求获取文件流并输出到客户端的方法

Question

            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);
            request.Timeout = 150000;            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            WebHeaderCollection whc = response.Headers;
            Stream stream = response.GetResponseStream();            Response.Clear();
            Response.ContentType = "application/pdf";
            
            long len = stream.Length; //这里报错:此流不支持查找操作
            byte[] bytes = new byte[len];
            stream.Read(bytes, 0, (int)len);
            Response.BinaryWrite(bytes);
这是我自己写的程序，目的是实现从一个服务器获取一个文件流，然后输出到客户端，实现下载。看来我这个方法是不行了，所以请大家帮忙，不胜感激！100分献上。

Answer 1

Response.Clear();
Response.ClearHeaders();
Response.Buffer = false;
Response.AddHeader("content-disposition", "attachment;filename=" + Server.UrlEncode(文件名));
Response.AddHeader("Content-Length", 文件长度);
Response.ContentType = "application/octet-stream";
Response.ContentEncoding = System.Text.Encoding.Default;
Response.WriteFile(文件全路径);

Answer 2

 System.DateTime currentTime = new System.DateTime();
            currentTime = System.DateTime.Now;
            string fileName = currentTime.Year.ToString() + "_" + currentTime.Month.ToString() + currentTime.Day.ToString() + "_" + currentTime.Hour.ToString() + currentTime.Minute.ToString() + ".csv";
            #endregion            #region Create StringWriter            StringWriter sw = new StringWriter();
            int tableRowLength = m_dt.Rows.Count;
            // int tableColumnLength = dt.Columns.Count;
            for (int i = 0; i < tableRowLength; ++i)
            {
                sw.WriteLine(m_dt.Rows[i][0].ToString() + @"," + m_dt.Rows[i][1].ToString() + @"," + m_dt.Rows[i][2].ToString() + @"," + m_dt.Rows[i][3].ToString() + @"," + m_dt.Rows[i][4].ToString() + @"," + m_dt.Rows[i][5].ToString() + @"," + m_dt.Rows[i][6].ToString());
            }            #endregion            #region Download file            Response.Clear();
            Response.Buffer = true;
            Response.ContentEncoding = System.Text.Encoding.Default;
            Response.ContentType = "text/csv";
            Response.AppendHeader("content-disposition", "attachment; filename=" + fileName);
            Response.Write(sw.ToString());
            Response.Flush();
            Response.End();

Answer 3

void Download()
{
System.IO.FileStream r = new System.IO.FileStream(FileName, System.IO.FileMode.Open);  
//设置基本信息  
Response.Buffer= false;  
Response.AddHeader("Connection", "Keep-Alive");  
Response.ContentType = "application/octet-stream";  
Response.AddHeader("Content-Disposition", "attachment;filename=" + System.IO.Path.GetFileName(FileName));  
Response.AddHeader("Content-Length", r.Length.ToString());  
while (true)  
{  
//开辟缓冲区空间  
byte[] buffer = new byte[1024];  
//读取文件的数据  
int leng = r.Read(buffer, 0, 1024);  
(leng == 0)//到文件尾，结束  
break;  
if (leng == 1024)//读出的文件数据长度等于缓冲区长度，直接将缓冲区数据写入  
Response.BinaryWrite(buffer);  
else  
{  
//读出文件数据比缓冲区小，重新定义缓冲区大小，只用于读取文件的最后一个数据块  
byte[] b = new byte[leng];  
for (int i = 0; i < leng; i++)  
b[i] = buffer[i];  
Response.BinaryWrite(b);  
}  
}  
r.Close();//关闭下载文件  
Response.End();//结束文件下载  
} 

Answer 4

string fileName = currentTime.Year.ToString() + "_" + currentTime.Month.ToString() + currentTime.Day.ToString() + "_" + currentTime.Hour.ToString() + currentTime.Minute.ToString() + ".csv";对于这种写法我很无奈

Answer 5

GetResponseStream 得到的流是无法查找的你可以先把这个流复制到MemoryStream里
private void CopyStream(Stream source, Stream dest)
    {       const int BUFFER_LENGTH = 1024; 
        int bytesRead = 0;   
        do
        {
            byte[] buffer = new byte[BUFFER_LENGTH];
            bytesRead = source.Read(buffer, 0, buffer.Length);
            dest.Write(buffer, 0, bytesRead);
        }
        while (bytesRead > 0);
    }
这样，就可以读取MemoryStream的长度了            
            Stream stream = response.GetResponseStream();
            using (MemoryStream ms = new MemoryStream())
            {
                CopyStream(stream, ms);
                long len = ms.Length; 
            }

Answer 6

System.IO.Stream iStream = null;// 读去缓冲区的大小
byte[] buffer = new Byte[10000];// 文件程度
int length;// 读去的总字节数:
long dataToRead;// 下载的文件路径标式符.
string filepath  = "DownloadFileName";// 文件名称
string  filename  = System.IO.Path.GetFileName(filepath);try
{
// 打开文件
iStream = new System.IO.FileStream(filepath, System.IO.FileMode.Open, 
System.IO.FileAccess.Read,System.IO.FileShare.Read);
// 获得文件总大小
dataToRead = iStream.Length;Response.ContentType = "application/octet-stream";
Response.AddHeader("Content-Disposition", "attachment; filename=" + filename);// 开始读取
  while (dataToRead > 0)
{
 
if (Response.IsClientConnected) 
{
// 从缓冲区中读取.
length = iStream.Read(buffer, 0, 10000);// 将数据写入当前文件流中
Response.OutputStream.Write(buffer, 0, length);// 刷新数据并输出到html
Response.Flush();buffer= new Byte[10000];
dataToRead = dataToRead - length;
}
else
{
//如果客户端中断操作则停止读取
dataToRead = -1;
}
}
}
catch (Exception ex) 
{
// 如果发生错误,输出错误信息
Response.Write("Error : " + ex.Message);
}
finally
{
if (iStream != null) 
{
//Close the file.
iStream.Close();
}
}

Answer 7

            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(gxUrl);
            request.Timeout = 1500000;            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            Stream stream = response.GetResponseStream();            Response.Clear();
            Response.ContentType = "application/pdf";            int buffer = 1024;
            int alreadyRead = 0;
            do
            {
                byte[] bytes = new byte[buffer];
                alreadyRead = stream.Read(bytes, 0, buffer);
                Response.BinaryWrite(bytes);
                Response.Flush();
            } while (alreadyRead > 0);用7楼哥们提供的方法，改成这样，运行不出错。但出来的PDF图像，只有最上边的一部分，郁闷。

Answer 8

自己搞定了            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(gxUrl);
            request.Timeout = 1500000;            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            Stream stream = response.GetResponseStream();            Response.Clear();
            Response.ContentType = "application/pdf";
            Response.AddHeader("Content-Disposition", "attachment;filename=CNKI.PDF");
            
            int buffer = 1024;
            while (true)
            {
                byte[] bytes = new byte[buffer];
                int alreadyRead = stream.Read(bytes, 0, buffer);
                if (alreadyRead == 0) break;
                if (alreadyRead == buffer)
                    Response.BinaryWrite(bytes);
                else
                {
                    byte[] lastBytes = new byte[alreadyRead];
                    for (int i = 0; i < alreadyRead; i++)
                        lastBytes[i] = bytes[i];
                    Response.BinaryWrite(lastBytes);
                }
            }
            Response.End();多谢大家帮忙，稍候结贴！