gzipfilter.cs

C#的zip的源代码

using System;
using System.IO;

using System.Text;
using System.Diagnostics;

using ICSharpCode.SharpZipLib.Zip.Compression;
using ICSharpCode.SharpZipLib.GZip;
using ICSharpCode.SharpZipLib.Zip.Compression.Streams;

namespace blowery.Web.HttpModules {
  /// <summary>
  /// This is a little filter to support HTTP compression using GZip
  /// </summary>
  public class GZipFilter : HttpCompressingFilter {

    /// <summary>
    /// compression stream member
    /// has to be a member as we can only have one instance of the
    /// actual filter class
    /// </summary>
    private GZipOutputStream m_stream = null;

    /// <summary>
    /// Primary constructor.  Need to pass in a stream to wrap up with gzip.
    /// </summary>
    /// <param name="baseStream">The stream to wrap in gzip.  Must have CanWrite.</param>
    public GZipFilter(Stream baseStream) : base(baseStream, CompressionLevels.Normal) { }

    /// <summary>
    /// Write content to the stream and have it compressed using gzip.
    /// </summary>
    /// <param name="buffer">The bytes to write</param>
    /// <param name="offset">The offset into the buffer to start reading bytes</param>
    /// <param name="count">The number of bytes to write</param>
    public override void Write(byte[] buffer, int offset, int count) {
      //      GZipOutputStream stream = new GZipOutputStream(BaseStream);
      //      stream.Write(buffer, offset, count);
      //      stream.Finish();
      if (m_stream == null)
        m_stream = new GZipOutputStream(BaseStream);
      m_stream.Write(buffer, offset, count);
    }

    /// <summary>
    /// The Http name of this encoding.  Here, gzip.
    /// </summary>
    public override string NameOfContentEncoding {
      get { return "gzip"; }
    }

    /// <summary>
    /// Closes this Filter and calls the base class implementation.
    /// </summary>
    public override void Close() {
      if (m_stream != null)
        m_stream.Finish();
      base.Close();
    }
  }
}