这是一个处理数据解压缩,PKZIP压缩(sharpziplib)或GZip压缩(在. net创建)组件的基类。可能比你需要的功能多一点。这是一个使用@PhonicUK的建议来解析数据流的头的例子。你看到的工厂方法中的派生类是用来处理PKZip和GZip解压缩的细节。

abstract class Expander
{
    private const int ZIP_LEAD_BYTES = 0x04034b50;
    private const ushort GZIP_LEAD_BYTES = 0x8b1f;
    public abstract MemoryStream Expand(Stream stream); 
    internal static bool IsPkZipCompressedData(byte[] data)
    {
        Debug.Assert(data != null && data.Length >= 4);
        // if the first 4 bytes of the array are the ZIP signature then it is compressed data
        return (BitConverter.ToInt32(data, 0) == ZIP_LEAD_BYTES);
    }
    internal static bool IsGZipCompressedData(byte[] data)
    {
        Debug.Assert(data != null && data.Length >= 2);
        // if the first 2 bytes of the array are theG ZIP signature then it is compressed data;
        return (BitConverter.ToUInt16(data, 0) == GZIP_LEAD_BYTES);
    }
    public static bool IsCompressedData(byte[] data)
    {
        return IsPkZipCompressedData(data) || IsGZipCompressedData(data);
    }
    public static Expander GetExpander(Stream stream)
    {
        Debug.Assert(stream != null);
        Debug.Assert(stream.CanSeek);
        stream.Seek(0, 0);
        try
        {
            byte[] bytes = new byte[4];
            stream.Read(bytes, 0, 4);
            if (IsGZipCompressedData(bytes))
                return new GZipExpander();
            if (IsPkZipCompressedData(bytes))
                return new ZipExpander();
            return new NullExpander();
        }
        finally
        {
            stream.Seek(0, 0);  // set the stream back to the begining
        }
    }
}

你也可以这样:

• 使用try – catch结构并试图读取一个潜在的zip文件的结构

• 解析文件头,看看这是不是一个zip文件

ZIP文件总是从0x04034b50开始作为它的前4个字节( http://en.wikipedia.org/wiki/Zip_(file_format)#File_headers )

参考http://stackoverflow.com/a/16587134/206730 链接
参考下面链接:
icsharpcode-sharpziplib-validate-zip-file
How-to-check-if-a-file-is-compressed-in-c#
ZIP文件总是从0x04034b50开始(4 bytes)查看更多: http://en.wikipedia.org/wiki/Zip_(file_format)#File_headers
使用例子:

        bool isPKZip = IOHelper.CheckSignature(pkg, 4, IOHelper.SignatureZip);
        Assert.IsTrue(isPKZip, "Not ZIP the package : " + pkg);
// http://blog.somecreativity.com/2008/04/08/how-to-check-if-a-file-is-compressed-in-c/
    public static partial class IOHelper
    {
        public const string SignatureGzip = "1F-8B-08";
        public const string SignatureZip = "50-4B-03-04";
        public static bool CheckSignature(string filepath, int signatureSize, string expectedSignature)
        {
            if (String.IsNullOrEmpty(filepath)) throw new ArgumentException("Must specify a filepath");
            if (String.IsNullOrEmpty(expectedSignature)) throw new ArgumentException("Must specify a value for the expected file signature");
            using (FileStream fs = new FileStream(filepath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
            {
                if (fs.Length < signatureSize)
                    return false;
                byte[] signature = new byte[signatureSize];
                int bytesRequired = signatureSize;
                int index = 0;
                while (bytesRequired > 0)
                {
                    int bytesRead = fs.Read(signature, index, bytesRequired);
                    bytesRequired -= bytesRead;
                    index += bytesRead;
                }
                string actualSignature = BitConverter.ToString(signature);
                if (actualSignature == expectedSignature) return true;
                return false;
            }
        }
    }

如果你是web网络编程,你可以检查文件Content Type: application/zip