检索 ByteBuddy 生成的 Spring Bean 时出现问题

Question

我正在制作自己的 ORM，现在我想消除创建存储库 classes 的需要。他们目前看起来像这样：

@Repository
public class CustomerDao extends AbstractDao<Customer, Long>
{

}

在不深入我的 ORM 内部工作的情况下，AbstractDao class 使用一个 bean，它是一个包含实体 class 作为键和 dao class 的映射作为一个值。在不混合 ByteBuddy 的情况下，该 bean 的声明如下所示：

@Bean
public Map<Class<?>, AbstractDao<?, ?>> daoMap()
{
    context.getBeansWithAnnotation(Repository.class).forEach((s, c) ->
    {
        if (c instanceof AbstractDao<?, ?>) map.put(ClassUtils.getSuperClassTypeArgument(c.getClass(), 0), (AbstractDao<?, ?>) c);
    });

    return map;
}

同样，这很好用，但是必须创建这些空的 classes 非常烦人。我正在尝试使用 Reflections 和 ByteBuddy 库在运行时生成这些 classes 并将它们作为存储库 bean 动态注入到 Spring 上下文中。这是我修改后的方法：

@Bean
public Map<Class<?>, AbstractDao<?, ?>> daoMap() throws InstantiationException, IllegalAccessException, IllegalArgumentException, 
    InvocationTargetException, ConstructorMissingException, AnnotationMissingException, NoSuchMethodException, SecurityException
{
    var map = new HashMap<Class<?>, AbstractDao<?, ?>>();

    var byteBuddy = new ByteBuddy();

    for (var entityClass : new Reflections("com.somepackage.entity").getSubTypesOf(Entity.class))
    {
        var daoClass = byteBuddy
            .subclass(TypeDescription.Generic.Builder.parameterizedType(AbstractDao.class, entityClass, 
                ReflectionUtils.getIdField(entityClass).getType()).build())
            .annotateType(AnnotationDescription.Builder.ofType(Repository.class).build())
            .make();

        var clazz = daoClass.load(getClass().getClassLoader()).getLoaded();

        ((GenericApplicationContext) context).registerBean(clazz, clazz.getConstructor().newInstance());
    }

    context.getBeansWithAnnotation(Repository.class).forEach((s, c) ->
    {
        if (c instanceof AbstractDao<?, ?>) map.put(ClassUtils.getSuperClassTypeArgument(c.getClass(), 0), (AbstractDao<?, ?>) c);
    });

    return map;
}

创建 classes 并将它们作为 bean 注入的循环似乎工作正常。它不会抛出异常并影响正确的 classes。但是，我在 getBeansWithAnnotation 行遇到异常：

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.mdenis.carbon.carbon_orm.dao.AbstractDao$ByteBuddy$jzMtXq5b': Could not resolve matching constructor (hint: specify index/type/name arguments for simple parameters to avoid type ambiguities)
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:278) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1358) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1204) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean[=14=](AbstractBeanFactory.java:323) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansWithAnnotation(DefaultListableBeanFactory.java:672) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.getBeansWithAnnotation(AbstractApplicationContext.java:1264) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at com.mdenis.carbon.carbon_orm.config.ORMConfig.daoMap(ORMConfig.java:55) ~[classes/:na]
at com.mdenis.carbon.carbon_orm.config.ORMConfig$$EnhancerBySpringCGLIB$fd9cb34.CGLIB$daoMap(<generated>) ~[classes/:na]
at com.mdenis.carbon.carbon_orm.config.ORMConfig$$EnhancerBySpringCGLIB$fd9cb34$$FastClassBySpringCGLIB$$a25eec90.invoke(<generated>) ~[classes/:na]
at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244) ~[spring-core-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:331) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE]
at com.mdenis.carbon.carbon_orm.config.ORMConfig$$EnhancerBySpringCGLIB$fd9cb34.daoMap(<generated>) ~[classes/:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE]
... 85 common frames omitted

这似乎与 Spring 未能自动装配构造函数有关，即使它在技术上不必这样做。知道如何解决这个问题吗？

Answer 1

您的问题与byte-buddy无关。如果您尝试注册预先存在的 class.

，也会出现该错误

您需要在上下文启动的早期阶段注册新 bean。一种方法是使用 BeanFactoryPostProcessor。将您的地图创建分成两个部分。 class代的那个变成了BeanFactoryPostProcessor代。您可以在 @Bean 工厂方法

中保留 Map 代的那个

例如：

@Configuration
public class RepositoryConfigurationBean implements BeanFactoryPostProcessor {

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory configurableListableBeanFactory) throws BeansException {
        try {
            // Replace X1.class with the one from bytebuddy
            // The name should be unique
            configurableListableBeanFactory.registerSingleton("abc", X1.class.getConstructor().newInstance());
        } catch (InstantiationException | IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
            e.printStackTrace();
        }
   }

检索 ByteBuddy 生成的 Spring Bean 时出现问题

Issue retrieving ByteBuddy-generated Spring Bean

java

reflection

spring

spring-bean

byte-buddy