springbean的八种加载方式汇总

@Service
public class BookServiceImpl implements BookService { }

public class AppImport {
    
public static void main(String[] args) {
    
AnnotationConfigApplicationContext ctx =
new AnnotationConfigApplicationContext(SpringConfig5.class);

ctx.register(Cat.class);

String[] names = ctx.getBeanDefinitionNames();

for (String name : names) {
System.out.println(name);
}
}
}

@Configuration
@ComponentScan("com.itheima")
public class SpringConfig {
@Bean
public DruidDataSource getDataSource(){
DruidDataSource ds = new DruidDataSource();
return ds; 
}
 }

@Configuration
@ComponentScan("com.itheima")
public class SpringConfig {

@Bean
public DruidDataSource getDataSource(){
DruidDataSource ds = new DruidDataSource();
return ds; } 
}

public class SpringConfig8 {

@Bean
public BookFactoryBean book(){
return new BookFactoryBean();
}

}

@Import(Dog.class)
public class SpringConfig5 { } 被导入的bean无需使用注解声明为bean
public class Dog { }

public class MyImportSelector implements ImportSelector {
public String[] selectImports(AnnotationMetadata metadata) {

boolean flag = metadata.hasAnnotation("org.springframework.context.annotation.Import");//判断SpringConfig5的元数据有哪些特征。有没有import注解


if(flag){
return new String[]{"com.itheima.domain.Dog"};
}
return new String[]{"com.itheima.domain.Cat"};
}

}
@Import(MyImportSelector.class)
public class SpringConfig5 { } 

public class MyRegistrar implements ImportBeanDefinitionRegistrar {
@Override    
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata,
BeanDefinitionRegistry registry) {

//AnnotationMetadata 同importselect方式判断元数据

BeanDefinition beanDefinition = BeanDefinitionBuilder
.rootBeanDefinition(BookServiceImpl2.class) .getBeanDefinition();
registry.registerBeanDefinition("bookService", beanDefinition);
}
//

}
@Import(MyRegistrar.class)
public class SpringConfig6 { } 

public class MyPostProcessor implements BeanDefinitionRegistryPostProcessor {

@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {
BeanDefinition beanDefinition = BeanDefinitionBuilder
.rootBeanDefinition(BookServiceImpl4.class) .getBeanDefinition();
registry.registerBeanDefinition("bookService", beanDefinition);
}

}
@Import({BookServiceImpl1.class, MyPostProcessor.class, MyRegistrar2.class, MyRegistrar.class})
public class SpringConfig8 {
}