我正在使用iTextSharp库和C＃.Net来分割我的PDF文件。
考虑一个名为sample.pdf的PDF文件，其中包含72页。此sample.pdf包含具有导航到其他页面的超链接的页面。例如：在第4页中有三个超链接，当点击时导航到相应的第24,27,28页。与第4页一样，有近12页与它们有这个超链接。
现在使用iTextSharp库我已将此PDF页面拆分为72个单独的文件，并以1.pdf，2.pdf .... 72.pdf的名称保存。所以在4.pdf中点击超链接我需要让PDF导航到24.pdf，27.pdf，28.pdf。
请帮帮我。如何在4.pdf中编辑和设置超链接，以便导航到相应的pdf文件。
谢谢你， 阿肖克
答案 0 :(得分：6)
你想要的是完全可能的。你想要的是要求你使用低级PDF对象（PdfDictionary，PdfArray等）。
每当有人需要使用这些对象时，我总是将它们引用到PDF Reference。在您的情况下，您将要检查第7章（特别是第3节）和第12章，第3节（文档级导航）和第5章（注释）。
假设您已经阅读过，这就是您需要做的事情：
步骤1.1并不简单。有几种不同的“本地goto”注释格式。您需要确定给定链接指向的页面。某些链接可能表示PDF等效于“下一页”或“上一页”，而其他链接则包含对特定页面的引用。这将是“间接对象引用”，而不是页码。
要确定页面引用中的页码，您需要... ouch。好的。最有效的方法是为原始文档中的每个页面调用PdfReader.GetPageRef（int pageNum）并将其缓存在地图中（reference-＆gt; pageNum）。
然后，您可以通过创建远程goto PdfAction并将其写入链接注释的“A”（操作）条目来构建“远程goto”链接，删除之前存在的任何内容（可能是“Dest”）。
我不会很好地说C＃，所以我会把实际的实现留给你。
答案 1 :(得分：3)
好的，基于@Mark Storer这里的一些入门代码。第一种方法创建一个包含10个页面的示例PDF和第一页上的一些链接，这些链接会跳转到PDF的不同部分，因此我们可以使用。第二种方法打开在第一种方法中创建的PDF，并遍历每个注释，试图找出注释链接到哪个页面并将其输出到TRACE窗口。代码在VB中，但如果需要，应该很容易转换为C＃。它的目标是iTextSharp 5.1.1.0。
如果我有机会，我可能会尝试更进一步，实际上拆分并重新链接，但我现在没有时间。
Option Explicit On
Option Strict On
Imports iTextSharp.text
Imports iTextSharp.text.pdf
Imports System.IO
Public Class Form1
''//Folder that we are working in
Private Shared ReadOnly WorkingFolder As String = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "Hyperlinked PDFs")
''//Sample PDF
Private Shared ReadOnly BaseFile As String = Path.Combine(WorkingFolder, "Sample.pdf")
Private Shared Sub CreateSamplePdf()
''//Create our output directory if it does not exist
Directory.CreateDirectory(WorkingFolder)
''//Create our sample PDF
Using Doc As New iTextSharp.text.Document(PageSize.LETTER)
Using FS As New FileStream(BaseFile, FileMode.Create, FileAccess.Write, FileShare.Read)
Using writer = PdfWriter.GetInstance(Doc, FS)
Doc.Open()
''//Turn our hyperlinks blue
Dim BlueFont As Font = FontFactory.GetFont("Arial", 12, iTextSharp.text.Font.NORMAL, iTextSharp.text.BaseColor.BLUE)
''//Create 10 pages with simple labels on them
For I = 1 To 10
Doc.NewPage()
Doc.Add(New Paragraph(String.Format("Page {0}", I)))
''//On the first page add some links
If I = 1 Then
''//Go to pages relative to this page
Doc.Add(New Paragraph(New Chunk("First Page", BlueFont).SetAction(New PdfAction(PdfAction.FIRSTPAGE))))
Doc.Add(New Paragraph(New Chunk("Next Page", BlueFont).SetAction(New PdfAction(PdfAction.NEXTPAGE))))
Doc.Add(New Paragraph(New Chunk("Prev Page", BlueFont).SetAction(New PdfAction(PdfAction.PREVPAGE)))) ''//This one does not make sense but is here for completeness
Doc.Add(New Paragraph(New Chunk("Last Page", BlueFont).SetAction(New PdfAction(PdfAction.LASTPAGE))))
''//Go to a specific hard-coded page number
Doc.Add(New Paragraph(New Chunk("Go to page 5", BlueFont).SetAction(PdfAction.GotoLocalPage(5, New PdfDestination(0), writer))))
End If
Next
Doc.Close()
End Using
End Using
End Using
End Sub
Private Shared Sub ListPdfLinks()
''//Setup some variables to be used later
Dim R As PdfReader
Dim PageCount As Integer
Dim PageDictionary As PdfDictionary
Dim Annots As PdfArray
''//Open our reader
R = New PdfReader(BaseFile)
''//Get the page cont
PageCount = R.NumberOfPages
''//Loop through each page
For I = 1 To PageCount
''//Get the current page
PageDictionary = R.GetPageN(I)
''//Get all of the annotations for the current page
Annots = PageDictionary.GetAsArray(PdfName.ANNOTS)
''//Make sure we have something
If (Annots Is Nothing) OrElse (Annots.Length = 0) Then Continue For
''//Loop through each annotation
For Each A In Annots.ArrayList
''//I do not completely understand this but I think this turns an Indirect Reference into an actual object, but I could be wrong
''//Anyway, convert the itext-specific object as a generic PDF object
Dim AnnotationDictionary = DirectCast(PdfReader.GetPdfObject(A), PdfDictionary)
''//Make sure this annotation has a link
If Not AnnotationDictionary.Get(PdfName.SUBTYPE).Equals(PdfName.LINK) Then Continue For
''//Make sure this annotation has an ACTION
