Springbootで@import注記でJavaクラスをインポートしてbeanと宣言する3つの方法

一般Javaクラスへの直接インポート:

	public class Car1 {
	    public void say(){
	        System.out.println("i am car1");
	    }
	}
	---
	@Configuration
	@Import(value = {Car1.class})
	public class AutoConfig {
	}
	---
	AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(AutoConfig.class);
    Car1 car1 = context.getBean(Car1.class);
    car1.say();

は、ImportSelectorインターフェースと組み合わせて使用する:このインターフェースを実装し、その中のselectImportsメソッドを書き換え、インポートする必要があるJavaクラスの全限定名からなる文字列配列

を返す.

	public class Car2 {
	    public void say(){
	        System.out.println("i am car2");
	    }
	}
	---
	public class CustomImportSelector implements ImportSelector {
	    @Override
	    public String[] selectImports(AnnotationMetadata annotationMetadata) {
	        String[] arr = new String[1];
	        arr[0] = "com.blade.demo.autoConfigure.Car2";
	        return arr;
	    }
	}
	---
	@Configuration
	@Import(value = {Car1.class, CustomImportSelector.class})
	public class AutoConfig {
	}
	---
	public class Test {
	    public static void main(String[] args) {
	        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(AutoConfig.class);
	        Car2 car2 = context.getBean(Car2.class);
	        car2.say();
	    }
	}

配合ImportBeanDefinitionRegistrar使用

	public class Car3 {
	    public void say(){
	        System.out.println("i am car3");
	    }
	}
	---
	public class CustomImportBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar{
	    @Override
	    public void registerBeanDefinitions(AnnotationMetadata annotationMetadata, BeanDefinitionRegistry beanDefinitionRegistry) {
	        RootBeanDefinition beanDefinition = new RootBeanDefinition(Car3.class);
	        beanDefinitionRegistry.registerBeanDefinition("car3",beanDefinition);
	    }
	}
	---
	@Configuration
	@Import(value = {Car1.class, CustomImportSelector.class, CustomImportBeanDefinitionRegistrar.class})
	public class AutoConfig {
	}
	---
	public class Test {
	    public static void main(String[] args) {
	        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(AutoConfig.class)；
	        Car3 car3 = context.getBean(Car3.class);
	        car3.say();
	    }
	}