DeflateStream CopyTo MemoryStream

Question

需要压缩和解压缩MemoryStream，但是CopyTo似乎不像预期的那样工作吗？为什么？怎么解决这个问题？

public static MemoryStream Compress(MemoryStream originalStream)
{
    Console.WriteLine("Original before compressing size: {0}", originalStream.Length.ToString());
    MemoryStream compressedMemoryStream = new MemoryStream();

    using (DeflateStream deflateStream = new DeflateStream(compressedMemoryStream, CompressionMode.Compress, true))
    {
        originalStream.CopyTo(deflateStream);
    }
    Console.WriteLine("Compressed size: {0}", compressedMemoryStream.Length.ToString());
    return compressedMemoryStream;
}

public static void Decompress(MemoryStream compressedStream)
{
    Console.WriteLine("Compressed before decompressing size: {0}", compressedStream.Length.ToString());
    using (MemoryStream decompressedFileStream = new MemoryStream())
    {
         using (DeflateStream decompressionStream = new DeflateStream(compressedStream, CompressionMode.Decompress, true))
         {
              decompressionStream.CopyTo(decompressedFileStream);
         }
         Console.WriteLine("Decompressed size: {0}", decompressedFileStream.Length.ToString());
    }
}

输出：

Original before compressing size: 5184054
Compressed size: 0
Compressed before decompressing size: 0
Decompressed size: 0

Answer 1

CopyTo开始从源流的当前位置复制字节。

由于您发布的压缩流大小为0，所以我确信originalStream位于流的末尾，因此没有复制/压缩字节。

确保位置是0，这样它就可以找到要复制和压缩到流中的任何数据。

正如@xanatos所提到的，同样的情况也适用于Decompress，所以在解压缩它之前，请确保compressedStream也位于0。