C# GZipStream 突然无法正常工作

Question

我使用 GZipStream 有一段时间了，没有任何问题。我没有在我的函数中更改任何代码，但现在压缩和解压缩不起作用。我提取了以下简单的示例（也许我通常做错了什么......）。

public static class ZipLib
{
    #region Public Methods

    public static string Unzip(byte[] compressedText)
    {
        try {
            byte[] gzBuffer = compressedText;
            int msgLength = BitConverter.ToInt32(gzBuffer, 0);
            byte[] buffer = new byte[msgLength];
            using (MemoryStream ms = new MemoryStream()) {
                ms.Write(gzBuffer, 4, gzBuffer.Length - 4);

                using (GZipStream zip = new GZipStream(ms, CompressionMode.Decompress, true)) {
                    zip.Read(buffer, 0, buffer.Length);
                }
            }
            return Encoding.UTF8.GetString(buffer);
        }
        catch (Exception ex) {
            Debug.WriteLine(ex.Message);
        }
        return "";
    }

    public static byte[] Zip(string text)
    {
        byte[] buffer = Encoding.UTF8.GetBytes(text);
        MemoryStream ms = new MemoryStream();
        using (GZipStream zip = new GZipStream(ms, CompressionMode.Compress, true)) {
            zip.Write(buffer, 0, buffer.Length);
        }

        ms.Position = 0;

        byte[] compressed = new byte[ms.Length];
        ms.Read(compressed, 0, compressed.Length);

        byte[] gzBuffer = new byte[compressed.Length + 4];
        Buffer.BlockCopy(compressed, 0, gzBuffer, 4, compressed.Length);
        Buffer.BlockCopy(BitConverter.GetBytes(buffer.Length), 0, gzBuffer, 0, 4);

        return gzBuffer;
    }

    #endregion
}

internal class Program
{
    #region Private Methods

    private static void Main(string[] args)
    {
        string uncompressedIn = "Hallo Welt";
        var compressed = ZipLib.Zip(uncompressedIn);
        var uncompressed = ZipLib.Unzip(compressed);
        Console.WriteLine("Uncompressed Input: " + uncompressedIn);
        Console.WriteLine("Compressed value: " + string.Join(" | ", compressed));
        Console.WriteLine("Uncompressed from compressed: " + string.Join(" | ", uncompressed.ToCharArray()));
        Console.ReadKey();
    }

    #endregion
}

uncompressed 的值为"\0\0\0\0"...

Answer 1

在Unzip 中，您将Write 转换为MemoryStream，然后将其交给GZipStream 进行读取，但是：它仍在流的末尾，您没有倒带。尝试添加：

ms.Position = 0;

在Write 之后。但是请注意，这样做可能更有效：

using(MemoryStream ms = new MemoryStream(gzBuffer, 4, gzBuffer.Length - 4))
{
     //...
}

这样可以避免复制任何内存