jQuery和ASP.NET从数据库下载文件
本文关键字：数据库 下载 文件 NET ASP jQuery | 更新日期: 2023-09-27 17:59:08
我查看了许多在线资源，并构建了我的脚本，但它似乎仍然没有给我文件。它只是加载页面"client-home2.aspx/downloadAttachment"，而不是执行代码和传递文件。
下面是我的代码：
[WebMethod]
public void downloadAttachment(string id)
{
DbProviderFactory dbf = DbProviderFactories.GetFactory();
using (IDbConnection con = dbf.CreateConnection())
{
string sSQL;
sSQL = "select top 1 " + ControlChars.CrLf
+ " FILENAME, FILE_MIME_TYPE, ATTACHMENT" + ControlChars.CrLf
+ " from vwATTACHMENTS_CONTENT" + ControlChars.CrLf
+ " where 1 = 1 " + ControlChars.CrLf;
//Debug.Print(sSQL);
using (IDbCommand cmd = con.CreateCommand())
{
cmd.CommandText = sSQL;
Sql.AppendParameter(cmd, id.ToString(), "ATTACHMENT_ID");
cmd.CommandText += " order by DATE_ENTERED desc" + ControlChars.CrLf;
using (DbDataAdapter da = dbf.CreateDataAdapter())
{
((IDbDataAdapter)da).SelectCommand = cmd;
using (DataTable dt = new DataTable())
{
da.Fill(dt);
if (dt.Rows.Count > 0)
{
foreach (DataRow r in dt.Rows)
{
string name = (string)r["FILENAME"];
string contentType = (string)r["FILE_MIME_TYPE"];
Byte[] data = (Byte[])r["ATTACHMENT"];
// Send the file to the browser
Response.AddHeader("Content-type", contentType);
Response.AddHeader("Content-Disposition", "attachment; filename=" + name);
Response.BinaryWrite(data);
Response.Flush();
Response.End();
}
}
else
{
}
}
}
}
}
}
这是我的jQuery:
$('.attachmentLink').click(function () {
var id = $(this).attr('id');
/*
$.ajax({
type: "POST",
url: "client-home2.aspx/downloadAttachment",
data: '{id:''' + id + '''}',
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function (msg) {
//alert(msg.d);
}
});
*/
$.download('client-home2.aspx/downloadAttachment', 'id=' + id);
return false;
});
我正在使用此功能http://filamentgroup.com/lab/jquery_plugin_for_requesting_ajax_like_file_downloads/
问题是，它从来没有给我文件；它只是导航到CCD_ 1。
如何解决此问题以便下载文件？
谢谢。
每个WebMethod调用只能发送一个HTTP响应。这意味着一次只能有一个文件。使用Response.End()可以阻止任何其他内容返回到web浏览器，并且很可能在foreach循环中第二次抛出异常。唯一的解决方法是从jQuery代码中调用WebMethod 20次，并有一个参数来知道如果查询中有多个结果，每次返回哪个文件。即使这样也可能行不通。
但我怀疑您真的打算让ID字段只产生一条记录。在这种情况下，你需要意识到两件事。第一种是，当您更改CommandText属性时，SqlCommand类型会重置其Parameters集合。因此，在添加ID参数之前，您需要完成整个sql字符串文本的创建。第二，您的ID参数现在根本不重要，因为您的sql代码从不引用该参数。
我很犹豫是否发布此代码，因为还有其他可能出错的地方，但这应该是对现有代码的改进。注意，我最终也做了同样的工作，但使用了更少的代码:
[WebMethod]
public void downloadAttachment(string id)
{
string SQL =
"select top 1 FILENAME, FILE_MIME_TYPE, ATTACHMENT" + ControlChars.CrLf
+ " FROM vwATTACHMENTS_CONTENT" + ControlChars.CrLf
+ " where ID = @ATTACHMENT_ID" + ControlChars.CrLf
+ " order by DATE_ENTERED desc";
//Debug.Print(SQL);
DbProviderFactory dbf = DbProviderFactories.GetFactory();
using (IDbConnection con = dbf.CreateConnection())
using (IDbCommand cmd = con.CreateCommand())
{
cmd.CommandText = SQL;
Sql.AppendParameter(cmd, id, "ATTACHMENT_ID");
using (IDataReader rdr = cmd.ExecuteReader())
{
if (rdr.Read())
{
// Send the file to the browser
Response.AddHeader("Content-type", r["FILE_MIME_TYPE"].ToString());
Response.AddHeader("Content-Disposition", "attachment; filename=" + r["FILENAME"].ToString());
