Spring boot: ConditionalOnExpression with a nonEmpty property

if you want to conditionally load a bean on Spring boot, you can use the @Conditional classes. Click here for the spring boot reference, or a guide from Baeldung.

If we want to load a bean if a property is not empty, we can use ConditionalOnExpression with SpEl (Spring Expression language). If you have apache commons loaded (recommended), create this condition:

@Bean
@ConditionalOnExpression(
    "T(org.apache.commons.lang3.StringUtils).isNotEmpty('${my-prop:}')"
)
class YourClass() {
 ...
}

In case you want to reuse this condition in more than one place, you can create the annotation class

@Target({ ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@Documented
@ConditionalOnExpression(
    "T(org.apache.commons.lang3.StringUtils).isNotEmpty('${my-prop:}')"
)
public @interface ConditionalOnMyPropNotEmpty {
}

and then use it in your beans

@ConditionalOnMyPropNotEmpty
class YourClass1() {
 ...
}




@ConditionalOnMyPropNotEmpty
class YourClass2() {
 ...
}

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