@ImportResource

What

@ImportResource用于声明导入一个或多个BeanDefinition定义的资源。

Definition

package org.springframework.context.annotation;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
public @interface ImportResource {

    @AliasFor("locations")
    String[] value() default {};

    @AliasFor("value")
    String[] locations() default {};

    Class<? extends BeanDefinitionReader> reader() default BeanDefinitionReader.class;

}
属性 类型 说明 默认值
value String[] 资源路径 {}
locations String[] 资源路径 {}
reader Class BeanDefinitionReader BeanDefinitionReader.class

How

在ConfigurationClassParser的doProcessConfigurationClass()方法中，有如下的一段代码：

package org.springframework.context.annotation;

class ConfigurationClassParser {

    protected final SourceClass doProcessConfigurationClass(
        ConfigurationClass configClass, SourceClass sourceClass, Predicate<String> filter)
        throws IOException {
        ...
        // Process any @ImportResource annotations
        AnnotationAttributes importResource =
            AnnotationConfigUtils.attributesFor(sourceClass.getMetadata(), ImportResource.class);
        if (importResource != null) {
            String[] resources = importResource.getStringArray("locations");
            Class<? extends BeanDefinitionReader> readerClass = importResource.getClass("reader");
            for (String resource : resources) {
                String resolvedResource = this.environment.resolveRequiredPlaceholders(resource);
                configClass.addImportedResource(resolvedResource, readerClass);
            }
        }
        ...
        return null;
    }

}

该代码片段实现将类上的@ImportResource注解声明的locations和reader存储到ConfigurationClass类的importedResources属性上。