c#中操作Xml

//取xml数据，导入法规类型
public bool ImpLawType(IList alLawTypeID,string fileName)
{
    bool flag = true;
    IList alLawType = new ArrayList();

    //定义Xml文档
    XmlDocument xd = new XmlDocument();
    xd.Load(fileName);
    XmlNodeList xnl = xd.SelectNodes("/LawSystem/LawType/Table");

    foreach (int lawTypeID in alLawTypeID)
    {
        //实例化法规类型
        foreach( XmlNode xn in xnl)
        {
            XmlNode nodeID = xn.SelectSingleNode("law_type_id");
            if (lawTypeID == Convert.ToInt32(nodeID.InnerText))
            {
                LawTypeInfo lawTypeInfo = new LawTypeInfo();

                //定义节点
                XmlNode nodeTypeName = xn.SelectSingleNode("law_type_name");
                XmlNode nodeUID = xn.SelectSingleNode("user_id");
                XmlNode nodeBrief = xn.SelectSingleNode("law_type_Brief");
                XmlNode nodeCreateTime = xn.SelectSingleNode("create_time");
                XmlNode nodeCreateName = xn.SelectSingleNode("create_name");

                //实体赋值
                lawTypeInfo.LawTypeId = lawTypeID;
                lawTypeInfo.LawTypeName = nodeTypeName.InnerText;
                lawTypeInfo.UserID = Convert.ToInt32(nodeUID.InnerText);
                lawTypeInfo.LawTypeBrief = nodeBrief.InnerText;
                lawTypeInfo.CreateTime = nodeCreateTime.InnerText;
                lawTypeInfo.CreateName = nodeCreateName.InnerText;

                alLawType.Add(lawTypeInfo);
            }
        }
    }
    //保存数据
    try
    {
        foreach (LawTypeInfo lawTypeInfo in alLawType)
        {
            (new LawTypes()).Insert(lawTypeInfo);
        }

        flag = true;
    }
    catch(Exception ex)
    {
        throw ex;
    }

    return flag;
}

//导出为Xml格式数据
public string GetLawTypeXml(ArrayList lawTypeIds, string memo)
{
     //xml头
     StringBuilder xml = new StringBuilder();
     xml.Append("<LawSystem>\n");
     xml.Append("<Info>\n");
     xml.Append("<memo>" + memo     + "</memo>\n");
     xml.Append("</Info>\n");
 
     //法规类型
     int lawTypeNum = 0;
     foreach(string id in lawTypeIds)
     {
          int lawTypeId = Convert.ToInt32(id);
          StringBuilder sb = new StringBuilder();
          //GetXml返回值为DataSet调用GetXml（）格式化为Xml格式，
          //（注：给DataSet.TableName赋初值）
          sb.Append((new LawType()).GetXml(lawTypeId));
          //法规
          sb.Insert(sb.Length - 21, (new Law()).GetXml(lawTypeId));
  
          xml.Append(sb.ToString());

          onSendMsg(++lawTypeNum,0,0);//触发事件给进度条赋值
     }

     xml.Append("</LawSystem>");
 
     return xml.ToString();//返回
 
     string xmlStr = xml.ToString();
     sw = new StreamWriter(fileName);//fileName带全路径
     sw.Write(xmlStr);
}