Spring中bean的几种注入方式

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声明式注入

@Configuration + @Bean

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@Configuration
public class QuickstartConfiguration {
    @Bean
    public Person person() {
        return new Person();
    }
}

@Component + @ComponentScan

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@Configuration
@ComponentScan("com.linkedbear.spring.annotation.c_scan")
public class ComponentScanConfiguration

@Import

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@Import({Boss.class, BartenderConfiguration.class})
public @interface EnableTavern

配置式注入

<bean>标签声明

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<bean id="person" class="com.linkedbear.spring.basic_dl.a_quickstart_byname.bean.Person"/>

编程式注入 BeanDefinition

ImportBeanDefinitionRegistrar

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public class WaiterRegistrar implements ImportBeanDefinitionRegistrar {
    
    @Override
    public void registerBeanDefinitions(AnnotationMetadata metadata, BeanDefinitionRegistry registry) {
        registry.registerBeanDefinition("waiter", new RootBeanDefinition(Waiter.class));
    }
}

手动构造 BeanDefinition 注入

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AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();

BeanDefinition personDefinition = BeanDefinitionBuilder.rootBeanDefinition(Person.class)
        .addPropertyValue("name", "zhangsan").getBeanDefinition();
ctx.registerBeanDefinition("person", personDefinition);

ctx.refresh();

借助 BeanDefinitionRegistryPostProcessor 注入

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public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
    registry.registerBeanDefinition("animalNameSetterPostProcessor", 
            new RootBeanDefinition(AnimalNameSetterPostProcessor.class));
}