blocks|key|1458810|text|如果您正在手动管理Hibernate会话，您可能需要在此处查看sessionFactory.getCurrentSession()和相关文档：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1458811|http://www.hibernate.org/hib_docs/v3/reference/en/html/architecture-current-session.html|offset|length|1458812|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|2G|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@$D|O|E|P|1|Q]]|A|$]]|$1|F|3|-4|5|6|7|R|8|@]|9|@]|A|$]]]|G|$H|$5|I|J|K|A|$L|C]]]]

If you are managing the Hibernate session manually, you may want to look into sessionFactory.getCurrentSession() and associated docs here:

<a href="http://www.hibernate.org/hib_docs/v3/reference/en/html/architecture-current-session.html" rel="nofollow noreferrer">http://www.hibernate.org/hib_docs/v3/reference/en/html/architecture-current-session.html</a>

blocks|key|1458852|text|好了，终于知道我疏忽到哪里去了。我有一个错误的想法，认为我应该将每个DAO方法包装在一个事务中。大错特错！我已经吸取了教训。我从所有DAO方法中提取了所有事务代码，并严格在应用程序/管理器层设置了事务。这完全解决了我所有的问题。数据在我需要的时候被适当地延迟加载，一旦我提交，就会被包装起来并关闭。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1458853|生活是美好的..。:)|1458854|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Okay, finally figured out where I was remiss. I was under the mistaken notion that I should wrap each DAO method in a transaction. Terribly wrong! I've learned my lesson. I've hauled all the transaction code from all the DAO methods and have set up transactions strictly at the application/manager layer. This has totally solved all my problems. Data is properly lazy loaded as I need it, wrapped up and closed down once I do the commit.

Life is goodly... :)

blocks|key|1458883|text|如果您使用的是延迟加载，则必须使用|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1458884|用于无状态会话EJB的@TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)|offset|length|style|CODE|1458885|entityMap^0|0|B|1O|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

if you are using Lazy loading your method must be annotated with 

<code>@TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)</code> for Stateless Session EJB

blocks|key|1458965|text|问题是，您正在尝试访问detached对象中的集合。在将集合访问到当前会话之前，需要重新附加对象。您可以通过以下方式完成此操作|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1458966|session.update(object);|code-block|syntax|javascript|1458967|使用lazy=false不是一个好的解决方案，因为您正在丢弃hibernate的延迟初始化特性。如果为lazy=false，则在请求对象的同时将集合加载到内存中。这意味着如果我们有一个包含1000个项目的集合，它们都将被加载到内存中，无论我们是否要访问它们。这可不是什么好事。|style|CODE|1458968|请阅读此article，其中解释了问题、可能的解决方案以及为什么以这种方式实现。此外，要理解会话和事务，您必须阅读this+other+article。|1458969|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.jboss.org/hibernate/core/3.3/reference/en/html/objectstate.html|1|http://community.jboss.org/wiki/OpenSessioninView|2|http://community.jboss.org/wiki/Sessionsandtransactions^0|B|8|0|0|0|2|A|1F|A|0|4|7|1|1L|I|2|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@$A|11|B|12|1|13]]|C|$]]|$1|D|3|E|5|F|7|14|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|15|8|@$A|16|B|17|K|L]|$A|18|B|19|K|L]]|9|@]|C|$]]|$1|M|3|N|5|6|7|1A|8|@]|9|@$A|1B|B|1C|1|1D]|$A|1E|B|1F|1|1G]]|C|$]]|$1|O|3|-4|5|6|7|1H|8|@]|9|@]|C|$]]]|P|$Q|$5|R|S|T|C|$U|V]]|W|$5|R|S|T|C|$U|X]]|Y|$5|R|S|T|C|$U|Z]]]]

The problem is that you are trying to access a collection in an object that is <a href="http://docs.jboss.org/hibernate/core/3.3/reference/en/html/objectstate.html" rel="noreferrer">detached</a>. You need to re-attach the object before accessing the collection to the current session. You can do that through

<pre><code>session.update(object);
</code></pre>

Using <code>lazy=false</code> is not a good solution because you are throwing away the Lazy Initialization feature of hibernate. When <code>lazy=false</code>, the collection is loaded in memory at the same time that the object is requested. This means that if we have a collection with 1000 items, they all will be loaded in memory, despite we are going to access them or not. And this is not good.

