What is the @Conditional annotation in Spring and what is it used for?

The @Conditional annotation in Spring is used for conditional creation of beans or configurations based on specified conditions. It allows including or excluding components from the application context depending on the environment, presence of classes, properties, and other factors.

For example, a bean can be created only if a certain class is present in the classpath or if a specific property is set.

Example usage:

@Configuration
@ConditionalOnProperty(name = "feature.enabled", havingValue = "true")
public class FeatureConfig {
    // the bean will be created only if feature.enabled=true in properties
}

@Conditional is a more general mechanism on which specialized annotations like @ConditionalOnProperty, @ConditionalOnClass, and others are based. Inside @Conditional, a class implementing the Condition interface is specified, where the logic for checking the condition is described.

This allows flexible management of application configuration and the creation of adaptive settings for different environments and scenarios.