使用iText 7获取PDF文件的创建日期 [英] Get the Creation Date of a PDF file using iText 7

问题描述

我必须创建一个工具，该工具会将其创建日期添加到多个.pdf文件名中. 我想使用内部存储在pdfs中的creationdate，为此，我下载了iText Community Edition.

I have to create a tool which adds to several .pdf file names their creation date. I'd like to use the creationdate stored internally in pdfs and for this I downloaded iText Community Edition.

现在，我的代码以(VB)开头

Now, my code starts like this (VB)

Module Module1

    Sub Main()

        Dim filename As String = My.Application.CommandLineArgs(0)

        Dim PDFReader = New Pdf.PdfReader(filename)
        Dim PDFDocument = New Pdf.PdfDocument(PDFReader)

        Dim documentinfo As Pdf.PdfDocumentInfo = PDFDocument.GetDocumentInfo

        Dim author As String = documentinfo.GetAuthor
        Dim creator As String = documentinfo.GetCreator
        Dim mypdfobject = documentinfo.GetPdfObject

    End Sub

End Module

我获得了GetAuthor和GetCreator以及其他几个Get方法，但是找不到诸如GetCreationDate之类的东西，只有AddCreationDate.

I got the GetAuthor and GetCreator together with several other Get method, but I can't find something like GetCreationDate, only AddCreationDate.

如果我进一步进入mypdfobject，则会在映射中找到一个/Creationdate标记，因此我想使用该标记，但是尽管它通常采用D:20160704132234 + 02'00'格式，但有时我会发现一些看起来像二进制的东西数据，我不知道如何解码.

If I go further into mypdfobject I find into map a /Creationdate tag, so I thought to use that, but, while it is often in the format D:20160704132234+02'00', sometimes I find something which seems binary data and I don't know how to decode that.

是否有更好的方法来获取创建日期?

Is there any better way to get the creation date ?

谢谢

Stefano

推荐答案

创建日期是PDF字符串值.有两种表示字符串的方法.您已经知道这种方式:(D:20160704132234+02'00')，但是还有一个十六进制表示法，例如:<443A32303136303730343133323233342b303227303027>.

The creation date is a PDF string value. There are two ways to represent a string. You already know this way: (D:20160704132234+02'00'), but there's also a hexadecimal notation, for instance: <443A32303136303730343133323233342b303227303027>.

拥有PdfString时，可以通过不同的方式获取值:有toString()，但也有toUnicodeString().如果您使用的是String版本，则可以从PdfDate类中获取一个Calendar对象:

When you have a PdfString, you can get the value in different ways: there's toString(), but there's also toUnicodeString(). When you have a String version, you can get a Calendar object from the PdfDate class:

Calendar date = PdfDate.decode(s);

如果您希望使用W3C格式的日期，则可以执行以下操作:

If you want the date in W3C format, you can do something like this:

string w3cDate = PdfDate.getW3CDate(s);

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