Response.BinaryWrite((Byte[])r["ATTACHMENT"]);
Response.Flush();
Context.ApplicationInstance.CompleteRequest();
}
}
}
}
以下是我过去的做法，但我的做法有所不同：
视图：
foreach (var file in foo.Uploads)
{
<tr>
<td>@Html.ActionLink(file.Filename ?? "(no filename)", "Download", "Upload", new { id = file.UploadId }, null)</td>
</tr>
}
我的UploadConroller:中的代码隐藏
public ActionResult Download(Guid id)
{
var upload = this.GetUpload(id);
if (upload == null)
{
return NotFound();
}
return File(upload.Data, upload.ContentType, upload.Filename);
}
private Upload GetUpload(Guid id)
{
return (from u in this.DB.Uploads
where u.UploadId == id
select u).SingleOrDefault();
}
请随意货运邪教，这很简单。
我想明白了。我不得不制作一个单独的文件，因为邮件头已经在发送了。因此，我的单独文件被称为"downloadAttachment"，看起来像这样：
using System;
using System.Data;
using System.Data.Common;
using System.Configuration;
using System.Drawing;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Xml;
using System.Globalization;
using System.Threading;
using System.Diagnostics;
using System.Net;
using System.Net.Mail;
using System.Data.SqlClient;
using System.Web.Services;
using System.Text;
using System.Web.Script.Services;
using System.Text.RegularExpressions;
using System.IO;
namespace SplendidCRM.WebForms
{
public partial class downloadAttachment : System.Web.UI.Page
{
string HostedSite;
protected DataView vwMain;
protected void Page_Load(object sender, EventArgs e)
{
if (Sql.IsEmptyGuid(Security.USER_ID))
Response.Redirect("~/Webforms/client-login.aspx");
HostedSite = Sql.ToString(HttpContext.Current.Application["Config.hostedsite"]);
string id = Request.QueryString["ID"].ToString();
DbProviderFactory dbf = DbProviderFactories.GetFactory();
using (IDbConnection con = dbf.CreateConnection())
{
string sSQL;
sSQL = "select top 1 " + ControlChars.CrLf
+ " FILENAME, FILE_MIME_TYPE, ATTACHMENT" + ControlChars.CrLf
+ " from vwATTACHMENTS_CONTENT" + ControlChars.CrLf
+ " where 1 = 1 " + ControlChars.CrLf;
//Debug.Print(sSQL);
using (IDbCommand cmd = con.CreateCommand())
{
cmd.CommandText = sSQL;
Sql.AppendParameter(cmd, id.ToString(), "ATTACHMENT_ID");
cmd.CommandText += " order by DATE_ENTERED desc" + ControlChars.CrLf;
using (DbDataAdapter da = dbf.CreateDataAdapter())
{
((IDbDataAdapter)da).SelectCommand = cmd;
using (DataTable dt = new DataTable())
{
da.Fill(dt);
if (dt.Rows.Count > 0)
{
foreach (DataRow r in dt.Rows)
{
string name = (string)r["FILENAME"];
string contentType = (string)r["FILE_MIME_TYPE"];
Byte[] data = (Byte[])r["ATTACHMENT"];
// Send the file to the browser
Response.AddHeader("Content-type", contentType);
Response.AddHeader("Content-Disposition", "attachment; filename=" + MakeValidFileName(name));
Response.BinaryWrite(data);
Response.Flush();
Response.End();
}
}
else
{
}
}
}
}
}
}
public static string MakeValidFileName(string name)
{
string invalidChars = Regex.Escape(new string(System.IO.Path.GetInvalidFileNameChars()));
string invalidReStr = string.Format(@"[{0}]+", invalidChars);
string replace = Regex.Replace(name, invalidReStr, "_").Replace(";", "").Replace(",", "");
return replace;
}
}
}