处理LazyInitializationException的最好方法是在查询时加入取回，像这样:

select t
from Topic t
left join fetch t.comments

您应该始终避免以下反模式:

FetchType。急切的 OSIV (Open Session in View) 冬眠。enable_lazy_load_no_trans Hibernate配置属性

因此，确保你的FetchType。LAZY关联在查询时或使用Hibernate在原始的@Transactional范围内初始化。初始化辅助集合。

此问题是由于在关闭hibernate会话的情况下访问属性造成的。控制器中没有hibernate事务。

可能的解决方式:

Do all this logic, in the service layer, (with the @Transactional), not in the controller. There should be the right place to do this, it is part of the logic of the app, not in the controller (in this case, an interface to load the model). All the operations in the service layer should be transactional. i.e.: Move this line to the TopicService.findTopicByID method: Collection commentList = topicById.getComments(); Use 'eager' instead of 'lazy'. Now you are not using 'lazy' .. it is not a real solution, if you want to use lazy, works like a temporary (very temporary) workaround. use @Transactional in the Controller. It should not be used here, you are mixing service layer with presentation, it is not a good design. use OpenSessionInViewFilter, many disadvantages reported, possible instability.

一般来说，最佳解是1。

为了延迟加载集合，必须有一个活动会话。在web应用中，有两种方法可以做到这一点。您可以使用Open Session In View模式，其中使用拦截器在请求开始时打开会话，并在结束时关闭会话。风险在于你必须有可靠的异常处理，否则你可能会绑定所有的会话，你的应用程序可能会挂起。

The other way to handle this is to collect all the data you need in your controller, close your session, and then stuff the data into your model. I personally prefer this approach, as it seems a little closer to the spirit of the MVC pattern. Also if you get an error from the database this way you can handle it a lot better than if it happens in your view renderer. Your friend in this scenario is Hibernate.initialize(myTopic.getComments()). You will also have to reattach the object to the session, since you're creating a new transaction with every request. Use session.lock(myTopic,LockMode.NONE) for that.

我知道这是个老问题，但我想帮忙。 可以将事务注释放在所需的服务方法上，在本例中findTopicByID(id)应该具有

@Transactional(propagation=Propagation.REQUIRED, readOnly=true, noRollbackFor=Exception.class)

关于这个注释的更多信息可以在这里找到

关于其他解决方案:

fetch = FetchType.EAGER 

这不是一个好的做法，只有在必要时才应该使用。

Hibernate.initialize(topics.getComments());

hibernate初始化器将类绑定到hibernate技术。如果你的目标是灵活并不是一个好方法。

希望能有所帮助

为了解决这个问题，在我的例子中，它只是少了这一行

<tx:annotation-driven transaction-manager="myTxManager" />

在应用程序上下文文件。

方法上的@Transactional注释没有考虑在内。

希望这个答案能帮助到一些人

如果你知道你想在每次检索主题时看到所有的注释，那么将注释的字段映射更改为:

@OneToMany(fetch = FetchType.EAGER, mappedBy = "topic", cascade = CascadeType.ALL)
private Collection<Comment> comments = new LinkedHashSet<Comment>();

默认情况下，集合是惰性加载的，如果你想了解更多，可以看看这个。