Import components such as ioc containers through @ import:

Three ways:

1. Add class name directly to @ import.

@Import(value = {Person.class, com.tuling.testimport.compent.Car.class})

2. @Import import implements the components of the ImportSeletor class, which can import multiple custom instances at once

@Import(value = {Person.class, TulingImportSelector.class})

3, @ Import import implements the class of importbeandefinitionregister, which can register multiple classes in the implementation class.

@Import(value = {Person.class, TulingBeanDefinitionRegister.class})

 

1. Add class name directly to @ import

Configuration class:

@Configuration
@Import(value = {Person.class, com.tuling.testimport.compent.Car.class})
public class MainConfig {
}

Execution class:

public class MainClass {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(MainConfig.class);
        for(String beanName:ctx.getBeanDefinitionNames()) {
            System.out.println("beanName: "+beanName);
        }
    }
}

Execution result:

2. ImportSelector :

Configuration class:

@Configuration
@Import(value = {Person.class, TulingImportSelector.class})
TulingBeanDefinitionRegister.class})
public class MainConfig {
}

Implement the ImportSelector interface

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

public class TulingImportSelector implements ImportSelector {
    @Override
    public String[] selectImports(AnnotationMetadata importingClassMetadata) {
        return new String[]{"com.tuling.testimport.compent.Dog", "com.tuling.testimport.compent.Car"};
    }
}

Main class:

public class MainClass {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(MainConfig.class);
        for(String beanName:ctx.getBeanDefinitionNames()) {
            System.out.println("beanName: "+beanName);
        }
    }
}

Execution result:

 

 

 

3. ImportBeanDefinitionRegistrar

Configuration class:

import com.tuling.testimport.compent.Person;
import com.tuling.testimport.importselect.TulingBeanDefinitionRegister;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;

/**
 * Created by smlz on 2019/5/20.
 */
@Configuration
@Import(value = {Person.class, TulingBeanDefinitionRegister.class})
public class MainConfig {
}

Implement importbeandefinitionregister:

import com.tuling.testimport.compent.Car;
import com.tuling.testimport.compent.Cat;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.RootBeanDefinition;
import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
import org.springframework.core.type.AnnotationMetadata;

public class TulingBeanDefinitionRegister implements ImportBeanDefinitionRegistrar {
    @Override
    public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
        RootBeanDefinition catDef = new RootBeanDefinition(Cat.class);
        RootBeanDefinition carDef = new RootBeanDefinition(Car.class);
        registry.registerBeanDefinition("cat",catDef);
        registry.registerBeanDefinition("car",carDef);;
    }
}

Main class:

public class MainClass {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(MainConfig.class);
        for(String beanName:ctx.getBeanDefinitionNames()) {
            System.out.println("beanName: "+beanName);
        }
        System.out.println(ctx.getBean("car"));
    }
}

Execution result: