Question

我无法在点击按钮上下载图像..我已将按钮放在网格内以下载相应的图像..下面是我的代码。

protected void DownloadFile(object sender, EventArgs e)
{
    int id = int.Parse((sender as LinkButton).CommandArgument);
    byte[] bytes;
    string fileName, contentType;
    string constr = ConfigurationManager.ConnectionStrings["sqlcon"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand())
        {
            cmd.CommandText = "select FileName,Extentions, FileContent from Documents where ID=" + id;
            cmd.Parameters.AddWithValue("@Id", id);
            cmd.Connection = con;
            con.Open();
            using (SqlDataReader sdr = cmd.ExecuteReader())
            {
                sdr.Read();
                bytes = (byte[])sdr["FileContent"];
                contentType = sdr["Extentions"].ToString();
                fileName = sdr["FileName"].ToString();
            }
            con.Close();
        }
    }
    Response.Clear();
    Response.Buffer = true;
    Response.Charset = "";
    Response.Cache.SetCacheability(HttpCacheability.NoCache);
    Response.ContentType = contentType;
    Response.AddHeader("Content-type", contentType);
    Response.AddHeader("Content-Disposition", "attachment; filename=" + fileName);
    Response.BinaryWrite(bytes);
    Response.Flush();
    Response.End();
}

Answer 1

将CommandText更改为此：

cmd.CommandText = "select FileName,Extentions, FileContent from Documents where ID=@Id";

读者读到这个：

 while(sdr.Read())
 {
                bytes = (byte[])sdr["FileContent"];
                contentType = sdr["Extentions"].ToString();
                fileName = sdr["FileName"].ToString();
 }

编辑：为了测试，我使用以下代码从我的磁盘而不是DataBase获取文件：

protected void DownloadFile(object sender, EventArgs e)
{
    int id = int.Parse((sender as LinkButton).CommandArgument);
    byte[] bytes;
    string fileName, contentType;

    // Test code  to download 123.sql file from C:\
    bytes = System.IO.File.ReadAllBytes("C:\\123.sql");
    contentType = ".sql";
    fileName = "123.sql";
    //string constr = ConfigurationManager.ConnectionStrings["sqlcon"].ConnectionString;
    //using (SqlConnection con = new SqlConnection(constr))
    //{
    //    using (SqlCommand cmd = new SqlCommand())
    //    {
    //        cmd.CommandText = "select FileName,Extentions, FileContent from Documents where ID=" + id;
    //        cmd.Parameters.AddWithValue("@Id", id);
    //        cmd.Connection = con;
    //        con.Open();
    //        using (SqlDataReader sdr = cmd.ExecuteReader())
    //        {
    //            sdr.Read();
    //            bytes = (byte[])sdr["FileContent"];
    //            contentType = sdr["Extentions"].ToString();
    //            fileName = sdr["FileName"].ToString();
    //        }
    //        con.Close();
    //    }
    //}
    Response.Clear();
    Response.Buffer = true;
    Response.Charset = "";
    Response.Cache.SetCacheability(HttpCacheability.NoCache);
    Response.ContentType = contentType;
    Response.AddHeader("Content-type", contentType);
    Response.AddHeader("Content-Disposition", "attachment; filename=" + fileName);
    Response.BinaryWrite(bytes);
    Response.Flush();
    Response.End();
}

编辑2： Here是我使用的测试项目的链接。

图像不是通过按钮点击下载，即放置在网格内

1 个答案: