c# - DeflateStream在MemoryStream上不起作用吗？

我有以下代码:

MemoryStream resultStream = new MemoryStream();
string users = ""//Really long string goes here
BinaryFormatter bFormatter = new BinaryFormatter();
using (MemoryStream assignedUsersStream = new MemoryStream())
{
    bFormatter.Serialize(assignedUsersStream, users);
    assignedUsersStream.Position = 0;

    using (var compressionStream =
        new DeflateStream(resultStream, CompressionLevel.Optimal))
    {
        assignedUsersStream.CopyTo(compressionStream);

        Console.WriteLine("Compressed from {0} to {1} bytes.",
            assignedUsersStream.Length.ToString(),
            resultStream.Length.ToString());
    }
}

事实是resultStream始终为空!

我在这里做错了什么？

最佳答案

将您的验证WriteLine置于使用范围之外。缓冲区尚未刷新。

using (DeflateStream compressionStream = new DeflateStream(resultStream, CompressionLevel.Optimal))
{
    assignedUsersStream.CopyTo(compressionStream);

    //Console.WriteLine("Compressed from {0} to {1} bytes.",
    //       assignedUsersStream.Length.ToString(), resultStream.Length.ToString());
}

Console.WriteLine("Compressed from {0} to {1} bytes.",
     assignedUsersStream.Length, resultStream.ToArray().Length);

另外，您不需要在写行中包含所有这些ToString()。

PS:BinaryFormatter对字符串所做的所有操作均使用长度前缀写入字节。如果不需要前缀(我的猜测)，它可能变为:

string users = "";//Really long string goes here
byte[] result;

using (MemoryStream resultStream = new MemoryStream())
{
    using (DeflateStream compressionStream = new DeflateStream(resultStream,
             CompressionLevel.Optimal))
    {
        byte[] inBuffer = Encoding.UTF8.GetBytes(users);
        compressionStream.Write(inBuffer, 0, inBuffer.Length);
    }
    result = resultStream.ToArray();
}

反向操作同样简单，但是您需要估计最大长度才能创建读取缓冲区:

string users2 = null;

using (MemoryStream resultStream = new MemoryStream(result))
{
    using (DeflateStream compressionStream = new  DeflateStream(resultStream,
            CompressionMode.Decompress))
    {
        byte[] outBuffer = new byte[2048];   // need an estimate here
        int length = compressionStream.Read(outBuffer, 0, outBuffer.Length);
        users2 = Encoding.UTF8.GetString(outBuffer, 0, length);
    }
}

关于c# - DeflateStream在MemoryStream上不起作用吗？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/18540125/