Please read this <a href="http://community.jboss.org/wiki/OpenSessioninView" rel="noreferrer">article</a> where it explains the problem, the possible solutions and why is implemented this way. Also, to understand Sessions and Transactions you must read <a href="http://community.jboss.org/wiki/Sessionsandtransactions" rel="noreferrer">this other article</a>.

blocks|key|1674044|text|如果您正在使用带有JPA注释的hibernate，那么这将非常有用。在您的服务类中，应该有一个带有@PersistenceContext的实体管理器的setter。将其更改为@PersistenceContext(类型=+PersistenceContextType.EXTENDED)。然后你可以在任何地方访问惰性属性。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1674045|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

If you are using hibernate with JPA annotations then this will be useful. In your service class there should be a setter for entity manager with @PersistenceContext. change this to @PersistenceContext(type = PersistenceContextType.EXTENDED). Then you can access lazy property in any where.

blocks|key|1674109|text|请看我的文章。我也遇到了同样的问题--+LazyInitializationException+--这是我最终想出的答案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1674110|http://community.jboss.org/wiki/LazyInitializationExceptionovercome|offset|length|1674111|设置lazy=false不是答案-它可以一次加载所有内容，这不一定是好的。示例：|1674112|1记录表A引用：|1674113|5记录表B引用：|1674114|25记录表C引用：|1674115|125记录表D|1674116|..。|1674117|等等。这只是可能出错的一个例子。|1674118|--蒂姆·萨宾|1674119|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|1V|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|13|8|@]|9|@$D|14|E|15|1|16]]|A|$]]|$1|F|3|G|5|6|7|17|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|18|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|19|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|1A|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|1B|8|@]|9|@]|A|$]]|$1|P|3|Q|5|6|7|1C|8|@]|9|@]|A|$]]|$1|R|3|S|5|6|7|1D|8|@]|9|@]|A|$]]|$1|T|3|U|5|6|7|1E|8|@]|9|@]|A|$]]|$1|V|3|-4|5|6|7|1F|8|@]|9|@]|A|$]]]|W|$X|$5|Y|Z|10|A|$11|C]]]]

See my article. I had the same problem - LazyInitializationException - and here's the answer I finally came up with: 
<a href="http://community.jboss.org/wiki/LazyInitializationExceptionovercome" rel="noreferrer">http://community.jboss.org/wiki/LazyInitializationExceptionovercome</a> 
Setting lazy=false is not the answer - it can load everything all at once, and that's not necessarily good. Example: 
1 record table A references: 
5 records table B references: 
25 records table C references: 
125 records table D 
... 
etc. This is but one example of what can go wrong. 
--Tim Sabin

blocks|key|1674160|text|对惰性字段使用Hibernate.initialize|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1674161|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

use Hibernate.initialize for lazy field

blocks|key|1459223|text|默认情况下，所有one-to-many和many-to-many关联在第一次访问时都会延迟获取。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1459224|在您的用例中，您可以通过将所有DAO操作包装到一个逻辑事务中来克服此问题：|1459225|transactionTemplate.execute(new+TransactionCallback<Void>()+{
++++@Override
++++public+Void+doInTransaction(TransactionStatus+transactionStatus)+{

++++++++int+startingCount+=+sfdao.count();

++++++++sfdao.create(+sf+);

++++++++SecurityFiling+sf2+=+sfdao.read(+sf.getId()+);

++++++++sfdao.delete(+sf+);

++++++++int+endingCount+=+sfdao.count();

++++++++assertTrue(+startingCount+==+endingCount+);
++++++++assertTrue(+sf.getId().longValue()+==+sf2.getId().longValue()+);
++++++++assertTrue(+sf.getSfSubmissionType().equals(+sf2.getSfSubmissionType()+)+);
++++++++assertTrue(+sf.getSfTransactionNumber().equals(+sf2.getSfTransactionNumber()+)+);

++++++++return+null;
++++}
});|code-block|syntax|javascript|1459226|另一种选择是在加载实体时获取所有延迟关联，以便：|1459227|SecurityFiling+sf2+=+sfdao.read(+sf.getId()+);|1459228|也应该获取懒惰的submissionType：|1459229|select+sf
from+SecurityFiling+sf
left+join+fetch.sf.submissionType|1459230|这样，您就可以急切地获取所有惰性属性，并且在会话关闭后也可以访问它们。|1459231|您可以获取尽可能多的[one%7Cmany]-to-one关联和一个“一对多”列表关联(因为运行笛卡尔乘积)。|1459232|要初始化多个“一对多”，你应该在加载你的根实体之后使用Hibernate.initialize(collection)。|1459233|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.jboss.org/hibernate/orm/4.3/javadocs/org/hibernate/Hibernate.html#initialize%2528java.lang.Object%2529^0|8|B|K|C|0|0|0|0|0|8|E|0|0|0|A|H|0|R|W|0|0^^$0|@$1|2|3|4|5|6|7|18|8|@$9|19|A|1A|B|C]|$9|1B|A|1C|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|1D|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|1E|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1F|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|1G|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|1H|8|@$9|1I|A|1J|B|C]]|D|@]|E|$]]|$1|S|3|T|5|J|7|1K|8|@]|D|@]|E|$K|L]]|$1|U|3|V|5|6|7|1L|8|@]|D|@]|E|$]]|$1|W|3|X|5|6|7|1M|8|@$9|1N|A|1O|B|C]]|D|@]|E|$]]|$1|Y|3|Z|5|6|7|1P|8|@]|D|@$9|1Q|A|1R|1|1S]]|E|$]]|$1|10|3|-4|5|6|7|1T|8|@]|D|@]|E|$]]]|11|$12|$5|13|14|15|E|$16|17]]]]

