Java Hibernate：如何映射带有多态性的@ManyToOne（@ManyToAny）

假设我至少有两个实体

@Entity
public class Process {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(unique = true)
    private String name;

    @ManyToAny(
            metaColumn = @Column(name = "node_type"),
            fetch = FetchType.LAZY
    )
    @AnyMetaDef(
            idType = "long", metaType = "string",
            metaValues = {
                    @MetaValue(targetEntity = Milestone.class, value = MILESTONE_DISC),
                    @MetaValue(targetEntity = Phase.class, value = PHASE_DISC)
            }
    )
    @Cascade({org.hibernate.annotations.CascadeType.ALL})
    @JoinTable(
            name = "process_nodes",
            joinColumns = @JoinColumn(name = "process_id", nullable = false),
            inverseJoinColumns = @JoinColumn(name = "node_id", nullable = false)
    )
    private Collection<ProcessNode> nodes = new ArrayList<>();

    ...
}

我可以从里程碑访问流程，并且流程不会保存在里程碑表中

有没有更干净的方法来实现这一点？

---

第二次编辑

更多详情：

ProcessNode是另两个实体从中继承的接口。使用hibernate annotations@ManyToAny，我将其映射到以下结构中：

---

无论如何，这里有一个使用类的工作解决方案，它们按预期工作

        @SpringBootApplication
    public class AccessingDataJpaApplication {
        
        public static void main(String[] args) {
            ConfigurableApplicationContext context 
                    = SpringApplication.run(AccessingDataJpaApplication.class);
            ProcessService processService 
                    = context.getBean(ProcessService.class);
    
            Process process = new Process();
            process.setName("process-1");
    
            Milestone milestoneOne = new Milestone();
            milestoneOne.setProcess(process);
            milestoneOne.setName("milestone-1");
    
            Milestone milestoneTwo = new Milestone();
            milestoneTwo.setProcess(process);
            milestoneTwo.setName("milestone-2");
    
            process.setNodes(Arrays.asList(milestoneOne, milestoneTwo));
            processService.save(process);
            processService.findAll();
        }
    }

---

谢谢你的回答。你看过我的编辑吗？我添加了@Transient注释，因为我的问题是流程被插入到里程碑表中。当您说流程被插入到里程碑表中时，您是指流程_id吗？否，id和名称属于里程碑，流程列引用流程实体。但我现在明白你的问题了。所以，您的问题是，里程碑表应该只有两列id和name，而不是process列。晚饭后我会很快回来找你。它应该可以通过映射或指示它已经在联接表中来实现。不幸的是，它不起作用。进程Id列在联接表和里程碑表中是重复的，如果您使其成为临时的，则没有意义，因为它不会填充引用。这不是一个大问题，因为一个列重复了，但很烦人。但不要将其与流程记录未存储在

里程碑

表中混淆。它只是进程id列。如果查看数据库中的值，就会很清楚

   @ManyToOne(fetch = FetchType.LAZY)
    @Transient
    private Process process;

        @SpringBootApplication
    public class AccessingDataJpaApplication {
        
        public static void main(String[] args) {
            ConfigurableApplicationContext context 
                    = SpringApplication.run(AccessingDataJpaApplication.class);
            ProcessService processService 
                    = context.getBean(ProcessService.class);
    
            Process process = new Process();
            process.setName("process-1");
    
            Milestone milestoneOne = new Milestone();
            milestoneOne.setProcess(process);
            milestoneOne.setName("milestone-1");
    
            Milestone milestoneTwo = new Milestone();
            milestoneTwo.setProcess(process);
            milestoneTwo.setName("milestone-2");
    
            process.setNodes(Arrays.asList(milestoneOne, milestoneTwo));
            processService.save(process);
            processService.findAll();
        }
    }

    @Service
    @Transactional
    public class ProcessService {
    
        @Autowired
        ProcessRepository processRepository;
    
        public Process save(Process process){
            return processRepository.save(process);
        }
    
        public List<Process> findAll(){
            List<Process> processes = processRepository.findAll();
            processes.forEach(System.out::println);
            
           //This prints the following
    
            // Process{id=1, name='process-1',
            // nodes=[Milestone{id=1, name='milestone-1'},
            //        Milestone{id=2, name='milestone-2'}]}

            return processes;
        }
    }

     @ManyToOne
     @JoinTable(
            name = "process_nodes",
            joinColumns = @JoinColumn(name = "process_id", 
                                      nullable = false, 
                                      insertable = false, 
                                      updatable = false),
            inverseJoinColumns = @JoinColumn(name = "node_id", 
                                           nullable = false, 
                                          insertable = false, 
                                          updatable = false)
    )
    @WhereJoinTable(clause = "node_type='milestone'")
    private Process process;