C# System.IO.Seek方法代码示例

		/// <summary>Constructs a MetainfoFile</summary>
		/// <param name="istream">Stream to read data from</param>
		public MetainfoFile(IO.Stream istream)
		{
			BEncode.Dictionary mainDictionary = (BEncode.Dictionary)BEncode.NextElement(istream);
			this.announceUrl = mainDictionary.GetString(new BEncode.String("announce"));
			
			if (mainDictionary.Contains("comment"))
				this.comment = mainDictionary.GetString("comment");
			if (mainDictionary.Contains("created by"))
				this.createdBy = mainDictionary.GetString("created by");
			if (mainDictionary.Contains("creation date"))
			{
				int creation = mainDictionary.GetInteger("creation date");
				this.creationDate = new System.DateTime(1970, 1, 1, 0, 0, 0);
				this.creationDate = this.creationDate.AddSeconds(creation);
			}
			
			BEncode.Dictionary infoDictionary = mainDictionary.GetDictionary("info");
			this.name = infoDictionary.GetString("name");
			this.pieceLength = infoDictionary.GetInteger("piece length");

			this.pieceFileName = this.name.ToLower().Replace(' ', '_');
			
			// Get SHA digests
			byte[] pieces = infoDictionary.GetBytes("pieces");
			int numPieces = pieces.Length / 20;
			
			this.shaDigestList.Capacity = numPieces;
			
			for (int i=0; i<numPieces; ++i)
			{
				this.shaDigestList.Add( new ByteField20(pieces, i*20) );
			}
			
			// Get filenames and lengths
			if (infoDictionary.Contains("length"))
			{
				// one file
				this.fileList.Add(name);
				
				int fileLength = infoDictionary.GetInteger("length");
				this.fileLengthList.Add(fileLength);
				this.totalSize = fileLength;
			}
			else
			{
				// multiple files - a list of dictionaries containing the filename and length
				BEncode.List files = infoDictionary.GetList("files");
				this.fileList.Capacity = this.fileLengthList.Capacity = files.Count;
				this.totalSize = 0;
				
				foreach (BEncode.Dictionary fileDic in files)
				{
					BEncode.List pathList = fileDic.GetList("path");
					string path = this.name + IO.Path.DirectorySeparatorChar;
					
					for (int i=0; i<pathList.Count-1; ++i)
					{
						path += pathList[i].ToString() + IO.Path.DirectorySeparatorChar;
					}

					path += pathList[ pathList.Count-1 ];
					
					this.fileList.Add(path);
					
					int fileLength = fileDic.GetInteger("length");
					this.fileLengthList.Add(fileLength);
					this.totalSize += fileLength;
				}
			}
			
			// calculate the SHA-1 digest of the info dictionary - this is required for the tracker protocol
			istream.Seek(infoDictionary.Position, IO.SeekOrigin.Begin);
			byte[] infoData = new byte[ infoDictionary.Length ];
			istream.Read(infoData, 0, infoData.Length);
			
			this.infoDigest = ByteField20.ComputeSHAHash(infoData);
		}