using System;
using System.Collections.Generic;
using System.Data.OleDb;
using System.IO;
//using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace FileManagerApp
{
    public partial class DownLoadFiles : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            try
            {
                //DownFile(HttpUtility.UrlDecode(Request.QueryString["FilePath"].ToString(), System.Text.Encoding.UTF8), HttpUtility.UrlDecode(Request.QueryString["FileName"].ToString(), System.Text.Encoding.UTF8));
                DownLoadFile(HttpUtility.UrlDecode(Request.QueryString["FilePath"].ToString(), System.Text.Encoding.UTF8));
            }
            catch (Exception ex)
            {
                Response.Write(ex.Message);
                Response.Flush();
                Response.End();
            }
        }


        private void DownFile(string FilePath, string FileName)
        {
            //WriteLog(FilePath);
            string fileName = FileName;//客户端保存的文件名
            string filePath = Server.MapPath("Files/" + FilePath);//路径

            //以字符流的形式下载文件
            //FileStream fs = null;
            //byte[] bytes=null;
            try
            {
                FileInfo fi = new FileInfo(FilePath);
                Response.Clear();
                Response.ClearHeaders();
                Response.Buffer = false;
                //fs = new FileStream(filePath, FileMode.Open);
                //bytes = new byte[(int)fs.Length];
                //fs.Read(bytes, 0, bytes.Length);
                Response.ContentType = "application/octet-stream";
                //通知浏览器下载文件而不是打开
                Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));
                //Response.AppendHeader("Content-Length", fi.Length.ToString());
                Response.WriteFile(filePath);
                Response.Flush();
                Response.End();
            }
            catch (Exception ex)
            {
                Response.Write(ex.Message);
                Response.End();
            }
            finally
            {
                //fs.Close();
            }


        }




        /// <summary>
        /// 使用OutputStream.Write分块下载文件，参数为文件绝对路径
        /// </summary>
        /// <param name="FileName"></param>
        public void DownLoadFile(string filePath)
        {
            string filePaths = Server.MapPath("Files/" + filePath);
            string file_name = HttpUtility.UrlEncode(Path.GetFileName(filePaths));
            //指定块大小
            long chunkSize = 204800;
            //建立一个200K的缓冲区
            byte[] buffer = new byte[chunkSize];
            //已读的字节数
            long dataToRead = 0;
            FileStream stream = null;
            try
            {
                //打开文件
                stream = new FileStream(filePaths, 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=" + file_name);
                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();
                        buffer = new Byte[chunkSize];
                        dataToRead = dataToRead - length;
                    }
                    else
                    {
                        //防止client失去连接
                        dataToRead = -1;
                    }
                }
                WriteLog(filePath, file_name);
            }
            catch (Exception ex)
            {
                throw ex;
                //HttpContext.Current.Response.Write("Error:" + ex.Message);
            }
            finally
            {
                if (stream != null)
                {
                    stream.Close();
                }
                HttpContext.Current.Response.Close();
            }
        }

        /// <summary>
        /// 写入下载日志
        /// </summary>
        /// <param name="file_name"></param>
        /// <param name="file_id"></param>
        private void WriteLog(string file_path,string file_name)
        {
            string user_id = string.Empty;
            try
            {
                user_id = HttpUtility.UrlDecode(Request.Cookies["USERID"].Value).Split('|')[0];
            }
            catch { }
            finally
            {
                OleDbConnection conn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Server.MapPath("./") + "db.mdb"); //Jet OLEDB:Database Password=

                try
                {
                    OleDbCommand cmd = conn.CreateCommand();
                    cmd.CommandText = "insert into EI_FILE_DOWNLOAD_LOG_T values( '" + Guid.NewGuid().ToString() + "','" + file_name + "','" + PublicVarClass.UserID + "','" + GetIPAddress() + "',now(),'"+file_path+"')";
                    cmd.Connection = conn;
                    conn.Open();
                    cmd.ExecuteNonQuery();
                }
                catch (Exception ex) { }
                finally
                {
                    conn.Close();
                    conn.Dispose();
                }
            }
        }


        #region 获取IP地址
        /// <summary>
        /// 获取IP地址
        /// </summary>
        /// <returns></returns>
        public string GetIPAddress()
        {
            string userIP = string.Empty;
            HttpRequest request = HttpContext.Current.Request;
            //如果使用代理，获取真实IP

            if (request.ServerVariables["HTTP_X_FORWARDED_FOR"] != "")
            {
                userIP = request.ServerVariables["REMOTE_ADDR"];
            }
            else
            {
                userIP = request.ServerVariables["HTTP_X_FORWARDED_FOR"];
            }
            if (userIP == null || userIP == "")
            {
                userIP = request.UserHostAddress;
            }
            return userIP;

        }
        #endregion
    }
}