我在休眠中更新和显示数据时遇到了一个奇怪的问题。谁能帮帮我！？
我正在使用hibernate，spring和mysql。
我面临的问题是，任何更改都可以应用于数据库。但是如果我在网页上加载更新的项目，它总是随机返回旧数据或新数据。
我确信这不是浏览器缓存的问题。我试图在 dao 类的 getPost 方法中打印出返回数据。它有时只是打印出错误消息。
比如说，如果我多次更改帖子内容，所有更改都可以存储在数据库中。但是如果我不断刷新页面以显示更改的数据，它会随机显示所有以前的更改。
我尝试了不同的方法在 getPost 方法中加载数据，但仍然面临同样的问题：
尝试过 session.clear 和 session.flush
关闭二级缓存为：
<prop key="hibernate.cache.use_second_level_cache">false</prop> <prop key="hibernate.cache.use_query_cache">false</prop> <prop key="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider</prop> <prop key="hibernate.cache.use_structured_entries">false</prop>加载数据的不同方式：session.load、session.get、hibernate query、Criteria，都有相同的问题。
在 postDAO 的 getPost 方法中：我先尝试通过原生 SQL 加载数据，并想与休眠查询的结果进行比较。两个查询都返回旧数据。
代码：
public class Post implements Cloneable, Serializable {
private String postID;
private String content;
}
PostSelectController (controller):
public class PostSelectController extends AbstractController
{
....
protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response) throws Exception
{
String id = request.getParameter("id");
Course course = null;
Vendor vendor = null;
Post post = null;
ModelAndView modelAndView = new ModelAndView();
modelAndView.setViewName(getSuccessView());
post = postService.getPost(id);
modelAndView.addObject("post", post);
return modelAndView;
}
}
postService:
@Transactional(propagation=Propagation.SUPPORTS, isolation=Isolation.READ_COMMITTED, readOnly=true)
public class PostService
{
@Transactional(propagation=Propagation.REQUIRED, readOnly=false)
public boolean updatePost(Post post) {
System.out.println("service side::::::::::::::::::::::"+(post.getBestAnswer()!=null));
if(post.getBestAnswer()!=null) System.out.println(">>>>>>>>"+post.getBestAnswer().getPostID());
System.out.println("service side::::::::::::::::::::::"+(post.getBestAnswer()!=null));;
return this.postDAO.updatePost(post);
}
public Post getPost(String postID) {
return this.postDAO.getPost(postID);
}
}
postDAO:
public class PostDAO {
private SessionFactory sessionFactory;
...
public boolean updatePost(Post post) {
boolean proceed = true;
try {
Session session = sessionFactory.getCurrentSession();
session.merge(post); //tried session.update, same problem
session.flush(); //it does not help
} catch (Exception ex) {
logger.error(post.getPostID() + " refused :: " + ex.getMessage());
proceed = false;
}
return proceed;
}
public Post getPost(String postID) {
Session session = sessionFactory.getCurrentSession();
try{
PreparedStatement st = session.connection()
.prepareStatement("select content from post where postid='"+postID+"'") ;
ResultSet rs =st.executeQuery();
while (rs.next()) {
System.out.println("database::::::::::::::::::"+rs.getInt("content"));
// tried to use native sql to load data from database and compare it with result of hibernate query.
break;
}
}catch(Exception ex){
}
Criteria crit = session.createCriteria(Post.class);
NaturalIdentifier natId = Restrictions.naturalId();
natId.set("postID", postID);
crit.add(natId);
crit.setCacheable(false);
List<Post> posts = crit.list();
Post post = null;
if(posts!=null) post = posts.get(0);
System.out.println("hibernate::::::::::::::::::"+post.getContent());
return post;
}