What is the difference between spring factory-method and factory-bean?

factory-method: represents the factory method that will be invoked to inject the bean.factory-bean: represents the reference of the bean by which factory method will be invoked. It is used if factory method is non-static.

Printable.java

package com.javatpoint;  public interface Printable {      void print();  }  

A.java

package com.javatpoint;  public class A implements Printable{      @Override      public void print() {          System.out.println("hello a");      }      } 

B.java

package com.javatpoint;  public class B implements Printable{      @Override      public void print() {          System.out.println("hello b");      }  }  

PrintableFactory.java

package com.javatpoint;  public class PrintableFactory {      //non-static factory method      public Printable getPrintable(){          return new A();//return any one instance, either A or B      }  }  

applicationContext.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"      xmlns:p="http://www.springframework.org/schema/p"      xsi:schemaLocation="http://www.springframework.org/schema/beans   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">  <bean id="pfactory" class="com.javatpoint.PrintableFactory"></bean>  <bean id="p" class="com.javatpoint.Printable" factory-method="getPrintable"   factory-bean="pfactory"></bean>  </beans>  

Notice that public Printable getPrintable() of PrintableFactory.java is a non-static method. Generally if we want access/call method or other resources of the a class we have to create it's instance. Similarly in that we created it bean. using bean's reference variable pfactory we are calling the factory method getPrintable.

It's basically the same difference between the Factory method and Factory design patterns, with a little note at the bottom. While one is a method used to obtain instances of a specific class, the other is a full fledged object responsible of creating objects, including all of the required logic to do so.

FactoryBean's interface documentation states:

Interface to be implemented by objects used within a BeanFactory which are themselves factories. If a bean implements this interface, it is used as a factory for an object to expose, not directly as a bean instance that will be exposed itself.

Also, this object is not used as a bean instance, but as an instance provider through its getObject method.

Update

Searching for uses of factory-method over a FactoryBean, it seems that it used quite oftenly with legacy singleton beans, to get the underlying instance, but this approach doesn't provide support for initialization methods, such as, for example, an init method that initializes a given set of properties.

In this case, you either have to invoke it yourself before using the class, define a wrapper that handles the initialization or make use of other mechanisms such as MethodInvokingFactoryBean.

Update 2

Strictly speaking, a FactoryBean is intended to manage a specific type. You'd have, in fact, an EggPlantFactory, not a VegetableFactory since the getObject method defined by the FactoryBean interface doesn't support parameters.

factory-method:
As everyone has already explained, factory-method is used to tell the spring to use the factory method to instantiate the object.

Note: static method is mandatory else throws an exception.

<bean id="serviceFactory" class="com.test.controller.ServiceFactory" factory-method="getServiceFacrotyWithStaticMethod"/>

factory-bean:
When there is no static method and still you want to create the object using non static method, here is the trick can be done using factory-bean:

<bean id="instanceWithOutStaticMethod" factory-bean="serviceFactory" factory-method="getInstanceWithOutStaticMethod" />

Note: no class attribute required in the above spring definition.

Class:

public class ServiceFactory {    public static ServiceFactory getServiceFacrotyWithStaticMethod(){        return new ServiceFactory();    }    public SdCard getInstanceWithOutStaticMethod(){        return new AdaptorSlot("laptop");    }}