对不同形状的 XML 进行投影
本主题演示对形状不同于源 XML 的 XML 进行投影的示例。
许多典型的 XML 转换由链接的查询组成，如本示例中所示。 一种很常见的做法是从某种格式的 XML 开始，将中间结果投影为匿名类型或命名类型的集合，最后将结果投影回与源 XML 形状完全不同的 XML。
示例
本示例处理一个 WordprocessingML 文档，它从 WordprocessingML 文档中检索段落节点。 本示例还标识每个段落的样式和文本。 最后，本示例将以不同的形状投影 XML。 本示例以本教程中前面的一些示例为基础构建。 下面代码中的注释标识出了执行投影操作的新语句。
有关创建本示例的源文档的说明，请参见创建源 Office Open XML 文档。
本示例使用 WindowsBase 程序集中的类。 它使用 System.IO.Packaging 命名空间中的类型。
public static class LocalExtensions
{
public static string StringConcatenate(this IEnumerable<string> source)
{
StringBuilder sb = new StringBuilder();
foreach (string s in source)
sb.Append(s);
return sb.ToString();
}
public static string StringConcatenate<T>(this IEnumerable<T> source,
Func<T, string> func)
{
StringBuilder sb = new StringBuilder();
foreach (T item in source)
sb.Append(func(item));
return sb.ToString();
}
public static string StringConcatenate(this IEnumerable<string> source, string separator)
{
StringBuilder sb = new StringBuilder();
foreach (string s in source)
sb.Append(s).Append(separator);
return sb.ToString();
}
public static string StringConcatenate<T>(this IEnumerable<T> source,
Func<T, string> func, string separator)
{
StringBuilder sb = new StringBuilder();
foreach (T item in source)
sb.Append(func(item)).Append(separator);
return sb.ToString();
}
}
class Program
{
public static string ParagraphText(XElement e)
{
XNamespace w = e.Name.Namespace;
return e
.Elements(w + "r")
.Elements(w + "t")
.StringConcatenate(element => (string)element);
}
static void Main(string[] args)
{
const string fileName = "SampleDoc.docx";
const string documentRelationshipType =
"https://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument";
const string stylesRelationshipType =
"https://schemas.openxmlformats.org/officeDocument/2006/relationships/styles";
const string wordmlNamespace =
"https://schemas.openxmlformats.org/wordprocessingml/2006/main";
XNamespace w = wordmlNamespace;
XDocument xDoc = null;
XDocument styleDoc = null;
using (Package wdPackage = Package.Open(fileName, FileMode.Open, FileAccess.Read))
{
PackageRelationship docPackageRelationship =
wdPackage.GetRelationshipsByType(documentRelationshipType).FirstOrDefault();
if (docPackageRelationship != null)
{
Uri documentUri = PackUriHelper.ResolvePartUri(new Uri("/", UriKind.Relative),
docPackageRelationship.TargetUri);
PackagePart documentPart = wdPackage.GetPart(documentUri);
// Load the document XML in the part into an XDocument instance.
xDoc = XDocument.Load(XmlReader.Create(documentPart.GetStream()));
// Find the styles part. There will only be one.
PackageRelationship styleRelation =
documentPart.GetRelationshipsByType(stylesRelationshipType).FirstOrDefault();
if (styleRelation != null)
{
Uri styleUri =
PackUriHelper.ResolvePartUri(documentUri, styleRelation.TargetUri);
PackagePart stylePart = wdPackage.GetPart(styleUri);
// Load the style XML in the part into an XDocument instance.
styleDoc = XDocument.Load(XmlReader.Create(stylePart.GetStream()));
}
}
}
string defaultStyle =
(string)(
from style in styleDoc.Root.Elements(w + "style")
where (string)style.Attribute(w + "type") == "paragraph" &&
(string)style.Attribute(w + "default") == "1"
select style
).First().Attribute(w + "styleId");
// Find all paragraphs in the document.
var paragraphs =
from para in xDoc
.Root
.Element(w + "body")
.Descendants(w + "p")
let styleNode = para
.Elements(w + "pPr")
.Elements(w + "pStyle")
.FirstOrDefault()
select new
{
ParagraphNode = para,
StyleName = styleNode != null ?
(string)styleNode.Attribute(w + "val") :
defaultStyle
};
// Retrieve the text of each paragraph.
var paraWithText =
from para in paragraphs
select new
{
ParagraphNode = para.ParagraphNode,
StyleName = para.StyleName,
Text = ParagraphText(para.ParagraphNode)
};
// The following is the new code that projects XML in a new shape.
