检索段落的文本
此示例以上一个示例检索段落及其样式为基础。这个新示例将每个段落的文本作为字符串进行检索。
为检索文本，此示例另外添加了一个查询，该查询循环访问匿名类型的集合，并通过添加新成员 Text 对一个匿名类型的新集合进行投影。该示例使用 Aggregate 标准查询运算符将多个字符串串联为一个字符串。
这种方法（即首先投影到一个匿名类型集合，然后使用该集合投影到一个新的匿名类型集合）是一种既常用又有效的方法。此查询在编写时本来可以不投影到第一个匿名类型。但是因为使用迟缓计算，即使这样做也并不会过多占用额外的处理能力。此方法在堆上创建更多生存时间很短的对象，但这并不会显著降低性能。
当然，可以只编写一个查询，使之包含检索段落、每个段落的样式以及每个段落的文本这些功能。但是，将一个比较复杂的查询分解成多个查询通常很有好处，因为这样产生的代码更加模块化，更易于维护。而且，如果需要重用查询的某一部分，使用此方式编写的查询更容易重构。
这些链接在一起的查询使用的处理模型在教程：将查询链接在一起主题中有详细的讨论。
示例
本示例处理一个 WordprocessingML 文档，它确定元素节点、样式名称和每个段落的文本。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这个新查询。
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。
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
};
// Following is the new query that retrieves the text of
// each paragraph.
var paraWithText =
from para in paragraphs
select new
{
ParagraphNode = para.ParagraphNode,
StyleName = para.StyleName,
Text = para
.ParagraphNode
.Elements(w + "r")
.Elements(w + "t")
.Aggregate(
new StringBuilder(),
(s, i) => s.Append((string)i),
s => s.ToString()
)
};
foreach (var p in paraWithText)
Console.WriteLine("StyleName:{0} >{1}<", p.StyleName, p.Text);
Imports <xmlns:w="https://schemas.openxmlformats.org/wordprocessingml/2006/main">
Module Module1
' 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 (styleRelation IsNot 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) _
}
' Following is the new query that retrieves the text of
' each paragraph.
Dim paraWithText = _
From para In paragraphs _
Select New With { _
.ParagraphNode = para.ParagraphNode, _
.StyleName = para.StyleName, _
.Text = para.ParagraphNode.<w:r>.<w:t> _
.Aggregate(New StringBuilder(), _
Function(s As StringBuilder, i As String) s.Append(CStr(i)), _
Function(s As StringBuilder) s.ToString) _
}
For Each p In paraWithText
Console.WriteLine("StyleName:{0} >{1}<", p.StyleName, p.Text)
Next
End Sub
End Module
当此示例应用于创建源 Office Open XML 文档中说明的文档时，会生成以下输出。
StyleName:Heading1 >Parsing WordprocessingML with LINQ to XML<
StyleName:Normal ><
StyleName:Normal >The following example prints to the console.<
StyleName:Normal ><
StyleName:Code >using System;<
StyleName:Code ><
StyleName:Code >class Program {<
StyleName:Code > public static void (string[] args) {<
StyleName:Code > Console.WriteLine("Hello World");<
StyleName:Code > }<
StyleName:Code >}<
StyleName:Normal ><
StyleName:Normal >This example produces the following output:<
StyleName:Normal ><
StyleName:Code >Hello World<
后续步骤
下面的示例演示如何使用扩展方法而不是 Aggregate 将多个字符串串联为一个字符串。