ex7_24.txt

j2ee core design patterns

Example 7.24 Implementing Lazy Loading strategy

	...
	public Collection getSkillSetsData() {
	throws SkillSetException {
		checkSkillSetLoad();
		return skillSets;
	}

	private void checkSkillSetLoad() 
	throws SkillSetException {
		try {
			// Lazy Load strategy...Load on demand
			if (skillSets == null)
				skillSets =
					getSkillSetDAO().findAllSkills(resourceId);
		} catch (Exception exception) {
			// No skills, throw an exception 
			throw new SkillSetException(...);
		}
	}

	...

	public void ejbLoad() {
		try {
			// load the resource info from
			ResourceDAO resourceDAO = new ResourceDAO();
			setResourceData(
				resourceDAO.findResource(employeeId));
			
			// If the lazy loaded objects are already
			// loaded, they need to be reloaded.
			// If there are not loaded, do not load them
			// here...lazy load will load them later.
			if (skillSets != null) {
				reloadSkillSets();
			}
			if (blockOutTimes != null) {
				reloadBlockOutTimes();
			}
			...
			throw new EJBException("Reason:"+...);
		}
	}
	
	...