我遇到在.NET 4.0中的一些奇怪的机器/ OS依赖GZipStream行为。这是相关的code：

 公共静态字符串的COM preSS（字符串输入）{
    使用（VAR毫秒=新的MemoryStream（Encoding.UTF8.GetBytes（输入）））
    使用（VAR OS =新的MemoryStream（））{
        使用（VAR GZ =新GZipStream（OS，COM pressionMode.Com preSS，真））{
            ms.CopyTo（GZ）;
        }
        返回的string.join（，os.ToArray（）选择（二=＆GT; b.T​​oString（X2）））;
    }
}
 

正在运行的COM preSS（FREEK）给了我

  1F8B08000000000004004B2B4A4DCD06001E33909D05000000
 

在Windows 7和

1F8B0800000000000400ECBD07601C499625262F6DCA7B7F4AF54AD7E074A10880601324D8904010ECC188CDE692EC1D69472329AB2A81CA6556655D661640CCED9DBCF7DE7BEFBDF7DE7BEFBDF7BA3B9D4E27F7DFFF3F5C6664016CF6CE4ADAC99E2180AAC81F3F7E7C1F3F22CEEB3C7FFBFF040000FFFF1E33909D05000000

在基于Windows Server 2008R2。两者都是64位。我期望的结果是相同的。

这两款机器给出正确的结果，当我DECOM preSS无论是结果。我已经发现，在W7 ms.Length == 25，而在W2K8R2 ms.Length == 128，但不知道为什么。

这是怎么回事？

解决方案

It会上宣布，.NET 4.5 Beta版，包括拉链COM pression改进，以减少大小：

  

从.NET Framework 4.5 RC开始，DeflateStream类使用的COM pression zlib库。其结果是，它提供了一个更好的COM pression算法，在大多数情况下，一个较小的COM pressed文件比它提供了在早期版本的.NET Framework

你也许有净4.5+安装Win7的机器上？

I'm running into some strange machine/OS dependent GZipStream behavior in .NET 4.0. This is the relevant code:

public static string Compress(string input) {
    using(var ms = new MemoryStream(Encoding.UTF8.GetBytes(input)))
    using(var os = new MemoryStream()) {
        using(var gz = new GZipStream(os,CompressionMode.Compress,true)) {
            ms.CopyTo(gz);
        }
        return string.Join("",os.ToArray().Select(b=>b.ToString("X2")));
    }
}

Running Compress("freek") gives me

1F8B08000000000004004B2B4A4DCD06001E33909D05000000

on Windows 7 and

1F8B0800000000000400ECBD07601C499625262F6DCA7B7F4AF54AD7E074A10880601324D8904010ECC188CDE692EC1D69472329AB2A81CA6556655D661640CCED9DBCF7DE7BEFBDF7DE7BEFBDF7BA3B9D4E27F7DFFF3F5C6664016CF6CE4ADAC99E2180AAC81F3F7E7C1F3F22CEEB3C7FFBFF040000FFFF1E33909D05000000

on Windows Server 2008R2. Both are 64bit. I would expect the results to be the same.

Both machines give the correct result when I decompress either result. I already found out that on W7 ms.Length == 25 while on W2K8R2 ms.Length==128, but no clue why.

What's going on?

解决方案

It was announced that .NET 4.5 Beta includes zip compression improvements to reduce the size:

Starting with the .NET Framework 4.5 RC, the DeflateStream class uses the zlib library for compression. As a result, it provides a better compression algorithm and, in most cases, a smaller compressed file than it provides in earlier versions of the .NET Framework.

Do you perhaps have .Net 4.5+ installed on the Win7 machine?