GZipStream和解压

Question

我有应该做压缩的代码：

FileStream fs = new FileStream("g:\\gj.txt", FileMode.Open);
FileStream fd = new FileStream("g:\\gj.zip", FileMode.Create);
GZipStream csStream = new GZipStream(fd, CompressionMode.Compress);

byte[] compressedBuffer = new byte[500];
int offset = 0;
int nRead;

nRead = fs.Read(compressedBuffer, offset, compressedBuffer.Length);
while (nRead > 0)
{
    csStream.Write(compressedBuffer, offset, nRead);
    offset = offset + nRead;
    nRead = fs.Read(compressedBuffer, offset, compressedBuffer.Length);
}

fd.Close();
fs.Close();

我认为是这样的，但我想要解压上面压缩的内容。我确实是这么想的：

FileStream fd = new FileStream("g:\\gj.new", FileMode.Create);
FileStream fs = new FileStream("g:\\gj.zip", FileMode.Open);
GZipStream csStream = new GZipStream(fs, CompressionMode.Decompress);

byte[] decompressedBuffer = new byte[500];
int offset = 0;
int nRead;

nRead=csStream.Read(decompressedBuffer, offset, decompressedBuffer.Length);
while (nRead > 0)
{
    fd.Write(decompressedBuffer, offset, nRead);
    offset = offset + nRead;
    nRead = csStream.Read(decompressedBuffer, offset, decompressedBuffer.Length);
}

fd.Close();
fs.Close();

在这里它没有..。在进入循环之前，我已经得到了nRead =0...我做错了什么？？我使用的测试文件是最简单的文本文件(大小: 104字节)...

Answer 1

我的第一个想法是你还没有关闭csStream。如果你使用using，这会自动发生。由于gzip对数据进行缓冲，因此可能会丢失一些数据。

其次，不要递增offset；这是缓冲区(而不是流)中的偏移量。离开时间为0：

using (Stream fs = File.OpenRead("gj.txt"))
using (Stream fd = File.Create("gj.zip"))
using (Stream csStream = new GZipStream(fd, CompressionMode.Compress))
{
    byte[] buffer = new byte[1024];
    int nRead;
    while ((nRead = fs.Read(buffer, 0, buffer.Length))> 0)
    {
        csStream.Write(buffer, 0, nRead);
    }
}

using (Stream fd = File.Create("gj.new.txt"))
using (Stream fs = File.OpenRead("gj.zip"))
using (Stream csStream = new GZipStream(fs, CompressionMode.Decompress))
{
    byte[] buffer = new byte[1024];
    int nRead;
    while ((nRead = csStream.Read(buffer, 0, buffer.Length)) > 0)
    {
        fd.Write(buffer, 0, nRead);
    }
}

Answer 2

我有两个方法，就像James Roland提到的那样。

private static byte[] Compress(HttpPostedFileBase file)
{
    using var to = new MemoryStream();
    using var gZipStream = new GZipStream(to, CompressionMode.Compress);
    file.InputStream.CopyTo(gZipStream);
    gZipStream.Flush();
    return to.ToArray();
}

private static byte[] Decompress(byte[] compressed)
{
    using var from = new MemoryStream(compressed);
    using var to = new MemoryStream();
    using var gZipStream = new GZipStream(from, CompressionMode.Decompress);
    gZipStream.CopyTo(to);
    return to.ToArray();
}

但是，我使用的是upload

Request.Files[0] 

然后压缩并保存在数据库中。然后我把img拉出来，解压缩并设置src

$"data:image/gif;base64,{ToBase64String(Decompress(img))}";