C#文件通用下载类

//=====================================================================================
// All Rights Reserved , Copyright
//=====================================================================================
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Web;
using System.Threading;

namespace Utilities
{
    /// <summary>
    /// 文件下载类
    /// </summary>
    public class FileDownHelper
    {
        public FileDownHelper()
        { }
        /// <summary>
        /// 参数为虚拟路径
        /// </summary>
        public static string FileNameExtension( string FileName)
        {
            return Path .GetExtension(MapPathFile(FileName));
        }

        /// <summary>
        /// 获取物理地址
        /// </summary>
        public static string MapPathFile( string FileName)
        {
            return HttpContext .Current.Server.MapPath(FileName);
        }
        /// <summary>
        /// 验证文件是否存在
        /// </summary>
        /// <param name=" FileName"></param>
        /// <returns></returns>
        public static bool FileExists( string FileName)
        {
            string destFileName = MapPathFile(FileName);
            if (File .Exists(destFileName))
            {
                return true ;
            }
            else
            {
                return false ;
            }
        }
        /// <summary>
        /// 普通下载
        /// </summary>
        /// <param name=" FileName">文件虚拟路径 </param>
        ///  /// <param name=" name">返回客户端名称 </param>
        public static void DownLoadold( string FileName, string name)
        {
            string destFileName = MapPathFile(FileName);
            if (File .Exists(destFileName))
            {
                FileInfo fi = new FileInfo(destFileName);
                HttpContext.Current.Response.Clear();
                HttpContext.Current.Response.ClearHeaders();
                HttpContext.Current.Response.Buffer = false ;
                HttpContext.Current.Response.AppendHeader("Content-Disposition" , "attachment;filename=" + HttpUtility.UrlEncode(name, System.Text.Encoding .UTF8));
                HttpContext.Current.Response.AppendHeader("Content-Length" , fi.Length.ToString());
                HttpContext.Current.Response.ContentType = "application/octet-stream" ;
                HttpContext.Current.Response.WriteFile(destFileName);
                HttpContext.Current.Response.Flush();
                HttpContext.Current.Response.End();
            }
        }

        /// <summary>
        /// 分块下载
        /// </summary>
        /// <param name=" FileName">文件虚拟路径 </param>
        public static void DownLoad( string FileName)
        {
            string filePath = MapPathFile(FileName);
            long chunkSize = 204800;             //指定块大小
            byte[] buffer = new byte[chunkSize]; //建立一个200K的缓冲区
            long dataToRead = 0;                 //已读的字节数  
            FileStream stream = null ;
            try
            {
                //打开文件  
                stream = new FileStream (filePath, FileMode.Open, FileAccess.Read, FileShare .Read);
                dataToRead = stream.Length;

                //添加Http头  
                HttpContext.Current.Response.ContentType = "application/octet-stream" ;
                HttpContext.Current.Response.AddHeader("Content-Disposition" , "attachement;filename=" + HttpUtility.UrlEncode(Path .GetFileName(filePath)));
                HttpContext.Current.Response.AddHeader("Content-Length" , dataToRead.ToString());

                while (dataToRead > 0)
                {
                    if (HttpContext .Current.Response.IsClientConnected)
                    {
                        int length = stream.Read(buffer, 0, Convert .ToInt32(chunkSize));
                        HttpContext.Current.Response.OutputStream.Write(buffer, 0, length);
                        HttpContext.Current.Response.Flush();
                        HttpContext.Current.Response.Clear();
                        dataToRead -= length;
                    }
                    else
                    {
                        dataToRead = -1; //防止client失去连接
                    }
                }
            }
            catch (Exception ex)
            {
                HttpContext.Current.Response.Write("Error:" + ex.Message);
            }
            finally
            {
                if (stream != null ) stream.Close();
                HttpContext.Current.Response.Close();
            }
        }

        /// <summary>
        ///  输出硬盘文件，提供下载 支持大文件、续传、速度限制、资源占用小
        /// </summary>
        /// <param name=" _Request">Page.Request对象 </param>
        /// <param name=" _Response">Page.Response对象 </param>
        /// <param name=" _fileName">下载文件名 </param>
        /// <param name=" _fullPath">带文件名下载路径 </param>
        /// <param name=" _speed">每秒允许下载的字节数 </param>
        /// <returns> 返回是否成功 </returns>
        //---------------------------------------------------------------------
        //调用：
        // string FullPath=Server.MapPath("count.txt");
        // ResponseFile(this.Request,this.Response,"count.txt",FullPath,100);
        //---------------------------------------------------------------------
        public static bool ResponseFile( HttpRequest _Request, HttpResponse _Response, string _fileName, string _fullPath, long _speed)
        {
            try
            {
                FileStream myFile = new FileStream(_fullPath, FileMode.Open, FileAccess .Read, FileShare.ReadWrite);
                BinaryReader br = new BinaryReader(myFile);
                try
                {
                    _Response.AddHeader( "Accept-Ranges", "bytes" );
                    _Response.Buffer = false;

                    long fileLength = myFile.Length;
                    long startBytes = 0;
                    int pack = 10240;  //10K bytes
                    int sleep = (int )Math.Floor(( double)(1000 * pack / _speed)) + 1;

                    if (_Request.Headers["Range" ] != null)
                    {
                        _Response.StatusCode = 206;
                        string[] range = _Request.Headers["Range" ].Split(new char[] { '=', '-' });
                        startBytes = Convert.ToInt64(range[1]);
                    }
                    _Response.AddHeader( "Content-Length", (fileLength - startBytes).ToString());
                    if (startBytes != 0)
                    {
                        _Response.AddHeader( "Content-Range", string .Format(" bytes {0}-{1}/{2}", startBytes, fileLength - 1, fileLength));
                    }

                    _Response.AddHeader( "Connection", "Keep-Alive" );
                    _Response.ContentType = "application/octet-stream" ;
                    _Response.AddHeader( "Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(_fileName, System.Text.Encoding.UTF8));

                    br.BaseStream.Seek(startBytes, SeekOrigin.Begin);
                    int maxCount = (int )Math.Floor(( double)((fileLength - startBytes) / pack)) + 1;

                    for (int i = 0; i < maxCount; i++)
                    {
                        if (_Response.IsClientConnected)
                        {
                            _Response.BinaryWrite(br.ReadBytes(pack));
                            Thread.Sleep(sleep);
                        }
                        else
                        {
                            i = maxCount;
                        }
                    }
                }
                catch
                {
                    return false ;
                }
                finally
                {
                    br.Close();
                    myFile.Close();
                }
            }
            catch
            {
                return false ;
            }
            return true ;
        }




        /// <summary>
        /// 下载word
        /// </summary>
        /// <param name=" fileName">文件名称 </param>
        /// <param name=" html"></param>
        public static void HtmlToWord( string fileName,string html)
        {
       
            HttpContext.Current.Response.Clear();
            HttpContext.Current.Response.ClearHeaders();
            HttpContext.Current.Response.ContentType = "application/ms-word" ;
            HttpContext.Current.Response.AppendHeader("Content-Disposition" , "attachment;filename=" + HttpUtility.UrlDecode(fileName, System.Text.Encoding .UTF8) + ".doc");
            HttpContext.Current.Response.Write(html);         
            HttpContext.Current.Response.Flush();
            HttpContext.Current.Response.End();

        }
    }
}