Using @Conditional with @Configuration in Spring allows us to group @Bean objects loaded on a specific condition without resorting to using @Profile and too many @Bean/@Conditional .
Requirements We used the following items for this post.
Spring Boot 2.0.4.RELEASE JDK 8 IntelliJ IDEA Grouping Beans into Two in Spring 1. All-English Configuration The @Configuration class contains all beans that give out String values in English. For example, consider the following codes.
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package com . turreta . conditionalconfiguration . conditionalconfiguration ;
import com . turreta . conditionalconfiguration . conditionalconfiguration . condition . EnglishLanguageCondition ;
import com . turreta . conditionalconfiguration . conditionalconfiguration . credits . CreditsEnglish ;
import com . turreta . conditionalconfiguration . conditionalconfiguration . helloworld . HelloWorldEnglish ;
import org . springframework . context . annotation . Bean ;
import org . springframework . context . annotation . Conditional ;
import org . springframework . context . annotation . Configuration ;
@Configuration
@Conditional ( EnglishLanguageCondition . class )
public class AllEnglishConfiguration
{
@Bean
public CreditsEnglish creditsEnglish ( )
{
return new CreditsEnglish ( ) ;
}
@Bean
public HelloWorldEnglish helloWorldEnglish ( )
{
return new HelloWorldEnglish ( ) ;
}
}
The Condition implementation for this is as follows:
package com . turreta . conditionalconfiguration . conditionalconfiguration . condition ;
import org . springframework . context . annotation . Condition ;
import org . springframework . context . annotation . ConditionContext ;
import org . springframework . core . type . AnnotatedTypeMetadata ;
public class EnglishLanguageCondition implements Condition
{
@Override
public boolean matches ( ConditionContext conditionContext , AnnotatedTypeMetadata annotatedTypeMetadata )
{
// Don't check for actual value
String lang = conditionContext . getEnvironment ( ) . getProperty ( "english" ) ;
return lang != null ;
}
}
2. All-German Configuration This @Configuration class contains all beans that give out String values in the German language. Consider the following codes.
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package com . turreta . conditionalconfiguration . conditionalconfiguration ;
import com . turreta . conditionalconfiguration . conditionalconfiguration . condition . GermanLanguageCondition ;
import com . turreta . conditionalconfiguration . conditionalconfiguration . credits . CreditsGerman ;
import com . turreta . conditionalconfiguration . conditionalconfiguration . helloworld . HelloWorldGerman ;
import org . springframework . context . annotation . Bean ;
import org . springframework . context . annotation . Conditional ;
import org . springframework . context . annotation . Configuration ;
@Configuration
@Conditional ( GermanLanguageCondition . class )
public class AllGermanConfiguration
{
@Bean
public CreditsGerman creditsGerman ( )
{
return new CreditsGerman ( ) ;
}
@Bean
public HelloWorldGerman helloWorldGerman ( )
{
return new HelloWorldGerman ( ) ;
}
}
The Condition implementation for this is as follows:
package com . turreta . conditionalconfiguration . conditionalconfiguration . condition ;
import org . springframework . context . annotation . Condition ;
import org . springframework . context . annotation . ConditionContext ;
import org . springframework . core . type . AnnotatedTypeMetadata ;
public class GermanLanguageCondition implements Condition
{
@Override
public boolean matches ( ConditionContext conditionContext , AnnotatedTypeMetadata annotatedTypeMetadata )
{
// Don't check for actual value
String lang = conditionContext . getEnvironment ( ) . getProperty ( "german" ) ;
return lang != null ;
}
}
Test @Conditional and @Configuration in Spring To toggle between languages, we explicitly set either one of the system properties – “English” or “German” – and run within the IDE.
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package com . turreta . conditionalconfiguration . conditionalconfiguration ;
import org . springframework . boot . SpringApplication ;
import org . springframework . boot . autoconfigure . SpringBootApplication ;
import org . springframework . context . ConfigurableApplicationContext ;
@SpringBootApplication
public class ConditionalconfigurationApplication
{
public static void main ( String [ ] args )
{
System . setProperty ( "german" , "any value" ) ;
//System.setProperty("english", "any value");
final ConfigurableApplicationContext context = SpringApplication
. run ( ConditionalconfigurationApplication . class , args ) ;
System . out . println ( context . getBean ( HelloWorld . class ) . getGreeting ( ) ) ;
System . out . println ( context . getBean ( Credits . class ) . getCredits ( ) ) ;
}
}
Then, we can test our codes by switching between languages using a property. For example, when we want to display a message in German, we could use the “German” system property, which is equivalent to
- Dgerman = "any value"
. . .
System . setProperty ( "german" , "any value" ) ;
. . .
Meanwhile, when we want to display a message in English, we use the “English” system property. Also, this is equivalent to
- Denglish = "any value"
System . setProperty ( "english" , "any value" ) ;
Download Spring @Conditional and @Configuration Sample Codes For more information, please download the codes from this GitHub repository .
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