JPA中管理双向关系的java问题：从集合中删除

Question

我的域模型与实体中的关系管理具有自参考双向关系：

@Entity
public class Users implements BaseEntity<String>, Serializable {

    @Id
    private String username;
    @ManyToMany(cascade = {CascadeType.REFRESH, CascadeType.MERGE, CascadeType.PERSIST})
    private List<User> associatedSenders;
    @ManyToMany(mappedBy = "associatedSenders")
    private List<User> associatedReceivers;

    //
    // Associated Senders
    //
    public List<User> getAssociatedSenders() {
        if (associatedSenders == null) {
            associatedSenders = new ArrayList<User>();
        }

        return associatedSenders;
    }

    public void addAssociatedSender(User sender) {
        if (associatedSenders == null) {
            associatedSenders = new ArrayList<User>();
        }

        associatedSenders.add(checkNotNull(sender));
        if (!sender.getAssociatedReceivers().contains(this)) {
            sender.addAssociatedReceiver(this);
        }
    }

    public void removeAssociatedSender(User sender) {
        if (associatedSenders == null) {
            associatedSenders = new ArrayList<User>();
        }

        associatedSenders.remove(checkNotNull(sender));
        if (sender.getAssociatedReceivers().contains(this)) {
            sender.removeAssociatedReceiver(this);
        }
    }

    public void setAssociatedSenders(List<User> senders) {
        checkNotNull(senders);

        if (associatedSenders == null) {
            associatedSenders = new ArrayList<User>();
        }

        // first remove all previous senders
        for (Iterator<User> it = associatedSenders.iterator(); it.hasNext();) {
            User sender = it.next();
            it.remove();
            if (sender.getAssociatedReceivers().contains(this)) {
                sender.removeAssociatedReceiver(this);
            }
        }

        // now add new senders
        for (User sender : senders) {
            addAssociatedSender(sender);
        }
    }

    //
    // Associated Receivers
    //
    public List<User> getAssociatedReceivers() {
        if (associatedReceivers == null) {
            associatedReceivers = new ArrayList<User>();
        }

        return associatedReceivers;
    }

    /**
     * <p><b>Note:</b> this method should not be used by clients, because it
     * does not manage the inverse side of the JPA relationship. Instead, use
     * the appropriate method at the inverse of the relationship.
     * 
     * @param receiver
     */
    protected void addAssociatedReceiver(User receiver) {
        if (associatedReceivers == null) {
            associatedReceivers = new ArrayList<User>();
        }

        associatedReceivers.add(checkNotNull(receiver));
    }

    /**
     * <p><b>Note:</b> this method should not be used by clients, because it
     * does not manage the inverse side of the JPA relationship. Instead, use
     * the appropriate method at the inverse of the relationship.
     *
     * @param receiver
     */
    protected void removeAssociatedReceiver(User receiver) {
        if (associatedReceivers == null) {
            associatedReceivers = new ArrayList<User>();
        }

        associatedReceivers.remove(checkNotNull(receiver));
    }
}

当我向associatedSenders集合添加新的用户实体时，一切都按预期进行。数据库中的表得到正确更新，内存中的关系也正确。但是，当我从associatedSenders集合中删除一个用户实体（或该集合中的所有实体）时，例如，通过这样的调用：

List<User> senders = Collections.emptyList();
user.setAssociatedSenders(senders)

数据库表得到了正确的更新，但对em.find(User.class, username)的下一次调用username是以前在associatedSenders集合中的用户的id，显示associatedReceivers集合（反面）没有正确更新。也就是说，user仍在该集合中。只有通过em.refresh()刷新实体时，集合才会正确更新。看起来实体管理器在这里进行了一些缓存，但我觉得这种行为不正确

更新可能值得一提的是，我正在修改JSF托管bean中前端的用户实体，即当实体处于分离状态时