Spring Framework - DeferredImportSelector Examples

package com.logicbig.example;

import org.springframework.context.annotation.DeferredImportSelector;
import org.springframework.core.type.AnnotationMetadata;

public class MyImportSelector implements DeferredImportSelector {

    @Override
    public String[] selectImports(AnnotationMetadata importingClassMetadata) {
        String prop = System.getProperty("myProp");
        if ("someValue".equals(prop)) {
            return new String[]{MyConfig1.class.getName()};
        } else {
            return new String[]{MyConfig2.class.getName()};
        }
    }
}

package com.logicbig.example;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MyConfig1 {
    @Bean
    AppBean appBean() {
        return new AppBean("from config 1");
    }
}

package com.logicbig.example;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MyConfig2 {
    @Bean
    AppBean appBean() {
        return new AppBean("from config 2");
    }
}

package com.logicbig.example;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;

@Configuration
@Import(MyImportSelector.class)
public class MainConfig {

    @Bean
    ClientBean clientBean() {
        return new ClientBean();
    }

    @Bean
    AppBean appBean() {
        return new AppBean("from main config");
    }

}

package com.logicbig.example;

public class AppBean {
    private String message;

    public AppBean(String message) {
        this.message = message;
    }

    public String getMessage() {
        return message;
    }
}

package com.logicbig.example;

import org.springframework.beans.factory.annotation.Autowired;

public class ClientBean {
    @Autowired
    private AppBean appBean;

    public void doSomething() {
        System.out.println(appBean.getMessage());
    }

}

package com.logicbig.example;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class DeferredImportSelectorExample {

    public static void main(String[] args) {
        System.setProperty("myProp", "someValue");

        ApplicationContext context =
                new AnnotationConfigApplicationContext(
                        MainConfig.class);
        ClientBean bean = context.getBean(ClientBean.class);
        bean.doSomething();
    }

}