文件切割与合并

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace Client
{
    /// <summary>
    /// 文件切割与合并
    /// </summary>
    public class FilePartitions
    {
        #region const params
        private const Int32 DefaultMaxEdges = 5 * 1024; //默认切割边界 5M
        private String TargetFilePrefix = "part_"; //生成文件的前缀
        #endregion

        #region private params
        private Int32 iMaxEdges = 0;
        private String strTargetDir = String.Empty;
        private Int32 iFileCount = 0;
        #endregion

        #region Attribute
        /// <summary>
        /// 文件切割边界
        /// </summary>
        public Int32 MaxEdges { get { return iMaxEdges > 0 ? iMaxEdges : DefaultMaxEdges; } set { iMaxEdges = value; } }

        /// <summary>
        /// 切割文件放置位置
        /// 未设置将与源文件放置同一目录
        /// </summary>
        public String TargetDir
        {
            get { return String.Empty.Equals(strTargetDir) ? Path.GetDirectoryName(SourceFile) : strTargetDir; }
            set { strTargetDir = value; }
        }

        /// <summary>
        /// 源文件
        /// </summary>
        public String SourceFile { get; set; }

        /// <summary>
        /// 总生成的文件数
        /// </summary>
        public Int32 FileCount { get { return iFileCount; } }

        /// <summary>
        /// 切割后文件前缀
        /// </summary>
        public String FilePrefix { get { return TargetFilePrefix; } set { TargetFilePrefix = value; } }

        #endregion

        public FilePartitions()
        {

        }

        public FilePartitions(String sourceFileName)
        {
            SourceFile = sourceFileName;
            if (!File.Exists(SourceFile))
                throw new Exception(String.Format("待处理文件 {0} 不存在!", SourceFile));
        }
        /// <summary>
        /// 切割文件为小块文件流
        /// </summary>
        /// <param name="filename"></param>
        /// <returns></returns>
        public IEnumerator<byte[]> GetFileBytes(string filename)
        {
            FileStream sourceStream = null;
            BinaryReader SplitFileReader = null;
            int iFileSize = MaxEdges * 1024;
            byte[] TempBytes;
            using (sourceStream = new FileStream(SourceFile, FileMode.Open, FileAccess.Read))
            {
                using (SplitFileReader = new BinaryReader(sourceStream))
                {
                    if (sourceStream.Length % iFileSize == 0)
                    {
                        iFileCount = (int)(sourceStream.Length / iFileSize);
                    }
                    else
                    {
                        iFileCount = (int)(sourceStream.Length / iFileSize) + 1;
                    }
                    for (var i = 1; i <= iFileCount; i++)
                    {
                        TempBytes = SplitFileReader.ReadBytes(iFileSize);
                        yield return TempBytes;
                    }
                }
            }
        }
        /// <summary>
        /// 切割文件为小块文件流
        /// </summary>
        /// <returns></returns>
        public IEnumerator<byte[]> GetFileBytes()
        {
            return GetFileBytes(SourceFile);
        }
        /// <summary>
        /// 合并文件【文件还原】
        /// </summary>
        /// <returns></returns>
        public Boolean OnMergeFiles()
        {
            Boolean bResult = true;
            FileStream AddStream = null;
            BinaryWriter AddWriter = null;
            FileStream TempStream = null;
            BinaryReader TempReader = null;
            try
            {

                string[] arrFileNames = Directory.GetFiles(TargetDir);
                List<FileInfoExt> fileInfo = new List<FileInfoExt>();
                foreach (String fileName in arrFileNames)
                {
                    String f1 = Path.GetFileName(fileName);
                    if (f1.IndexOf(FilePrefix) == 0)
                        fileInfo.Add(new FileInfoExt() { FileFullname = fileName, Filename = f1, FileCrTime = File.GetLastWriteTime(fileName) });
                }
                fileInfo = fileInfo.OrderBy(p => p.FileCrTime).ToList();
                iFileCount = fileInfo.Count;

                AddStream = new FileStream(SourceFile, FileMode.OpenOrCreate);
                AddWriter = new BinaryWriter(AddStream);

                foreach (FileInfoExt fileName in fileInfo)
                {
                    TempStream = new FileStream(fileName.FileFullname, FileMode.Open, FileAccess.Read);
                    TempReader = new BinaryReader(TempStream);
                    AddWriter.Write(TempReader.ReadBytes((int)TempStream.Length));
                    TempReader.Close();
                    TempReader.Close();
                }

            }
            catch (Exception ex)
            {
                bResult = false;
                throw ex;
            }
            finally
            {
                if (TempReader != null) TempReader.Close();
                if (TempStream != null) TempStream.Close();
                if (AddStream != null) AddStream.Close();
                if (AddWriter != null) AddWriter.Close();
            }
            return bResult;
        }
    }

    public class FileInfoExt
    {
        /// <summary>
        /// 文件完整路径
        /// </summary>
        public String FileFullname { get; set; }
        /// <summary>
        /// 文件名
        /// </summary>
        public String Filename { get; set; }
        /// <summary>
        /// 最后修改时间
        /// </summary>
        public DateTime FileCrTime { get; set; }

    }

}