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长沙网站建设公司专业制作网站文件下载类

本文来源: asp.net文件下载      本文作者:长沙专业做网站      发布时间:2017-09-14


在开发资源下载站点的过程中,大多数程序员使用资源下载的方式就是使用普通的链接指向文件下载方式,这种方式很容易产生盗链现象,
长沙做网站公司为了提高下载效率以及下载数据的安全性整合了一个类文件。以下代码仅供参考:

using System.IO;
using System.Threading;
using System.Web;
/// <summary>
/// 文件下载类
/// </summary>
public class FileDown
{
    public FileDown()
    { }

    /// <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>
    /// 普通下载
    /// </summary>
    /// <param name="FileName">文件虚拟路径</param>
    public static void DownLoadold(string FileName)
    {
        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(Path.GetFileName(destFileName), 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;
    }
}


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