XElement root = new XElement("Root",
from p in paraWithText
select new XElement("Paragraph",
new XElement("StyleName", p.StyleName),
new XElement("Text", p.Text)
)
);
Console.WriteLine(root);
}
}
Imports <xmlns:w="https://schemas.openxmlformats.org/wordprocessingml/2006/main">
Module Module1
<System.Runtime.CompilerServices.Extension()> _
Public Function StringConcatenate(ByVal source As IEnumerable(Of String)) As String
Dim sb As StringBuilder = New StringBuilder()
For Each s As String In source
sb.Append(s)
Next
Return sb.ToString()
End Function
<System.Runtime.CompilerServices.Extension()> _
Public Function StringConcatenate(Of T)(ByVal source As IEnumerable(Of T), _
ByVal func As Func(Of T, String)) As String
Dim sb As StringBuilder = New StringBuilder()
For Each item As T In source
sb.Append(func(item))
Next
Return sb.ToString()
End Function
<System.Runtime.CompilerServices.Extension()> _
Public Function StringConcatenate(Of T)(ByVal source As IEnumerable(Of T), _
ByVal separator As String) As String
Dim sb As StringBuilder = New StringBuilder()
For Each s As T In source
sb.Append(s).Append(separator)
Next
Return sb.ToString()
End Function
<System.Runtime.CompilerServices.Extension()> _
Public Function StringConcatenate(Of T)(ByVal source As IEnumerable(Of T), _
ByVal func As Func(Of T, String), ByVal separator As String) As String
Dim sb As StringBuilder = New StringBuilder()
For Each item As T In source
sb.Append(func(item)).Append(separator)
Next
Return sb.ToString()
End Function
Public Function ParagraphText(ByVal e As XElement) As String
Dim w As XNamespace = e.Name.Namespace
Return (e.<w:r>.<w:t>).StringConcatenate(Function(element) CStr(element))
End Function
' Following function is required because VB does not support short circuit evaluation
Private Function GetStyleOfParagraph(ByVal styleNode As XElement, _
ByVal defaultStyle As String) As String
If (styleNode Is Nothing) Then
Return defaultStyle
Else
Return styleNode.@w:val
End If
End Function
Sub Main()
Dim fileName = "SampleDoc.docx"
Dim documentRelationshipType = _
"https://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument"
Dim stylesRelationshipType = _
"https://schemas.openxmlformats.org/officeDocument/2006/relationships/styles"
Dim wordmlNamespace = _
"https://schemas.openxmlformats.org/wordprocessingml/2006/main"
Dim xDoc As XDocument = Nothing
Dim styleDoc As XDocument = Nothing
Using wdPackage As Package = Package.Open(fileName, FileMode.Open, FileAccess.Read)
Dim docPackageRelationship As PackageRelationship = _
wdPackage.GetRelationshipsByType(documentRelationshipType).FirstOrDefault()
If (docPackageRelationship IsNot Nothing) Then
Dim documentUri As Uri = PackUriHelper.ResolvePartUri(New Uri("/", UriKind.Relative), _
docPackageRelationship.TargetUri)
Dim documentPart As PackagePart = wdPackage.GetPart(documentUri)
' Load the document XML in the part into an XDocument instance.
xDoc = XDocument.Load(XmlReader.Create(documentPart.GetStream()))
' Find the styles part. There will only be one.
Dim styleRelation As PackageRelationship = _
documentPart.GetRelationshipsByType(stylesRelationshipType).FirstOrDefault()
If (Not (styleRelation Is Nothing)) Then
Dim styleUri As Uri = _
PackUriHelper.ResolvePartUri(documentUri, styleRelation.TargetUri)
Dim stylePart As PackagePart = wdPackage.GetPart(styleUri)
' Load the style XML in the part into an XDocument instance.
styleDoc = XDocument.Load(XmlReader.Create(stylePart.GetStream()))
End If
End If
End Using
Dim defaultStyle As String = _
( _
From style In styleDoc.Root.<w:style> _
Where style.@w:type = "paragraph" And _
style.@w:default = "1" _
Select style _
).First().@w:styleId
' Find all paragraphs in the document.
Dim paragraphs = _
From para In xDoc.Root.<w:body>...<w:p> _
Let styleNode As XElement = para.<w:pPr>.<w:pStyle>.FirstOrDefault _
Select New With { _
.ParagraphNode = para, _
.StyleName = GetStyleOfParagraph(styleNode, defaultStyle) _
}
' Retrieve the text of each paragraph.
Dim paraWithText = _
From para In paragraphs _
Select New With { _
.ParagraphNode = para.ParagraphNode, _
.StyleName = para.StyleName, _
.Text = ParagraphText(para.ParagraphNode) _
}
' Following is the new code that projects XML in a new shape
Dim root As XElement = _
<Root>
<%= _
From p In paraWithText _
Select _
<Paragraph>
<StyleName><%= p.StyleName %></StyleName>
<Text><%= p.Text %></Text>
</Paragraph> _
%>
</Root>
Console.WriteLine(root)
End Sub
End Module
此示例产生以下输出：
<Root>
<Paragraph>
<StyleName>Heading1</StyleName>
<Text>Parsing WordprocessingML with LINQ to XML</Text>
</Paragraph>
<Paragraph>
<StyleName>Normal</StyleName>
<Text></Text>
</Paragraph>
<Paragraph>
<StyleName>Normal</StyleName>
<Text>The following example prints to the console.</Text>
</Paragraph>
<Paragraph>
<StyleName>Normal</StyleName>
<Text></Text>
</Paragraph>
<Paragraph>
<StyleName>Code</StyleName>
<Text>using System;</Text>
</Paragraph>
<Paragraph>
<StyleName>Code</StyleName>
<Text></Text>
</Paragraph>
<Paragraph>
<StyleName>Code</StyleName>
<Text>class Program {</Text>
</Paragraph>
<Paragraph>
<StyleName>Code</StyleName>
<Text> public static void (string[] args) {</Text>
</Paragraph>
<Paragraph>
<StyleName>Code</StyleName>
<Text> Console.WriteLine("Hello World");</Text>
</Paragraph>
<Paragraph>
<StyleName>Code</StyleName>
<Text> }</Text>
</Paragraph>
<Paragraph>
<StyleName>Code</StyleName>
<Text>}</Text>
</Paragraph>
<Paragraph>
<StyleName>Normal</StyleName>
<Text></Text>
</Paragraph>
<Paragraph>
<StyleName>Normal</StyleName>
<Text>This example produces the following output:</Text>
</Paragraph>
<Paragraph>
<StyleName>Normal</StyleName>
<Text></Text>
</Paragraph>
<Paragraph>
<StyleName>Code</StyleName>
<Text>Hello World</Text>
</Paragraph>
</Root>
后续步骤
下面的示例将通过查询查找 Word 文档中的所有文本：