Question

我修改了一个文件上传项目＆amp;下载到＆amp;从SQL服务器使用C＃按照我的要求添加三个文本框。我能够在SQL服务器上传文件，并可以使用以下页面查看文件

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">

  <title>Uploaded Files</title>
</head>
<body>
  <form id="form1" runat="server">
    <div>
      <asp:GridView ID="GridView1" runat="server"   AutoGenerateColumns="False" DataSourceID="odsFiles" OnRowDataBound="GridView1_RowDataBound">
        <Columns>
          <asp:BoundField DataField="Id" HeaderText="Id" SortExpression="Id" />
          <asp:BoundField DataField="OriginalName" HeaderText="OriginalName" SortExpression="OriginalName" />
          <asp:BoundField DataField="ContentType" HeaderText="ContentType" SortExpression="ContentType" />
          <asp:BoundField DataField="DateCreated" HeaderText="DateCreated" SortExpression="DateCreated" />
          <asp:BoundField DataField="Equipment" HeaderText="Equipment" SortExpression="Equipment" />
          <asp:BoundField DataField="Uploadedby" HeaderText="Uploaded by" SortExpression="Uploadedby" />
          <asp:BoundField DataField="Letter_date" HeaderText="Letter Dated" SortExpression="Letter_date" />
          <asp:HyperLinkField DataNavigateUrlFields="Id" DataNavigateUrlFormatString="~/DownloadFile.aspx?Id={0}" HeaderText="Download" Text="Download" />
          <asp:TemplateField HeaderText="View">
            <ItemTemplate>
              <asp:HyperLink ID="lnkView" runat="server" NavigateUrl='<%# Eval("Id", "~/ViewFile.aspx?Id={0}") %>' Text="View"></asp:HyperLink>
            </ItemTemplate>
          </asp:TemplateField>
        </Columns>
      </asp:GridView>
      <br />
      <br />
      <asp:Button ID="btnAddNew" runat="server" OnClick="btnAddNew_Click" Text="Add New File" /><br />
      <br />
      <br />
      <asp:ObjectDataSource ID="odsFiles" runat="server" SelectMethod="GetList" TypeName="FileInfo" />
    </div>
  </form>
</body>
</html>

这没有问题，我无法修改项目的下载部分，因为最初项目是使用Id = uniqueidentifier开发的，我已将其更改为Int。此文件中的Perhapes问题（downloadfile.aspx.cs）：

using System;
using System.IO;

public partial class DownloadFile : System.Web.UI.Page
{
  protected void Page_Load(object sender, EventArgs e)
  {
    if (Request.QueryString.Get("Id") != null)
    {
      Response.Clear();

      int id = new int(Request.QueryString.Get("Id"));
      File myFile = File.GetItem(id);

      Response.ContentType = "application/x-unknown";
      Response.AppendHeader("Content-Disposition", "attachment; filename=\"" + myFile.OriginalName + "\"");
      if (myFile.ContainsFile)
      {
        Response.BinaryWrite(myFile.FileData);
      }
      else
      {
        Response.WriteFile(Path.Combine(AppConfiguration.UploadsFolder, myFile.FileUrl));
      }
    }
    else
    {
      Response.Redirect("~/");
    }
  }
}

第二个文件（File.cs）如下：

using System;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.IO;

/// <summary>
/// The File class abstracts behavior for uploaded files that are stored in a datastore.
/// It allows you to save an uploaded file in the datastore and retrieve it again.
/// </summary>
[DataObject()]
public class File
{

  #region Private Variables

  private Int32 id;
  private string fileUrl;
  private byte[] fileData;
  private string contentType;
  private string originalName;
  private DateTime dateCreated;
  private bool containsFile;

  #endregion

  #region Public Properties

  /// <summary>
  /// Gets the unique id of the uploaded file.
  /// This ID is used as the file name when files are stored in the file system.
  /// </summary>
  public Int32 Id
  {
    get
    {
      return id;
    }
  }

  /// <summary>
  /// Gets the date and time the file was uploaded.
  /// </summary>
  public DateTime DateCreated
  {
    get
    {
      return dateCreated;
    }
  }

  /// <summary>
  /// Gets the content type of the file.
  /// </summary>
  public string ContentType
  {
    get
    {
      return contentType;
    }
  }

  /// <summary>
  /// Gets the original name of the file.
  /// </summary>
  public string OriginalName
  {
    get
    {
      return originalName;
    }
  }

