使用ClassMetadata确定ManyToMany与OneToMany [英] Determining ManyToMany vs OneToMany using ClassMetadata

问题描述

我使用ClassMetadata来确定一个hibernate POJO的结构。

I am using ClassMetadata to determine the structure of a hibernate POJO.

我需要确定一个集合是OneToMany还是ManyToMany。这些信息在哪里？我可以在不使用反射的情况下使用它吗？看到我的代码如下。

I need to determine if a collection is OneToMany or ManyToMany. Where is this information? Can I get to it without using reflection? See my code below.

//Get the class' metadata
ClassMetadata cmd=sf.getClassMetadata(o.getClass());

for(String propertyName:cmd.getPropertyNames()){
    if (cmd.getPropertyType(propertyName).isCollectionType() && cmd.??()) //Do something with @ManyToMany collections.
}

我需要的是告诉我它是否是ManyTo____关系的方法。我看到getPropertyLaziness（），但这并不总是保证集合的类型。任何想法？

All I need is method to tell me if it's a ManyTo____ relationship. I see getPropertyLaziness(), but that doesn't always guarantee the type of collection. Any ideas?

推荐答案

这并不那么简单，不幸的是。检测这种情况的最佳方法是检查特定的 CollectionPersister 实现：

It's not that simple, unfortunatelly. Your best bet to detect this is by checking for particular CollectionPersister implementation:

SessionFactory sf = ...;

// Get the class' metadata
ClassMetadata cmd = sf.getClassMetadata(o.getClass());

for(String propertyName:cmd.getPropertyNames()) {
  Type propertyType = cmd.getPropertyType(propertyName);
  if (propertyType.isCollectionType()) {
    CollectionType collType = (CollectionType) propertyType;

    // obtain collection persister
    CollectionPersister persister = ((SessionFactoryImplementor) sf)
      .getCollectionPersister(collType.getRole());

    if (persister instanceof OneToManyPersister) {
      // this is one-to-many
    } else {
     // this is many-to-many OR collection of elements
    }
  } // if
} // for

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