c#文件下载示例的4种方法

原文链接：http://www.jb51.net/article/57068.htm

C#实现HTTP下载文件的方法

/// <summary>
/// Http下载文件
/// </summary>
public static string HttpDownloadFile(string url, string path)
{
    // 设置参数
    HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
    //发送请求并获取相应回应数据
    HttpWebResponse response = request.GetResponse() as HttpWebResponse;
    //直到request.GetResponse()程序才开始向目标网页发送Post请求
    Stream responseStream = response.GetResponseStream();
    //创建本地文件写入流
    Stream stream = new FileStream(path, FileMode.Create);
    byte[] bArr = new byte[1024];
    int size = responseStream.Read(bArr, 0, (int)bArr.Length);
    while (size > 0)
    {
        stream.Write(bArr, 0, size);
        size = responseStream.Read(bArr, 0, (int)bArr.Length);
    }
    stream.Close();
    responseStream.Close();
    return path;
}

原文链接：http://www.jb51.net/article/47822.htm

1、TransmitFile实现下载

protected void Button1_Click(object sender, EventArgs e)
{
    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

//WriteFile实现下载
protected void Button2_Click(object sender, EventArgs e)
{
    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

//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

//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();
}