Spring BeanFactory Container


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This is the simplest container providing the basic support for DI and defined by the org.springframework.beans.factory.BeanFactory interface. The BeanFactory and related interfaces, such as BeanFactoryAware, InitializingBean, DisposableBean, are still present in Spring for the purpose of backward compatibility with a large number of third-party frameworks that integrate with Spring.

There are a number of implementations of the BeanFactory interface that are come straight out-of-the-box with Spring. The most commonly used BeanFactory implementation is the XmlBeanFactory class. This container reads the configuration metadata from an XML file and uses it to create a fully configured system or application.

The BeanFactory is usually preferred where the resources are limited like mobile devices or applet-based applications. Thus, use an ApplicationContext unless you have a good reason for not doing so.

Example

Let us take a look at a working Eclipse IDE in place and take the following steps to create a Spring application −

Steps Description
1 Create a project with a name SpringExample and create a packagecom.tutorialspoint under the src folder in the created project.
2 Add the required Spring libraries using Add External JARs option as explained in the Spring Hello World Example chapter.
3 Create Java classes HelloWorld and MainApp under the com.tutorialspointpackage.
4 Create Beans configuration file Beans.xml under the src folder.
5 The final step is to create the content of all the Java files and Bean Configuration file. Finally, run the application as explained below.

Here is the content of HelloWorld.java file −

package com.tutorialspoint;  

public class HelloWorld { 
   private String message;  
   
   public void setMessage(String message){ 
      this.message  = message; 
   }  
   public void getMessage(){ 
      System.out.println("Your Message : " + message); 
   } 
}

Following is the content of the second file MainApp.java

package com.tutorialspoint;  

import org.springframework.beans.factory.InitializingBean; 
import org.springframework.beans.factory.xml.XmlBeanFactory; 
import org.springframework.core.io.ClassPathResource;  

public class MainApp { 
   public static void main(String[] args) { 
      XmlBeanFactory factory = new XmlBeanFactory (new ClassPathResource("Beans.xml")); 
      HelloWorld obj = (HelloWorld) factory.getBean("helloWorld");    
      obj.getMessage();    
   }
}   

Following two important points should be noted about the main program −

  • The first step is to create a factory object where we used the framework APIXmlBeanFactory() to create the factory bean andClassPathResource() API to load the bean configuration file available in CLASSPATH. The XmlBeanFactory() API takes care of creating and initializing all the objects, i.e. beans mentioned in the configuration file.

  • The second step is used to get the required bean using getBean() method of the created bean factory object. This method uses bean ID to return a generic object, which finally can be casted to the actual object. Once you have the object, you can use this object to call any class method.

Following is the content of the bean configuration file 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 = "helloWorld" class = "com.tutorialspoint.HelloWorld">
      <property name = "message" value = "Hello World!"/>
   </bean>

</beans>

Once you are done with creating the source and the bean configuration files, let us run the application. If everything is fine with your application, it will print the following message −

Your Message : Hello World!

spring_ioc_containers.htm

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