关于强制转换成 Map 取值的问题。困扰了一天了，大家帮帮忙

public static void main(String[] args) throws  Exception {

		

		Map openParaMap = new HashMap();

		Map resultMap = new HashMap();

		List offerList = new ArrayList();

		offerList.add("111001002364");

		openParaMap.put("BILL_ID", "18811520894_NET");

		openParaMap.put("OFFER_ID", offerList);

		openParaMap.put("OP_TYPE", "CREATE");

		openParaMap.put("CHANNEL_TYPE", "7"); 

		openParaMap.put("EFF_DATE", null);

		openParaMap.put("EXP_DATE", null);

		

		Map offerAttrMaps = new HashMap(); 

		Map offerAttr = new HashMap();



		offerAttr.put("222222222", "18811520894");

		offerAttr.put("333333333", "test_mac_001"); // mac地址

		offerAttr.put("444444444", "197031001"); // 物料编码

		offerAttr.put("666666666", "0"); 

		offerAttrMaps.put("111001002364", offerAttr);

		openParaMap.put("ATTRS", offerAttrMaps);

		testMap(openParaMap);

	}

	



	public static void testMap(Map openParaMap){

		ArrayList offerId = (ArrayList) openParaMap.get("OFFER_ID");

		Object attrMapsObj = openParaMap.get("ATTRS");

		Map attrMaps = (HashMap)attrMapsObj;

		Iterator iter = (Iterator) attrMaps.keySet().iterator();

		 while (iter.hasNext()) {

			 	String iterOffer = String.valueOf(iter.next());

				 Map attrMap = (HashMap) attrMaps.get(String.valueOf(iterOffer));

				 Iterator iterAttr = (Iterator) attrMap.keySet().iterator();

				 while(iterAttr.hasNext()){

						//拼接属性

					 String attrId = String.valueOf(iterAttr.next());

					 String value = (String)attrMap.get(attrId);

					 System.out.println(attrId + ": " + value);

				 }

		 }

	}