导出下载csv以及编码问题

文件的读写,总会遇到编码问题.如果在写文件的时候就确定编码,那么在读取下载的时候就会很方便

 private bool WriteInExportedFile(string strPath, DataColumnCollection tableColumns, DataRowCollection tableRows)
        {
            bool flag = true;

            //这里必须设置写入文件的编码,在读取的时候才不需要设置!!!!
            System.IO.StreamWriter File = new System.IO.StreamWriter(strPath, false, System.Text.Encoding.GetEncoding("gb2312"));

            int rowscreated = 0;

            string sqlinsert = "";
            try
            {
                //Loop through columns of table to generate first row of CSV file
                int ctrColumn = 0;
                foreach (DataColumn dc in tableColumns)
                {
                    if (ctrColumn < tableColumns.Count - 1)
                        sqlinsert += dc.ColumnName.ToString() + ",";
                    else
                        sqlinsert += dc.ColumnName.ToString();

                    ctrColumn++;
                }
                File.WriteLine(sqlinsert);

                foreach (DataRow row in tableRows)
                {
                    sqlinsert = "";
                    string sqlvalues = "";
                    object[] rowItems = row.ItemArray;

                    ctrColumn = 0;
                    foreach (DataColumn dcol in tableColumns)
                    {
                        if (ctrColumn < tableColumns.Count - 1)
                            sqlvalues += rowItems[ctrColumn].ToString().Replace("''", "'") + ",";
                        else
                            sqlvalues += rowItems[ctrColumn].ToString().Replace("''", "'");

                        ctrColumn++;
                    }

                    sqlinsert = sqlinsert + sqlvalues;

                    File.WriteLine(sqlinsert);

                    rowscreated++;
                }
                File.Close();
            }
            catch (Exception ae) //Error
            {
                flag = false;
            }
            finally
            {
                File.Close();
            }
            return flag;
        }

  public void MyDirectDownFile(string filepath)
        {
            //客户端保存的文件名
            filename = "我的csv.csv";
            FileInfo fileInfo = new FileInfo(filepath);

            //清除不必要的头,基类中可能乱添加的东西!
            Response.Clear();
            Response.ClearContent();
            Response.ClearHeaders();

            // HttpUtility.UrlEncode(filename) 是使得文件名正确显示
            Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(filename));
            Response.AddHeader("Content-Length", fileInfo.Length.ToString());

            // Response.ContentType 的种类有很多!
            Response.ContentType = "application/octet-stream";
            Response.WriteFile(fileInfo.FullName);

            //这样就可以抛出下载了!
            Response.Flush();
            Response.End();
        }

  public void MyFlushDownFile(string filename, string filepath)
        {
            filename = "我的csv.csv";//客户端保存的文件名

            //读取文件,希望这个文件在写入的时候是gb2312写入的,那么导出就不会有乱码了!
            System.IO.FileInfo fileInfo = new System.IO.FileInfo(filepath);

            if (fileInfo.Exists == true)
            {
                const long ChunkSize = 102400;//100K 每次读取文件，只读取100K，这样可以缓解服务器的压力

                byte[] buffer = new byte[ChunkSize];

                System.IO.FileStream iStream = System.IO.File.OpenRead(filepath);

                long dataLengthToRead = iStream.Length;//获取下载的文件总大小


                //这几句话是必须要的,如果没有,基类中可能有方法向里面乱添加东西!!!
                Response.Clear();
                Response.ClearContent();
                Response.ClearHeaders();
                //同样,这里没有设置编码,因为读取的文件中设置了gb2312,这里就没有必要了!

                // Response.ContentType 的种类有很多!
                Response.ContentType = "application/octet-stream";

                // HttpUtility.UrlEncode(filename) 是使得文件名正确显示
                Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName));

                while (dataLengthToRead > 0 && Response.IsClientConnected)
                {
                    int lengthRead = iStream.Read(buffer, 0, Convert.ToInt32(ChunkSize));//读取的大小

                    Response.OutputStream.Write(buffer, 0, lengthRead);

                    Response.Flush();

                    dataLengthToRead = dataLengthToRead - lengthRead;
                }

                Response.Close();
            }
        }

请看具体使用:

 //先写入
bool flag = WriteInExportedFile(filePath, dt.Columns, dt.Rows);

//再导出
 if (flag)
 {
        DownFile(fileName, filePath);
 }