c# 从服务器下载资源

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最新推荐文章于 2025-06-22 02:25:20 发布

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分类专栏： unity c#

本文链接：https://blog.youkuaiyun.com/qq_36565626/article/details/78584853

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本文介绍了使用C#进行文件下载的四种方法：TransmitFile、WriteFile及其分块下载方式和流方式。每种方法均提供了详细的代码示例，帮助读者理解和实践。

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try
{
string savePath = ""//保存路劲
downFileUrl = "";//下载文件链接地址
WebClient wcClient = new WebClient();
WebRequest webReq = WebRequest.Create(downFileUrl);
WebResponse webRes = webReq.GetResponse();
int fileLength = webRes.ContentLength;
Stream srm = webRes.GetResponseStream();
StreamReader srmReader = new StreamReader(srm);
byte[] bufferbyte = new byte[fileLength];
int allByte = (int)bufferbyte.Length;
int startByte = 0;
while (fileLength > 0)
{
//Application.DoEvents();
int downByte = srm.Read(bufferbyte, startByte, allByte);
if (downByte == 0) { break; };
startByte += downByte;
allByte -= downByte;
}
if (!File.Exists(savePath))
{
string[] dirArray = savePath.Split('\\');
string temp = string.Empty;
for (int i = 0; i < dirArray.Length - 1; i++)
{
temp += dirArray[i].Trim() + "\\";
if (!Directory.Exists(temp))
Directory.CreateDirectory(temp);
}
}
FileStream fs = new FileStream(savePath, FileMode.OpenOrCreate, FileAccess.Write);
fs.Write(bufferbyte, 0, bufferbyte.Length);
srm.Close();
srmReader.Close();
fs.Close();
}
catch (WebException ex)
{
throw ex;

}

C#从服务器下载文件可以使用下面4个方法：TransmitFile、WriteFile、WriteFile和流方式下载文件，并保存为相应类型，方法如下：

1、TransmitFile实现下载

protected void Button1_Click(object sender, EventArgs e)

    {

        /* 

        微软为<a
 href="https://www.baidu.com/s?wd=Response%E5%AF%B9%E8%B1%A1&tn=44039180_cpr&fenlei=mv6quAkxTZn0IZRqIHckPjm4nH00T1YvrjcvnHc3njI9uWD3uAnY0ZwV5Hcvrjm3rH6sPfKWUMw85HfYnjn4nH6sgvPsT6KdThsqpZwYTjCEQLGCpyw9Uz4Bmy-bIi4WUvYETgN-TLwGUv3EnHfLPW6vn1nk" target="_blank"
 class="baidu-highlight">Response对象</a>提供了一个新的方法TransmitFile来解决使用Response.BinaryWrite 

        下载超过400mb的文件时导致Aspnet_wp.exe进程回收而无法成功下载的问题。 

        代码如下： 

        */ 

        Response.ContentType = "application/x-zip-compressed";

        Response.AddHeader("Content-Disposition", "attachment;filename=z.zip");

        string filename = Server.MapPath("DownLoad/z.zip");

        Response.TransmitFile(filename);

    }

2、WriteFile实现下载

protected void Button2_Click(object sender, EventArgs e)

    {

        /* 

        using System.IO;

        */

        string fileName = "asd.txt";//客户端保存的文件名 

        string filePath = Server.MapPath("DownLoad/aaa.txt");//路径

        FileInfo fileInfo = new FileInfo(filePath);

        Response.Clear();

        Response.ClearContent();

        Response.ClearHeaders();

        Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);

        Response.AddHeader("Content-Length", fileInfo.Length.ToString());

        Response.AddHeader("Content-Transfer-Encoding", "binary");

        Response.ContentType = "application/octet-stream";

        Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312");

        Response.WriteFile(fileInfo.FullName);

        Response.Flush();

        Response.End();

    }

3、WriteFile分块下载

protected void Button3_Click(object sender, EventArgs e)

    {

        string fileName = "aaa.txt";//客户端保存的文件名 

        string filePath = Server.MapPath("DownLoad/aaa.txt");//路径

        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];

            Response.Clear();

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

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

            Response.ContentType = "application/octet-stream";

            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();

        }

    }

4、流方式下载

protected void Button4_Click(object sender, EventArgs e)

    {

        string fileName = "aaa.txt";//客户端保存的文件名 

        string filePath = Server.MapPath("DownLoad/aaa.txt");//路径

        //以字符流的形式下载文件 

        FileStream fs = new FileStream(filePath, FileMode.Open);

        byte[] bytes = new byte[(int)fs.Length];

        fs.Read(bytes, 0, bytes.Length);

        fs.Close();

        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.BinaryWrite(bytes);

        Response.Flush();

        Response.End();

    }