如何从字节数组创建XpsDocument？

Question

我想从字节数组创建一个新的System.Windows.Xps.Packaging.XpsDocument对象,因为我不想立即将它存储在本地计算机上.

通过使用临时文件,它工作正常:

public static XpsDocument OpenXpsDocument(string url)
{
    WebClient webClient = new System.Net.WebClient();
    byte[] data = webClient.DownloadData(url);

    using (BinaryWriter writer = new System.IO.BinaryWriter(File.OpenWrite(xpsTempFilePath)))
    {
        writer.Write(data);
        writer.Flush();
    }

    XpsDocument xpsDocument = new System.Windows.Xps.Packaging.XpsDocument(xpsTempFilePath, FileAccess.Read);
    return xpsDocument;
}

但是,我想要完成的更像是这样的:

public static XpsDocument OpenXpsDocument(string url)
{
    WebClient webClient = new WebClient();
    byte[] data = webClient.DownloadData(url);
    Package package;
    using (Stream stream = new MemoryStream(data))
    {
        package = System.IO.Packaging.Package.Open(stream);
    }
    XpsDocument xpsDocument = new XpsDocument(package, CompressionOption.SuperFast, url);
    return xpsDocument;
}

上述方法的用法如下:

XpsDocument xps = TaxReturnCreator.OpenXpsDocument(tempFileUrl);
documentViewer1.Document = xps.GetFixedDocumentSequence();

并且,使用最后描述的尝试在WPF窗口中显示XPS内容的方法(不保存)与System.ObjectDisposedException("无法访问已关闭的流")崩溃(第一种方法正常).

在创建XpsDocument之后我还是应该保持Stream打开,还是我错过了其他的东西？也许有人知道一种完全不同/更好的方法,通过网络检索XPS数据作为字节,并从数据创建XpsDocument对象？

Answer 1

您无法关闭支持XpsDocument的流.您必须允许Package管理后备MemoryStream,这将在收集此Package后收集.执行以下操作可能看起来有些异端:

public static XpsDocument OpenXpsDocument(string url)
{
    var webClient = new WebClient();
    var data = webClient.DownloadData(url);
    var package = System.IO.Packaging.Package.Open(new MemoryStream(data));
    var xpsDocument = new XpsDocument(package, 
                                      CompressionOption.SuperFast, 
                                      url);
    return xpsDocument;
}

但这是必须如何做到的.