java - 由于 JDK 代理而导致 UnsatisfiedDependencyException

Question

我尝试使用 Spring 提供的默认 aop 代理，但出现执行错误。

这是我的代码:运行测试示例的第一个类。

@EnableAspectJAutoProxy()
@ComponentScan(basePackageClasses = {MyDaoRepository.class, MyService.class,MyAdvices.class})
@Configuration
public class SpringAdvices {
   public static void main( String[] args ) {
        ApplicationContext ctx = new AnnotationConfigApplicationContext(SpringAdvices.class);
        service myService = ctx.getBean(MyService.class);
        Person p1 = (Person) ctx.getBean("person");
        myService.save(p1);

    }
     @Bean
     public Person person(){
            return Person.builder()
                    .name("Bagna")
                    .age(52)
                    .profession(null)
                    .dateOfBirth(LocalDate.of(1950,12,13))
                    .build();
        }

}

代表我建议的第二堂课:

@Aspect
@Component
public class MyAdvices {
    @Before("execution(boolean *.dao.save(..))")
    public void beforesavamethod(){
        System.out.println("beforesavamethod");
    }
    @After("execution(boolean *.dao.save(..))")
    public void aftersavamethod(){
        System.out.println("aftersavamethod");
    }
}

我的服务和存储库类:

@Service
public class MyService implements service {
    @Autowired
    MyDaoRepository myDaoRepository;

    @Override
    public boolean save( Person person ){
        return this.myDaoRepository.save(person);
    }
    @Override
    public boolean delete(Person person){
        return  this.myDaoRepository.delete(person);
    }
}

public interface service {
    public  boolean save( Person person );
    public  boolean delete( Person person );
}
@Repository
public class MyDaoRepository implements dao {
    List<Person> personList = new ArrayList<>();

    @Override
    public boolean save( Person person ){
        return this.personList.add(person);
    }

    @Override
    public boolean delete( Person person ){
        return  this.personList.remove(person);
    }
}
public interface dao {
    public boolean save( Person person );

    public boolean delete( Person person );
}

我遇到的异常(exception)是向服务对象注入(inject) dao 对象。

UnsatisfiedDependencyException: Error creating bean with name 'myService': Unsatisfied dependency expressed through field 'myDaoRepository'; nested exception is org.springframework.beans.factory.BeanNotOfRequiredTypeException: Bean named 'myDaoRepository' is expected to be of type 'aop.question_005.dao.MyDaoRepository' but was actually of type 'com.sun.proxy.$Proxy22'

我可以通过启用 GCLIB 机制来解决这个问题，但我想知道如何使用相同的 JDK 动态代理来解决这个问题？

Answer 1

代码中的问题是您使用类 MyDaoRepository 而不是 dao 接口(interface)。您可以将代理强制转换为接口(interface) dao，但不能将其强制转换为其实现。您需要修改服务代码才能使用接口(interface):

@Service
public class MyService implements service {
    @Autowired
    dao myDaoRepository;

    @Override
    public boolean save( Person person ){
        return this.myDaoRepository.save(person);
    }
    @Override
    public boolean delete(Person person){
        return  this.myDaoRepository.delete(person);
    }
}