使用gson 將連結串列儲存的優化轉化：

	private Gson gson = new Gson();
	
	private void readStr(){
		List<ContactsBeanInfo> contacts = null;
		if (!TextUtils.isEmpty(str) && !init) {
				contacts = gson.fromJson(str,
				new TypeToken<List<ContactsBeanInfo>>() {}.getType());// 把JSON格式的字串轉為List
		}
	}	
	private void savaContacts() {
		String list = gson.toJson(contactsList);
		SharedPrefsUtil.putSetStringValue(mContext, SystemParamHelper
				.getInstance().getAccountID() + SharedPrefsUtil.CONTACTS_DATA,
				list);
		SharedPrefsUtil.putSetBooleanValue(mContext, SystemParamHelper
				.getInstance().getAccountID() + SharedPrefsUtil.INIT_CONTACTS,
				false);
	}