DotNetZip 失败并出现"stream does not support seek operations"

Question

我在C#中使用DotNetZip从流中解压缩，如下所示：

public static void unzipFromStream(Stream stream, string outdir)
{   //omit try catch block
    using (ZipFile zip = ZipFile.Read(stream)){
        foreach (ZipEntry e in zip){
            e.Extract(outdir, ExtractExistingFileAction.OverwriteSilently);
        }
    }
}

使用获得流

WebClient client = new WebClient();
Stream fs = client.OpenRead(url);

然而，我得到了以下异常

exception during extracting zip from stream System.NotSupportedException: This stream does not support seek operations.
at System.Net.ConnectStream.get_Position()
at Ionic.Zip.ZipFile.Read(Stream zipStream, TextWriter statusMessageWriter, Encoding encoding, EventHandler`1 readProgress)

在服务器端（ASP.NET MVC 4），返回FilePathResult或FileStreamResult都会导致此异常。

我应该在客户端以不同的方式获取流吗？或者如何让服务器返回一个"可查找"的流？谢谢

Answer 1

您必须将数据下载到文件或内存中，然后创建FileStream或MemoryStream，或其他支持查找的流类型。例如：

WebClient client = new WebClient();
client.DownloadFile(url, filename);
using (var fs = File.OpenRead(filename))
{
    unzipFromStream(fs, outdir);
}
File.Delete(filename);

或者，如果数据适合内存：

byte[] data = client.DownloadData(url);
using (var fs = new MemoryStream(data))
{
    unzipFromStream(fs, outdir);
}