FactoryBean

FactoryBean is an interface in Spring Framework that serves as a factory for creating bean instances. It allows you to define custom logic for creating and configuring objects that can be managed by the Spring container.

Here's a brief overview of FactoryBean:

1. Definition: FactoryBean is an interface with a single method getObject(), which is responsible for creating and returning an instance of the target object.

2. Customization: Implementing the FactoryBean interface allows you to define custom logic for creating and configuring bean instances. This can be useful when the creation logic of a bean is complex or requires additional customization.

3. Type Safety: The FactoryBean interface is parameterized with the type of object it produces. This provides type safety when using the factory bean to obtain instances of the target object.

4. Lifecycle Management: FactoryBean implementations can also implement other Spring lifecycle interfaces like InitializingBean and DisposableBean, allowing you to perform initialization and cleanup logic.

5. Example: Here's a simple example of a FactoryBean implementation:

import org.springframework.beans.factory.FactoryBean;

public class MyBeanFactory implements FactoryBean<MyBean> {

    @Override
    public MyBean getObject() throws Exception {
        // Custom logic to create and configure MyBean instance
        MyBean myBean = new MyBean();
        myBean.setProperty("value");
        return myBean;
    }

    @Override
    public Class<?> getObjectType() {
        return MyBean.class;
    }

    @Override
    public boolean isSingleton() {
        return true;
    }
}

In this example, MyBeanFactory implements the FactoryBean<MyBean> interface and provides custom logic in the getObject() method to create and configure a MyBean instance. The getObjectType() method returns the type of object produced by the factory, and the isSingleton() method indicates whether the factory produces singleton or prototype objects.

Overall, FactoryBean provides a flexible mechanism for creating and configuring bean instances in a Spring application context. It is commonly used when you need to customize the creation process of beans beyond what is possible with traditional bean definitions.