_GenericDaoHibernateImpl<T> excerpt with session-safe getHibernateTemplate.save()

_GenericDaoHibernateImpl_excerpt.java

import java.lang.reflect.Method;


/**
 * Initialize any lazy-loaded member vars of the entity before saving. This is necessary 
 * because the session that supplies the lazy-loading will not be accessible here in the 
 * save() call if OpenSessionInView's singleSession=false. It uses one session for read-
 * only getters and another for save/updates.
 * 
 **/
@Override
public void save(T entity) {
    try {
        // Get all the public methods declared in the entity class plus inherited methods
        Method methods[] = clazz.getMethods();
        for (Method method: methods) {
            Package returnTypePackage = method.getReturnType().getPackage();
            
            // Only look at the getters whose return type is an entity object from my 
            //    hibernate-mapped domain.
            if (method.getName().startsWith("get") && returnTypePackage != null && returnTypePackage.getName().startsWith("com.essaytagger.model")) {
                
                // Only look at the simple no-arg getters - the goal here is to match the
                //    corresponding getMyPojo()/setMyPojo(myPojo) where myPojo might not be 
                //    initialized yet.
                if (method.toString().contains("()")) {
                    try {
                        // Grab the pojo from the getter
                        Object obj = method.invoke(entity);
                        
                        // If it isn't yet initialized...
                        if (obj instanceof HibernateProxy) {
                            
                            // ...initialize it!
                            getHibernateTemplate().initialize(obj);
                        }
                    } catch (Exception e) {
                        continue;
                    }
                }
            }
        }
    } catch (Throwable e) {
        log.debug(e);
    }
    
    // After all that we can now save without worrying about Session conflicts.
    getHibernateTemplate().save(entity);
}

Example1.java

Cat oldCat = catDao.get(oldCatId);

Cat newCat = new Cat();
newCat.setName("Whiskers");
newCat.setOwner(oldCat.getOwner());

catDao.save(newCat);    // Causes Session conflict because Owner isn't initialized

Example2.java

Cat oldCat = catDao.get(oldCatId);

// Pointless access to force Hibernate to initialize Owner.
oldCat.getOwner().getFirstName();

Cat newCat = new Cat();
newCat.setName("Whiskers");
newCat.setOwner(oldCat.getOwner());

catDao.save(newCat);    // Now everything goes smoothly.