The Spring Framework provides powerful features for building flexible and modular applications. One such feature is the @Conditional
annotation, which allows you to conditionally enable or disable certain components based on specific conditions. In this tutorial, we’ll delve into the usage of @Conditional
with practical code examples to better understand its capabilities.
Prerequisites:
- Basic knowledge of the Spring Framework.
- A Java development environment set up with Spring dependencies.
Getting Started:
The @Conditional
annotation is used at the class level to conditionally enable or disable a component. It is often combined with other conditions to achieve more complex scenarios.
Basic Example:
Let’s start with a simple example where we conditionally enable a bean based on a system property.
In this example, MyBean
will be created only if the system property enableMyBean
is set to true
.
Using multiple conditions:
You can combine multiple conditions using the @ConditionalOn...
annotations provided by Spring Boot.
In this case, the MyFeature
bean will be created only if the property myapp.feature.enabled
is set to true
and the class com.example.SomeClass
is present in the classpath.
Custom Condition:
You can create custom conditions by implementing the Condition
interface. Let’s create a custom condition that checks the availability of a specific bean.
In this example, the MyConfiguration
class will be conditionally enabled only if the bean named requiredBean
is available.
Conclusion:
The @Conditional
annotation in Spring provides a powerful mechanism for creating flexible and adaptive configurations. By using conditions, you can control the instantiation of beans based on various factors, enhancing the modularity and configurability of your Spring applications.