[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：

   1: XDocument xmlProducts = XDocument.Parse(xmlContent);

   2: var products = from product in xmlProducts.Descendants("Product")

   3:                   select new

   4:                    {

   5:                      ProductID = Convert.ToInt32(product.Element("ProductId").Value),

   6:                      ProductName = (string)product.Element("ProductName").Value

   7:                    }; 

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

   1: StringBuilder output = new StringBuilder();

   2: XElement srcTree = new XElement("Root",

   3:     new XElement("Element1", 1),

   4:     new XElement("Element2", 2),

   5:     new XElement("Element3", 3),

   6:     new XElement("Element4", 4),

   7:     new XElement("Element5", 5)

   8: );

   9: XElement xmlTree = new XElement("Root",

  10:     new XElement("NewElement", "Content")

  11: );

  12: xmlTree.Add(

  13:     from el in srcTree.Elements()

  14:     where (int)el >= 3

  15:     select el

  16: );

  17: output.Append(xmlTree + Environment.NewLine);

  18:  

  19: OutputTextBlock.Text = output.ToString();

 

当然，XElement也可以从xml文件加载：

   1: private void Page_Loaded(object sender, RoutedEventArgs e)

   2: {

   3:     DataGrid1.ItemsSource = GetStatusReport();

   4: }

   5:  

   6: public List<Status> GetStatusReport()

   7: {

   8:     List<Status> statusReport = new List<Status>();

   9:  

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

  11:  

  12:     statusReport = (from el in doc.Elements()

  13:                     select GetStatus(el)).ToList();

  14:  

  15:     return statusReport;

  16: }

  17:  

  18: private Status GetStatus(XElement el)

  19: {

  20:     Status s = new Status();

  21:     s.Description = el.Attribute("Description").Value;

  22:     s.Date = DateTime.Parse(el.Attribute("Date").Value);

  23:     return s;

  24: }

 

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

   1: [Invoke]

   2: [RequiresAuthentication]

   3: public XElement TestDomainService(string param)

   4: {

   5:     var query = ... // linq query...

   6:     return query.Value.ToArray().AsXml(true).Root; //return XElement

   7: }

 

返回的XElement假设是这样的XML：

   1: <Shuttle xmlns="">

   2:   <shuttleVersion>0101</shuttleVersion>

   3:   <shuttleDate Name="CrashAT__01">

   4:     <job>CRASHME</job>

   5:     <param></param>

   6:     <startDateTime>0000000000</startDateTime>

   7:     <executeInterval>01</executeInterval>

   8:     <executeNext>0000000000</executeNext>

   9:     <errorRepetitionNumber>03</errorRepetitionNumber>

  10:     <errorRepetitionInterval>05</errorRepetitionInterval>

  11:     <currentErrorRepitionNumber>00</currentErrorRepitionNumber>

  12:     <shuttleListValue>0000</shuttleListValue>

  13:     <executeNextDetail>0000000000</executeNextDetail>

  14:     <shuttleListList>

  15:       <shuttleList Name="ALL_0100_0600">

  16:         <shuttleListWeekday>ALL</shuttleListWeekday>

  17:         <shuttleListStart>0100</shuttleListStart>

  18:         <shuttleListEnd>0600</shuttleListEnd>

  19:       </shuttleList>

  20:     </shuttleListList>

  21:   </shuttleDate>

  22: </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:

   1: using (var reader = XmlReader.Create(new StringReader(xmlElement.ToString(SaveOptions.None))))

   2: {

   3:     while (reader.Read())

   4:     {

   5:         if (reader.NodeType != XmlNodeType.Element) continue;

   6:  

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

   8:         //....        

   9:      }

  10: }    

 

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:

   1: //入口函数

   2: private IEnumerable<<YourEntity> GetAllNodes(XElement element)

   3: {

   4:     IList<YourEntity> ret = new List<YourEntity>();

   5:     

   6:     foreach (var elem in element.Elements())

   7:     {

   8:         if (elem.HasElements)

   9:         {

  10:             var node = CreateNode(elem);

  11:            

  12:             foreach (var item in CreateNodeCollection(elem)) // 这里面有递归

  13:             {

  14:                 node.Children.Add(item);

  15:             }

  16:             ret.Add(node);

  17:         }

  18:         else

  19:         {

  20:             ret.Add(CreateNode(elem));

  21:         }

  22:     

  23:     }        

  24:     return ret;     

  25: }

  26:  

  27: //递归调用

  28: private IEnumerable<YourEntity> CreateNodeCollection(XElement element)

  29: {

  30:     IList<YourEntity> ret = new List<YourEntity>();

  31:  

  32:     foreach (XElement elem in element.Elements())

  33:     {

  34:         if (elem.HasElements)

  35:         {

  36:             var node = CreateNode(elem);

  37:             foreach (var item in CreateNodeCollection(elem))

  38:             {

  39:                 node.Children.Add(item);

  40:             }

  41:             ret.Add(node);

  42:         }

  43:         else

  44:         {

  45:             ret.Add(CreateNode(elem, param));

  46:         }

  47:     }

  48:     return ret;

  49: }

  50:         

  51: private YourEntity CreateNode(XElement element)

  52: {

  53:     var ret = new YourEntity();

  54:     ret.Name = element.Name.ToString();

  55:     ret.Value = element.Value;

  56:     ret.Tag = element.HasAttributes ? element.FirstAttribute.Value : element.Value;

  57:     return ret;

  58: }                    

  59: