what are conditional annotations in Spring Boot Application?

Conditional annotations in Spring Boot allow us to conditionally apply certain configurations or beans based on the evaluation of specified conditions at runtime. These annotations help in creating flexible and customizable application setups.

Here's how conditional annotations work and their use in a Spring Boot application:

• @ConditionalOnProperty: This annotation allows us to conditionally enable a bean or configuration based on the value of a specified property in the application's configuration files.
• @ConditionalOnClass: It enables a bean or configuration if specified classes are present in the classpath.
• @ConditionalOnMissingBean: This annotation allows us to define a bean only if another bean of the same type is not already registered in the application context.
• @ConditionalOnExpression: It enables a bean or configuration based on the evaluation of a SpEL expression.
• @ConditionalOnWebApplication: It enables a bean or configuration if the application is running in a web environment.
• @Conditional: This annotation provides a general-purpose mechanism to define custom conditions for bean registration.

Example:

Suppose we want to configure a bean only if a specific property is present in our application's configuration file. We can use @ConditionalOnProperty for this purpose:

@Configuration
public class MyConfiguration {

    @Bean
    @ConditionalOnProperty(name = "myapp.feature.enabled", havingValue = "true")
    public MyBean myBean() {
        return new MyBean();
    }
}

In this example, the MyBean bean will only be registered if the property myapp.feature.enabled is set to true in the application's properties file. Otherwise, it will not be created.

Conditional annotations provide a powerful mechanism to customize the behavior of our Spring Boot application based on various conditions, making our application more adaptable and efficient.