/**
     * 设置对象的修改者
     * @param obj  Persistence对象
     * @param uref WTPrincipalReference对象
     * @throws Exception
     */
    public static void setModifier(Iterated obj, WTPrincipalReference uref) throws Exception {
		try {
			obj.getCreator();
			Class[] pp = new Class[] { WTPrincipalReference.class };
			Method setCreator = _IterationInfo.class.getDeclaredMethod("setModifier", pp);
			setCreator.setAccessible(true);
			setCreator.invoke(obj.getIterationInfo(), new Object[] { uref });
		} catch (Exception e) {
			// System.out.println(">>>Error:" + e.toString());
			e.printStackTrace();
			throw e;
		}

	}

例子：

/*
*1）先根据用户名获取到用户
*2）根据WTUser对象New一个WTPrincipalReference  
*3）调用setModifier（）方法更新对象的修改者，**记得在设置对象修改者前刷新下对象拿到最新版本**
*4）因为修改者只是对象的一个属性，设置成功后需要自己调用方法持久化对象
*5）**两种持久化方法**：
	A:PersistenceServerHelper.manager.*;----PersistenceServerHelper相对简单粗暴，单纯执行
	    PersistenceServerHelper.manager.insert(partAfter);
	    PersistenceServerHelper.manager.update(partAfter);
	    PersistenceServerHelper.manager.remove(partAfter);
	    PersistenceServerHelper.manager.restore(partAfter);
	    PersistenceServerHelper.manager.store(Persistable arg0, Timestamp arg1, Timestamp arg2);
	    
	B:PersistenceHelper.manager.*;--PersistenceHelper执行时，考虑全面，如权限，关联对象,标准用法
	PersistenceHelper.manager.save（Persistable）
	PersistenceHelper.manager.delete（Persistable）
	PersistenceHelper.manager.store（Persistable）
	PersistenceHelper.manager.refresh（Persistable）;
*/
	WTUser user = getUserByName(“Wonly.Wu”);
	WTPrincipalReference  uref =WTPrincipalReference.newWTPrincipalReference(user);
	wt.part.WTPart partBefore =getPartByNumber(beforeNumber);
	partBefore = (WTPart) PersistenceHelper.manager.refresh(partBefore);
	setModifier(partBefore, uref);
    PersistenceServerHelper.manager.update(partBefore);

public static WTUser getUserByName(String name){
    	WTUser user = null;   
    	try {
    		QuerySpec qs = new QuerySpec(WTUser.class);
			SearchCondition sc = new SearchCondition(WTUser.class,WTUser.NAME, SearchCondition.EQUAL, name, false);
			qs.appendSearchCondition(sc);			
			
			QueryResult qr = PersistenceHelper.manager.find(qs);
			if (qr.hasMoreElements()){
				user = (WTUser)qr.nextElement();
			}
			
			if(user == null)
				user = OrganizationServicesHelper.manager.getUser(name);				
			
		} catch (Exception e) {
			e.printStackTrace();
		}
    	return user;
    }

/**
	 * Answer a part by for a given part number
	 * @param partNumber - the String object used as search criteria in the retrieval of WTPart  
	 * @return WTPart
	 */
	public static WTPart getPartByNumber(String partNumber){
		WTPart part = null;
		try{
			WTPartMaster partMaster = getPartMasterByNumber(partNumber);
			if(partMaster == null){
				return null;
			}
			QueryResult qr = VersionControlHelper.service.allIterationsOf((Master)partMaster);
			if (qr.hasMoreElements()){
				part = (WTPart)qr.nextElement();
			}
		}catch(Exception ex){
			ex.printStackTrace();
			System.out.println("TAPart.class Method=getPartByNumber,number is ="+partNumber+" Exception Message = " + ex.getMessage()); //Debug
		}
		return part;
	}

/**
	 * Answer a part by for a given part number
	 * @param partNumber - the String object used as search criteria in the retrieval of WTPart  
	 * @return WTPart
	 * 
	 */
	public static WTPartMaster getPartMasterByNumber(String partNumber){
		WTPartMaster partMaster = null;
		try{						
			QuerySpec qs = new QuerySpec(WTPartMaster.class);			
			SearchCondition sc = new
					SearchCondition(WTPartMaster.class, WTPartMaster.NUMBER, 
							SearchCondition.EQUAL,StringUtils.trim(partNumber),false);
			qs.appendSearchCondition(sc);
			QueryResult qr = PersistenceHelper.manager.find(qs);
			if (qr.hasMoreElements()){				
				partMaster = (WTPartMaster)qr.nextElement();
			}
		}catch(Exception e){
			e.printStackTrace();
			System.out.println("TAPart.class Method=getPartMasterByNumber Exception Message = " + e.getMessage()); //Debug
		}
		return partMaster;
	}