Spring 框架: expected single matching bean but found 2

Question

这个父类(super class) DAO:

public class CrudDAO{

}

这个子类:

@Repository
public class JnsTimeDao extends CrudDAO {

}

@Repository
public class BatchDAO extends CrudDAO {
}

这个 super 服务等级

@Transactional(readOnly = true)
public abstract class CrudService<D extends CrudDAO> {

    @Autowired
    protected D dao;
}

启动错误:

org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.gp.dao.CrudDAO] is defined: expected single matching bean but found 2: batchDAO,jnsTimeDao

Answer 1

有 2 个 CrudDAO 类型的 bean .因此，Spring 将无法理解要注入(inject)哪个 bean。可以如下解决

@Repository("jnsTimeDao")
public class JnsTimeDao extends CrudDAO {

}

@Repository("batchDao")
public class BatchDAO extends CrudDAO {
}

注入(inject)时使用 @Qualifier

 @Transactional(readOnly = true)
    public abstract class CrudService<D extends CrudDAO> {

        @Autowired
        @Qualifier("batchDao")
        protected D dao;
    }