public double getTotalCostInATime(String beginTime,String endTime){
		
		double totalCost=0.0;
		ArrayList<Object> receipts=this.show();
		for (Iterator iterator = receipts.iterator(); iterator.hasNext();) {
			SalesReceiptPO object = (SalesReceiptPO) iterator.next();
			if(changeDateToInt(object.getTime())>=changeDateToInt(beginTime)&&changeDateToInt(object.getTime())<=changeDateToInt(endTime)){
				//判断单据类型
				if(object.getSerialNumber().substring(0, 3).equals("XSD")){
					for(int i=0;i<object.getSalesList().size();i++){
						totalCost+=object.getSalesList().get(i).getGoodsPO().getPrice();//获得所有进价之和
					}
				}
			}			
		}
		
		return totalCost;
	}