如何使用C#检查文件是有效的XPS文件? [英] How Can I Check That A File Is A Valid XPS File With C#?

问题描述

我有一个处理XPS文件的WinForms应用程序.如何使用C#检查用户在打开的对话框中选择的文件是有效的XPS文件?

I have a WinForms application that processes XPS files. How can I check that the file the user has selected in the open dialog is a valid XPS file using C#?

将存在带有.XPS扩展名的文件，这些文件不是真正的XPS文件.

There WILL be files present with the .XPS extension that are not really XPS files.

由于XPS文件实际上是PKZIP格式，因此我可以检查PKZIP字节签名，但这会给ZIP存档带来误报.

Since XPS files are really in the PKZIP format, I could check for the PKZIP byte signature but that would give false positives on ZIP archives.

推荐答案

以下内容将XPS文件与其他ZIP存档和非ZIP文件区分开.它不会确定该文件是否为完全有效的XPS-为此，您将需要加载每个页面.

The following will distinguish XPS files from other ZIP archives and non-ZIP files. It won't determine whether the file is fully-valid XPS - for that you would need to load each page.

using System;
using System.IO;
using System.Windows.Xps.Packaging;

class Tester
{
    public static bool IsXps(string filename)
    {
        try
        {
            XpsDocument x = new XpsDocument(filename, FileAccess.Read);

            IXpsFixedDocumentSequenceReader fdsr = x.FixedDocumentSequenceReader;

            // Needed to actually try to find the FixedDocumentSequence
            Uri uri = fdsr.Uri;

            return true;
        }
        catch (Exception)
        {
        }

        return false;
    }
}

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