如何找到带有自定义注释@Foo 的所有 bean?

问题描述

我有这个弹簧配置:

@Lazy
@Configuration
public class MyAppConfig {
    @Foo @Bean
    public IFooService service1() { return new SpecialFooServiceImpl(); }
}

如何获得所有用 @Foo 注释的 bean 的列表?

How can I get a list of all beans that are annotated with @Foo?

注意:@Foo 是我定义的自定义注解.它不是官方"Spring 注释之一.

Note: @Foo is a custom annotation defined by me. It's not one of the "official" Spring annotations.

按照 Avinash T. 的建议，我编写了这个测试用例:

Following the suggestions of Avinash T., I wrote this test case:

import static org.junit.Assert.*;
import java.lang.annotation.ElementType;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import java.lang.annotation.Retention;
import java.lang.reflect.Method;
import java.util.Map;
import org.junit.Test;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Lazy;

public class CustomAnnotationsTest {

    @Test
    public void testFindByAnnotation() throws Exception {

        AnnotationConfigApplicationContext appContext = new AnnotationConfigApplicationContext( CustomAnnotationsSpringCfg.class );

        Method m = CustomAnnotationsSpringCfg.class.getMethod( "a" );
        assertNotNull( m );
        assertNotNull( m.getAnnotation( Foo.class ) );

        BeanDefinition bdf = appContext.getBeanFactory().getBeanDefinition( "a" );
        // Is there a way to list all annotations of bdf?

        Map<String, Object> beans = appContext.getBeansWithAnnotation( Foo.class );
        assertEquals( "[a]", beans.keySet().toString() );
    }


    @Retention( RetentionPolicy.RUNTIME )
    @Target( ElementType.METHOD )
    public static @interface Foo {

    }

    public static class Named {
        private final String name;

        public Named( String name ) {
            this.name = name;
        }

        @Override
        public String toString() {
            return name;
        }
    }

    @Lazy
    @Configuration
    public static class CustomAnnotationsSpringCfg {

        @Foo @Bean public Named a() { return new Named( "a" ); }
             @Bean public Named b() { return new Named( "b" ); }
    }
}

但它失败了 org.junit.ComparisonFailure: expected:<[[a]]>但是是:.为什么?

but it fails with org.junit.ComparisonFailure: expected:<[[a]]> but was:<[[]]>. Why?

推荐答案

在几个 Spring 专家的帮助下，我找到了一个解决方案:BeanDefinition 的 source 属性code> 可以是 AnnotatedTypeMetadata.这个接口有一个方法 getAnnotationAttributes()，我可以用它来获取 bean 方法的注释:

With the help of a couple of Spring experts, I found a solution: The source property of a BeanDefinition can be AnnotatedTypeMetadata. This interface has a method getAnnotationAttributes() which I can use to get the annotations of a bean method:

public List<String> getBeansWithAnnotation( Class<? extends Annotation> type, Predicate<Map<String, Object>> attributeFilter ) {

    List<String> result = Lists.newArrayList();

    ConfigurableListableBeanFactory factory = applicationContext.getBeanFactory();
    for( String name : factory.getBeanDefinitionNames() ) {
        BeanDefinition bd = factory.getBeanDefinition( name );

        if( bd.getSource() instanceof AnnotatedTypeMetadata ) {
            AnnotatedTypeMetadata metadata = (AnnotatedTypeMetadata) bd.getSource();

            Map<String, Object> attributes = metadata.getAnnotationAttributes( type.getName() );
            if( null == attributes ) {
                continue;
            }

            if( attributeFilter.apply( attributes ) ) {
                result.add( name );
            }
        }
    }
    return result;
}

gist 包含辅助类和测试用例的完整代码

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