[Silverlight入门系列]Silverlight读取XElement

Silverlight由于用的是Silverlight版的.NET Framework，不是完整版，所以在Silverlight下面处理xml有点不一样。XmlDocument没有了，取而代之的是XDocument，是Linq的东东，使用起来还是很方便的：

XDocument xmlProducts = XDocument.Parse(xmlContent);
var products = from product in xmlProducts.Descendants("Product")
                  select new
                   {
                     ProductID = Convert.ToInt32(product.Element("ProductId").Value),
                     ProductName = (string)product.Element("ProductName").Value
                   };

XElement是XDocument下面的东东，XDocument可以添加它：

StringBuilder output = new StringBuilder();
XElement srcTree = new XElement("Root",
    new XElement("Element1", 1),
    new XElement("Element2", 2),
    new XElement("Element3", 3),
    new XElement("Element4", 4),
    new XElement("Element5", 5)
);
XElement xmlTree = new XElement("Root",
    new XElement("NewElement", "Content")
);
xmlTree.Add(
    from el in srcTree.Elements()
    where (int)el >= 3
    select el
);
output.Append(xmlTree + Environment.NewLine);

OutputTextBlock.Text = output.ToString();

 

当然，XElement也可以从xml文件加载：

private void Page_Loaded(object sender, RoutedEventArgs e)
{
    DataGrid1.ItemsSource = GetStatusReport();
}

public List<Status> GetStatusReport()
{
    List<Status> statusReport = new List<Status>();

    XElement doc = XElement.Load(@"Data/StatusReport.xml");

    statusReport = (from el in doc.Elements()
                    select GetStatus(el)).ToList();

    return statusReport;
}

private Status GetStatus(XElement el)
{
    Status s = new Status();
    s.Description = el.Attribute("Description").Value;
    s.Date = DateTime.Parse(el.Attribute("Date").Value);
    return s;
}

 

在WCF Ria Service的DomainService可以返回一个XElement类型的数据，它比XDocument更便携：

[Invoke]
[RequiresAuthentication]
public XElement TestDomainService(string param)
{
    var query = ... // linq query...
    return query.Value.ToArray().AsXml(true).Root; //return XElement
}

 

返回的XElement假设是这样的XML：

<Shuttle xmlns="">
  <shuttleVersion>0101</shuttleVersion>
  <shuttleDate Name="CrashAT__01">
    <job>CRASHME</job>
    <param></param>
    <startDateTime>0000000000</startDateTime>
    <executeInterval>01</executeInterval>
    <executeNext>0000000000</executeNext>
    <errorRepetitionNumber>03</errorRepetitionNumber>
    <errorRepetitionInterval>05</errorRepetitionInterval>
    <currentErrorRepitionNumber>00</currentErrorRepitionNumber>
    <shuttleListValue>0000</shuttleListValue>
    <executeNextDetail>0000000000</executeNextDetail>
    <shuttleListList>
      <shuttleList Name="ALL_0100_0600">
        <shuttleListWeekday>ALL</shuttleListWeekday>
        <shuttleListStart>0100</shuttleListStart>
        <shuttleListEnd>0600</shuttleListEnd>
      </shuttleList>
    </shuttleListList>
  </shuttleDate>
</Shuttle>

 

如何读取XElement？如何用递归把上面的XML转换为树形的无限极的实体类呢？最方便的当然是用xml.linq。另外一种方法是用XmlReader:

using (var reader = XmlReader.Create(new StringReader(xmlElement.ToString(SaveOptions.None))))
{
    while (reader.Read())
    {
        if (reader.NodeType != XmlNodeType.Element) continue;

        //From 1st line to last line, including comments, EndElement...
        //....
     }
}

 

无限递归XElement - XElement.Elements()

还有一种方法是递归XElement – XElment.Elements()，如果你需要把XElement转为树形复合结构的类列表（类下面有子类，无限层级），需要用这个方法:

//入口函数
private IEnumerable<<YourEntity> GetAllNodes(XElement element)
{
    IList<YourEntity> ret = new List<YourEntity>();

    foreach (var elem in element.Elements())
    {
        if (elem.HasElements)
        {
            var node = CreateNode(elem);

            foreach (var item in CreateNodeCollection(elem)) // 这里面有递归
            {
                node.Children.Add(item);
            }
            ret.Add(node);
        }
        else
        {
            ret.Add(CreateNode(elem));
        }

    }
    return ret;
}

//递归调用
private IEnumerable<YourEntity> CreateNodeCollection(XElement element)
{
    IList<YourEntity> ret = new List<YourEntity>();

    foreach (XElement elem in element.Elements())
    {
        if (elem.HasElements)
        {
            var node = CreateNode(elem);
            foreach (var item in CreateNodeCollection(elem))
            {
                node.Children.Add(item);
            }
            ret.Add(node);
        }
        else
        {
            ret.Add(CreateNode(elem, param));
        }
    }
    return ret;
}

private YourEntity CreateNode(XElement element)
{
    var ret = new YourEntity();
    ret.Name = element.Name.ToString();
    ret.Value = element.Value;
    ret.Tag = element.HasAttributes ? element.FirstAttribute.Value : element.Value;
    return ret;
}