COM互操作IStream的包装类是否已存在?

确实如此, System.Runtime.InteropServices.ComTypes.IStream . 样品包装:

using System;
using iop = System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;

public class ComStreamWrapper : System.IO.Stream {
  private IStream mSource;
  private IntPtr mInt64;

  public ComStreamWrapper(IStream source) { 
    mSource = source;
    mInt64 = iop.Marshal.AllocCoTaskMem(8);
  }

  ~ComStreamWrapper() { 
    iop.Marshal.FreeCoTaskMem(mInt64); 
  }

  public override bool CanRead { get { return true; } }
  public override bool CanSeek { get { return true; } }
  public override bool CanWrite { get { return true; } }

  public override void Flush() { 
    mSource.Commit(0); 
  }

  public override long Length { 
    get { 
      STATSTG stat;
      mSource.Stat(out stat, 1);
      return stat.cbSize;
    }
  }

  public override long Position {
    get { throw new NotImplementedException(); }
    set { throw new NotImplementedException(); }
  }

  public override int Read(byte[] buffer, int offset, int count) {
    if (offset != 0) throw new NotImplementedException();
    mSource.Read(buffer, count, mInt64);
    return iop.Marshal.ReadInt32(mInt64);
  }

  public override long Seek(long offset, System.IO.SeekOrigin origin) {
    mSource.Seek(offset, (int)origin, mInt64);
    return iop.Marshal.ReadInt64(mInt64);
  }

  public override void SetLength(long value) {
    mSource.SetSize(value);
  }

  public override void Write(byte[] buffer, int offset, int count) {
    if (offset != 0) throw new NotImplementedException();
    mSource.Write(buffer, count, IntPtr.Zero);
  }
}