在运用中我们获得sesion 以
Session session = sessionFactory.getCurrentSession();
在这里如果我们采用thread方法对事务进行管理,即采用jdbc事务,那么sessionFactory的底层是通过ThreadLocalSessionContext类来获得session对象代码如下:
public org.hibernate.classic.Session getCurrentSession() throws HibernateException {
if ( currentSessionContext == null ) {
throw new HibernateException( "No CurrentSessionContext configured!" );
}
return currentSessionContext.currentSession();
}
其中currentSessionContext类型为ThreadLocalSessionContext
在ThreadLocalSessionContext的currentSession我们可见:
public final Session currentSession() throws HibernateException {
Session current = existingSession( factory );
if (current == null) {
current = buildOrObtainSession();
// register a cleanup synch
current.getTransaction().registerSynchronization( buildCleanupSynch() );
// wrap the session in the transaction-protection proxy
if ( needsWrapping( current ) ) {
current = wrap( current );
}
// then bind it
doBind( current, factory );//把当前的session和sessionFactory与当前线程关联
}
return current;
}
doBind()方法实现如下:
protected static Map sessionMap() {
return ( Map ) context.get();
}
private static void doBind(org.hibernate.Session session, SessionFactory factory) {
Map sessionMap = sessionMap();//sessionMap方法为获得与当前线程绑定的值,返回为Map类型
if ( sessionMap == null ) {
sessionMap = new HashMap();
context.set( sessionMap );
}
sessionMap.put( factory, session );//把factory和session放入与当前线程绑定的map中,这样,就形成了当前线程与session的传递关联。
}