如何在c＃下载服务器之前预览图像 [英] How to preview an image before downloading from server in c#

问题描述

当我们在查询字符串中有文件ID时，如何在C＃中从服务器下载之前预览图像。



我尝试过：



当我们在查询字符串中有文件id

解决方案时，如何在C＃中从服务器下载之前预览图像

我试过相同的pdf



但不能在jpg中做同样的事情



string id = Request [id]。ToString（）; //从网格点击查询字符串



string filename =;

string addr =;

string fpath =;

SqlConnection con = new SqlConnection（ConfigurationManager.AppSettings [OFcon]）;





con.Open（）;



string query =select addr，filename from file =+ id +; < br $>


SqlCommand cmd = new SqlCommand（query，con）;

SqlDataReader rd = cmd.ExecuteReader（）;



if（rd！= null）

{

if（rd.Read（））

{

addr = rd.GetString（0）;

filename = rd.GetString（1）;

fpath = addr + filename;



}

}



con.Close（）;

字符串路径= Server.MapPath（。）;

string path1 = path +\\+ fpath;

string viewpath = fpath;





string name = Path.GetFileName（fpath）;

string ext = Path.GetExtension（fpath）;

string FilePath = viewpath;

WebClient User = new WebClient（）;

Byte [] FileBuffer = User.DownloadData（FilePath）;

if（FileBuffer！= null）

{

Response.ContentType =application / pdf;

Response.AddHeader（ content-length，FileBuffer.Length.ToString（））;

Response.BinaryWrite（FileBuffer）;

}

}

How to preview an image before downloading from server in C# when we are having id of file in query string.

What I have tried:

how to preview an image before downloading from server in C# when we are having id of file in query string

解决方案

I have tried same for pdf

but not able to do same in jpg

string id = Request["id"].ToString(); // getting from grid click by query string

string filename = "";
string addr = "";
string fpath = "";
SqlConnection con = new SqlConnection(ConfigurationManager.AppSettings["OFcon"]);


con.Open();

string query = "select addr,filename from files where id=" + id + "";

SqlCommand cmd = new SqlCommand(query, con);
SqlDataReader rd = cmd.ExecuteReader();

if (rd != null)
{
if (rd.Read())
{
addr = rd.GetString(0);
filename = rd.GetString(1);
fpath = addr + filename;

}
}

con.Close();
string path = Server.MapPath(".");
string path1 = path + "\\" + fpath;
string viewpath = fpath;


string name = Path.GetFileName(fpath);
string ext = Path.GetExtension(fpath);
string FilePath = viewpath;
WebClient User = new WebClient();
Byte[] FileBuffer = User.DownloadData(FilePath);
if (FileBuffer != null)
{
Response.ContentType = "application/pdf";
Response.AddHeader("content-length", FileBuffer.Length.ToString());
Response.BinaryWrite(FileBuffer);
}
}

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