By default, all <code>one-to-many</code> and <code>many-to-many</code> associations are fetched lazily upon being accessed for the first time.

In your use case, you could overcome this issue by wrapping all DAO operations into one logical transaction:

<pre><code>transactionTemplate.execute(new TransactionCallback&lt;Void&gt;() {
 @Override
 public Void doInTransaction(TransactionStatus transactionStatus) {

 int startingCount = sfdao.count();

 sfdao.create( sf );

 SecurityFiling sf2 = sfdao.read( sf.getId() );

 sfdao.delete( sf );

 int endingCount = sfdao.count();

 assertTrue( startingCount == endingCount );
 assertTrue( sf.getId().longValue() == sf2.getId().longValue() );
 assertTrue( sf.getSfSubmissionType().equals( sf2.getSfSubmissionType() ) );
 assertTrue( sf.getSfTransactionNumber().equals( sf2.getSfTransactionNumber() ) );

 return null;
 }
});
</code></pre>

Another option is to fetch all LAZY associations upon loading your entity, so that:

<pre><code>SecurityFiling sf2 = sfdao.read( sf.getId() );
</code></pre>

should fetch the LAZY <code>submissionType</code> too:

<pre><code>select sf
from SecurityFiling sf
left join fetch.sf.submissionType
</code></pre>

This way, you eagerly fetch all lazy properties and you can access them after the Session gets closed too.

You can fetch as many <code>[one|many]-to-one</code> associations and one "[one|many]-to-many" List associations (because of running a Cartesian Product).

To initialize multiple "[one|many]-to-many", you should use <a href="https://docs.jboss.org/hibernate/orm/4.3/javadocs/org/hibernate/Hibernate.html#initialize%28java.lang.Object%29" rel="nofollow">Hibernate.initialize(collection)</a>, right after loading your root entity.

blocks|key|1459252|text|如果你使用Spring和JPA注解，避免延迟初始化中的会话问题的最简单的方法就是重放：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1459253|@PersistenceContext+++|code-block|syntax|javascript|1459254|至|1459255|@PersistenceContext(type+=+PersistenceContextType.EXTENDED)|1459256|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

If you using Spring and JPA annotation, the simpliest way to avoid problem with session in lazy initialize is replaysing:

<pre><code>@PersistenceContext 
</code></pre>

to

<pre><code>@PersistenceContext(type = PersistenceContextType.EXTENDED)
</code></pre>

Here's one that has me perplexed. I'm trying to implement a basic Hibernate DAO structure, but am having a problem.

Here's the essential code:

<pre><code>int startingCount = sfdao.count();
sfdao.create( sf );
SecurityFiling sf2 = sfdao.read( sf.getId() );
sfdao.delete( sf );
int endingCount = sfdao.count();

assertTrue( startingCount == endingCount );
assertTrue( sf.getId().longValue() == sf2.getId().longValue() );
assertTrue( sf.getSfSubmissionType().equals( sf2.getSfSubmissionType() ) );
assertTrue( sf.getSfTransactionNumber().equals( sf2.getSfTransactionNumber() ) );
</code></pre>

It fails on the third assertTrue where it's trying to compare a value in sf to the corresponding value in sf2. Here's the exception:

<pre><code>org.hibernate.LazyInitializationException: could not initialize proxy - no Session
 at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:86)
 at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:140)
 at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:190)
 at com.freightgate.domain.SecurityFiling_$$_javassist_7.getSfSubmissionType(SecurityFiling_$$_javassist_7.java)
 at com.freightgate.dao.SecurityFilingTest.test(SecurityFilingTest.java:73)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:40)
</code></pre>

hibernate: LazyInitializationException: could not initialize proxy

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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这里有一个让我感到困惑的问题。我正在尝试实现一个基本的Hibernate DAO结构，但遇到了一个问题。下面是必要的代码：int startingCount = sfdao.count();sfdao.create( sf );SecurityFiling sf2 = sfdao.read( sf.getId() );...

问hibernate: LazyInitializationException:无法初始化代理
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问hibernate: LazyInitializationException:无法初始化代理
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