本文是我用EJB+JPA(Hibernate实现)+Web Service开发时，遇到的一些问题，查了许多地方，都找不到答案，请各位朋友耐心读一下本文，有想法的欢迎留言！谢谢！ 

    Category.java的部分代码：

	@OneToMany(cascade={CascadeType.ALL},fetch=FetchType.LAZY,mappedBy="category")
public List<News> getNewsList() {
return newsList;
}
public void setNewsList(List<News> newsList) {
this.newsList = newsList;
}

    News.java的部分代码：

	@ManyToOne(cascade={CascadeType.PERSIST,CascadeType.MERGE},fetch=FetchType.EAGER)
@JoinColumn(name="cid")
public Category getCategory() {
return category;
}
public void setCategory(Category category) {
this.category = category;
}

   NewsDaoBean.java的部分代码：

	@PersistenceContext(unitName="newspstn")
private EntityManager em;
/**
* 添加新闻
* @param cid 项目编号
* @param news
*/
public void saveNews(int cid,News news) {
news.setCategory(em.find(Category.class, cid));
em.persist(news);
}
/**
* 查询所有新闻列表
* @return
*/
@SuppressWarnings("unchecked")
public List<News> listNews() {
return (List<News>)em.createQuery("from News n").getResultList();
}

    业务逻辑层的类（NewsManager.java）比较简单，由于篇幅问题，这里就不贴出来了。

    在还没有发布成Web Service前，用Juint测试：

                //测试保存新闻
public void testSaveNews() {
InitialContext ctx;
try {
ctx = new InitialContext();
NewsManager manager = (NewsManager)ctx.lookup("NewsManagerBean/remote");
News news = new News();
news.setTitle("title2");
news.setAuthor("author2");
news.setContent("content1");
manager.saveNews(1, news);
} catch (NamingException e) {
System.out.println("NamingException");
e.printStackTrace();
}
}
//测试查询新闻列表
public void testListNews() {
InitialContext ctx;
try {
ctx = new InitialContext();
NewsManager manager = (NewsManager)ctx.lookup("NewsManagerBean/remote");
List<News> newsList = manager.listNews();
for(News news : newsList){
System.out.println("news.title = " + news.getTitle());
}
} catch (NamingException e) {
System.out.println("NamingException");
e.printStackTrace();
}
}

   这个测试是没有问题的，(testSaveNews和testListNews)能正常添加和查询。

    当发布成Web Service后，在客户端生成相应的服务代理类，再在Web服务的客户端用Junit测试：

	//测试保存新闻
@Test
public void testSaveNews(){
NewsManagerService service = new NewsManagerService();
NewsManager manager = service.getNewsManagerPort();
News news = new News();
news.setTitle("title1");
news.setAuthor("author1");
news.setContent("content1");
manager.saveNews(1, news);
}
//测试查询新闻列表
@Test
public void testListNews(){
NewsManagerService service = new NewsManagerService();
NewsManager manager = service.getNewsManagerPort();
List<News> newsList = manager.listNews();     //------a1
for(News news : newsList) {                             //--------a2
System.out.println("news.title = " + news.getTitle());   //----a3
}                         //------a4
}

    这次测试，保存新闻的的操作（testSaveNews）能正常，但查询新闻列表（testListNews）的操作却抛以下异常：

12:19:37,781 INFO  [STDOUT] Hibernate:
select
news0_.id as id1_,
news0_.content as content1_,
news0_.cid as cid1_,
news0_.title as title1_,
news0_.author as author1_,
news0_.pubtime as pubtime1_
from
rong_news news0_
12:19:37,781 INFO  [STDOUT] Hibernate:
select
category0_.id as id0_0_,
category0_.cname as cname0_0_
from
rong_category category0_
where
category0_.id=?
12:19:37,796 ERROR [LazyInitializationException] failed to lazily initialize a collection of role: rong.entity.Category.newsList, no session or session was closed
org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: rong.entity.Category.newsList, no session or session was closed
（……相关的异常堆栈信息略……）
12:19:37,796 ERROR [RequestHandlerImpl] Error processing web service request
org.jboss.ws.WSException: javax.xml.ws.WebServiceException: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: rong.entity.Category.newsList, no session or session was closed
（……相关的异常堆栈信息略……）
Caused by: javax.xml.ws.WebServiceException: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: rong.entity.Category.newsList, no session or session was closed
（……相关的异常堆栈信息略……）
Caused by: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: rong.entity.Category.newsList, no session or session was closed
（……相关的异常堆栈信息略……）
12:19:37,890 ERROR [[NewsManagerBean]] Servlet.service() for servlet NewsManagerBean threw exception
org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: rong.entity.Category.newsList, no session or session was closed
（……相关的异常堆栈信息略……）

补充说明1：如果我把上面testListNews方法中的a1,a2,a3,a4行注释掉，Junit测试是正常的。

补充说明2：在Category类中，对List<News> newsList的设置，我确定是设置了延迟加载(Lazy)的，而且，我在查询 新闻列表时，没有用到news.getCategory.getNewsList()之类的操作。有个疑问：是不是设置的lazy加载，即使没有用到，也会加载的？即使会加载的，为什么我在服务器端测试时能正常，而在Web Service的客户端测试时，却报错？

是EJB Web Service的Bug还是我的程序有错误？请大家讨论！