If AnnotationDictionary.Get(PdfName.A) Is Nothing Then Continue For
''//Get the ACTION for the current annotation
Dim AnnotationAction = DirectCast(AnnotationDictionary.Get(PdfName.A), PdfDictionary)
''//Test if it is a named actions such as /FIRST, /LAST, etc
If AnnotationAction.Get(PdfName.S).Equals(PdfName.NAMED) Then
Trace.Write("GOTO:")
If AnnotationAction.Get(PdfName.N).Equals(PdfName.FIRSTPAGE) Then
Trace.WriteLine(1)
ElseIf AnnotationAction.Get(PdfName.N).Equals(PdfName.NEXTPAGE) Then
Trace.WriteLine(Math.Min(I + 1, PageCount)) ''//Any links that go past the end of the document should just go to the last page
ElseIf AnnotationAction.Get(PdfName.N).Equals(PdfName.LASTPAGE) Then
Trace.WriteLine(PageCount)
ElseIf AnnotationAction.Get(PdfName.N).Equals(PdfName.PREVPAGE) Then
Trace.WriteLine(Math.Max(I - 1, 1)) ''//Any links the go before the first page should just go to the first page
End If
''//Otherwise see if its a GOTO page action
ElseIf AnnotationAction.Get(PdfName.S).Equals(PdfName.GOTO) Then
''//Make sure that it has a destination
If AnnotationAction.GetAsArray(PdfName.D) Is Nothing Then Continue For
''//Once again, not completely sure if this is the best route but the ACTION has a sub DESTINATION object that is an Indirect Reference.
''//The code below gets that IR, asks the PdfReader to convert it to an actual page and then loop through all of the pages
''//to see which page the IR points to. Very inneficient but I could not find a way to get the page number based on the IR.
''//AnnotationAction.GetAsArray(PdfName.D) gets the destination
''//AnnotationAction.GetAsArray(PdfName.D).ArrayList(0) get the indirect reference part of the destination (.ArrayList(1) has fitting options)
''//DirectCast(AnnotationAction.GetAsArray(PdfName.D).ArrayList(0), PRIndirectReference) turns it into a PRIndirectReference
''//The full line gets us an actual page object (actually I think it could be any type of pdf object but I have not tested that).
''//BIG NOTE: This line really should have a bunch more sanity checks in place
Dim AnnotationReferencedPage = PdfReader.GetPdfObject(DirectCast(AnnotationAction.GetAsArray(PdfName.D).ArrayList(0), PRIndirectReference))
Trace.Write("GOTO:")
''//Re-loop through all of the pages in the main document comparing them to this page
For J = 1 To PageCount
If AnnotationReferencedPage.Equals(R.GetPageN(J)) Then
Trace.WriteLine(J)
Exit For
End If
Next
End If
Next
Next
End Sub
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
CreateSamplePdf()
ListPdfLinks()
Me.Close()
End Sub
End Class
答案 2 :(得分：0)
以下此功能使用iTextSharp：
步骤＃4是在这里插入你想要的任何逻辑......更新链接，记录它们等等。
/// <summary>Inspects PDF files for internal links.
/// </summary>
public static void FindPdfDocsWithInternalLinks()
{
foreach (var fi in PdfFiles) {
try {
var reader = new PdfReader(fi.FullName);
// Pagination
for(var i = 1; i <= reader.NumberOfPages; i++) {
var pageDict = reader.GetPageN(i);
var annotArray = (PdfArray)PdfReader.GetPdfObject(pageDict.Get(PdfName.ANNOTS));
if (annotArray == null) continue;
if (annotArray.Length <= 0) continue;
// check every annotation on the page
foreach (var annot in annotArray.ArrayList) {
var annotDict = (PdfDictionary)PdfReader.GetPdfObject(annot);
if (annotDict == null) continue;
var subtype = annotDict.Get(PdfName.SUBTYPE).ToString();
if (subtype != "/Link") continue;
var linkDict = (PdfDictionary)annotDict.GetDirectObject(PdfName.A);
if (linkDict == null) continue;
// if it makes it this far, its an Anchor annotation
// so we can grab it's URI
var sUri = linkDict.Get(PdfName.URI).ToString();
if (String.IsNullOrEmpty(sUri)) continue;
}
}
reader.Close();
}
catch (InvalidPdfException e)
{
if (!fi.FullName.Contains("_vti_cnf"))
Console.WriteLine("\r\nInvalid PDF Exception\r\nFilename: " + fi.FullName + "\r\nException:\r\n" + e);
continue;
}
catch (NullReferenceException e)
{
if (!fi.FullName.Contains("_vti_cnf"))
Console.WriteLine("\r\nNull Reference Exception\r\nFilename: " + fi.Name + "\r\nException:\r\n" + e);
continue;
}
}
// DO WHATEVER YOU WANT HERE
}