

</beans>

<?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

https://www.springframework.org/schema/beans/spring-beans.xsd

http://www.springframework.org/schema/context

https://www.springframework.org/schema/context/spring-context.xsd">

<bean id="paymentGateway"

class="com.kkhindigyan.model.PaymentGateway">

<constructor-arg name="paymentGatewayId"

value="Google Pay"></constructor-arg>

<constructor-arg name="order">

</bean>

</constructor-arg>

</bean>

</beans>

ClientTest.java

package com.kkhindigyan.org;

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

import com.kkhindigyan.model.PaymentGateway;

public class ClientTest {

	public static void main(String[] args) {
		
		AbstractApplicationContext applicationContext = null;
		
		try {
			
			//Creating Instance of ApplicationContext Spring Container
			applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
			PaymentGateway paymentGateway = applicationContext.getBean(PaymentGateway.class);
			System.out.println(paymentGateway.getPaymentGatewayId());
			System.out.println(paymentGateway.getOrder());
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			if (applicationContext != null)
				applicationContext.close();
		}
	}
}

package com.kkhindigyan.org;

import org.springframework.context.support.AbstractApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.kkhindigyan.model.PaymentGateway;

public class ClientTest {

public static void main(String[] args) {

AbstractApplicationContext applicationContext = null;

try {

//Creating Instance of ApplicationContext Spring Container

applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");

PaymentGateway paymentGateway = applicationContext.getBean(PaymentGateway.class);

System.out.println(paymentGateway.getPaymentGatewayId());

System.out.println(paymentGateway.getOrder());

} catch (Exception e) {

e.printStackTrace();

}finally {

if (applicationContext != null)

applicationContext.close();

}

If you run ClientTest.java as Java Application then it will give the below output:

Google Pay
Order [itemName=iphone 11, itemPrice=80000.0, address=MG Road,Mumbai]

That’s all about Spring Inner bean example

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