Conditional Properties in Spring Boot

In Spring Boot, conditional properties allow developers to configure application properties and enable/disable specific features based on various conditions at runtime. In this article, we’ll dive into conditional properties in Spring Boot and demonstrate their usage with some examples.

ConditionalOnProperty
The ConditionalOnProperty annotation is commonly used to conditionally enable or disable a specific bean or configuration based on the value of a property. Let’s consider an example where we have a configuration bean that should only be created if a specific property is set to true.

@Configuration
@ConditionalOnProperty(name = ["myapp.feature.enabled"], havingValue = "true")
class FeatureConfiguration {
    // Bean configuration code here
}

In this example, the FeatureConfiguration bean will only be created if the property myapp.feature.enabled is set to true.

ConditionalOnExpression
The ConditionalOnExpression annotation provides more flexibility by allowing developers to specify custom SpEL (Spring Expression Language) expressions as conditions for enabling or disabling a bean or configuration. Let’s say we want to create a bean only if multiple properties match certain conditions.

@Configuration
@ConditionalOnExpression("\${myapp.feature.enabled} && \${myapp.environment} == 'production'")
class FeatureConfiguration {
    // Bean configuration code here
}

In this example, the FeatureConfiguration bean will only be created if the property myapp.feature.enabled is true and the property myapp.environment is set to 'production'.

ConditionalOnClass
The ConditionalOnClass annotation allows creating beans or configurations only if a specific class is present in the classpath. This condition is useful when we want to configure certain features based on the availability of a particular dependency.

@Configuration
@ConditionalOnClass(name = ["org.springframework.security.core.Authentication"])
class SecurityConfiguration {
    // Bean configuration code here
}

In this example, the SecurityConfiguration bean will only be created if the class org.springframework.security.core.Authentication is present in the classpath.

ConditionalOnBean
The ConditionalOnBean annotation enables the creation of a bean or configuration only if a specific bean is present in the application context. This condition is helpful when we have dependencies between beans and want to ensure that certain configurations are applied only if the required beans are available.

@Configuration
@ConditionalOnBean(name = ["myBean"])
class MyConfiguration {
    // Bean configuration code here
}

In this case, the MyConfiguration bean will only be created if the bean with the name myBean is present in the application context.

Conditional properties in Spring Boot provide a powerful mechanism for configuring applications based on different conditions. By leveraging these annotations, developers can control the creation and behavior of beans and configurations dynamically. Whether it’s enabling features, checking property values, or validating class dependencies, conditional properties offer flexibility and adaptability.

Remember, these are just a few examples of the conditional property annotations available in Spring Boot. Depending on your requirements, you can explore other annotations

About the Author

You may also like these