  /// <summary>
  /// Gets the virtual URL of the file.
  /// When this property does not contain data, then <see cref="FileData"/> contains
  /// a byte array with the actual file.
  /// </summary>
  public string FileUrl
  {
    get
    {
      return fileUrl;
    }
  }

  /// <summary>
  /// Gets the file data.
  /// When this property does not contain data, then <see cref="FileUrl"/> contains
  /// the virtual path to the file starting from the Uploads folder.
  /// </summary>
  public byte[] FileData
  {
    get
    {
      return fileData;
    }
  }

  /// <summary>
  /// Gets a value indicating whether this instance contains the actual file data.
  /// When ContainsFile is true, it means the actual file is held in <see cref="FileData"/>.
  /// When ContainsFile is false, then <see cref="FileUrl"/> contains the virtual path
  /// to the file on disk.
  /// </summary>
  public bool ContainsFile
  {
    get
    {
      return containsFile;
    }
  }

  #endregion

  #region Public Methods

  /// <summary>
  /// Gets a file from the datastore.
  /// </summary>
  /// <param name="fileId">The ID of the file.</param>
  public static File GetItem(Guid fileId)
  {
    File myFile = null;
    using (SqlConnection mySqlConnection = new SqlConnection(AppConfiguration.ConnectionString))
    {
      SqlCommand myCommand = new SqlCommand("sprocFilesSelectSingleItem", mySqlConnection);
      myCommand.CommandType = CommandType.StoredProcedure;

      SqlParameter prmId = new SqlParameter("@id", SqlDbType.Int);
      prmId.Value = fileId;
      myCommand.Parameters.Add(prmId);

      mySqlConnection.Open();
      using (SqlDataReader myReader = myCommand.ExecuteReader())
      {
        if (myReader.Read())
        {
          myFile = new File(myReader);
        }
        myReader.Close();
      }
      mySqlConnection.Close();
    }
    return myFile;
  }

  /// <summary>
  /// Saves a file to the database.
  /// </summary>
  /// <returns>Returns true when the file was stored succesfully, or false otherwise.</returns>
  public bool Save()
  {
    return Save(DataStoreType.Database, String.Empty);
  }

  /// <summary>
  /// Saves a file to the file system.
  /// This method also saves the meta data of the file to the database.
  /// </summary>
  /// <param name="filePath">The location and name of the file that is to be saved.</param>
  /// <returns>
  /// Returns true when the file was stored succesfully, or false otherwise.
  /// </returns>
  public bool Save(string filePath)
  {
    return Save(DataStoreType.FileSystem, filePath);
  }

  /// <summary>
  /// Saves a file to the database and optionally to disk.
  /// </summary>
  /// <returns>Returns true when the file was stored succesfully, or false otherwise.</returns>
  private bool Save(DataStoreType dataStoreType, string filePath)
  {
    using (SqlConnection mySqlConnection = new SqlConnection(AppConfiguration.ConnectionString))
    {
      // Set up the Command object
      SqlCommand myCommand = new SqlCommand("sprocFilesInsertSingleItem", mySqlConnection);
      myCommand.CommandType = CommandType.StoredProcedure;

      // Set up the ID parameter
      SqlParameter prmId = new SqlParameter("@id", SqlDbType.Int);

      prmId.Value = id;
      myCommand.Parameters.Add(prmId);

      // Set up the FileUrl parameter
      SqlParameter prmFileUrl = new SqlParameter("@fileUrl", SqlDbType.NVarChar, 255);

      // If we need to store the file on disk, save the fileUrl.
      if (dataStoreType == DataStoreType.FileSystem)
      {
        prmFileUrl.Value = fileUrl;
      }
      else
      {
        prmFileUrl.Value = DBNull.Value;
      }
      myCommand.Parameters.Add(prmFileUrl);

      // Set up the FileData parameter
      SqlParameter prmFileData = new SqlParameter("@fileData ", SqlDbType.VarBinary);

      // If we need to store the file in the database, 
      // pass in the actual file bytes.
      if (dataStoreType == DataStoreType.Database)
      {
        prmFileData.Value = fileData;
        prmFileData.Size = fileData.Length;
      }
      else
      {
        prmFileData.Value = DBNull.Value;
      }
      myCommand.Parameters.Add(prmFileData);

      // Set up the OriginalName parameter
      SqlParameter prmOriginalName = new SqlParameter("@originalName", SqlDbType.NVarChar, 50);
      prmOriginalName.Value = originalName;
      myCommand.Parameters.Add(prmOriginalName);

      // Set up the ContentType parameter
      SqlParameter prmContentType = new SqlParameter("@contentType", SqlDbType.NVarChar, 50);
      prmContentType.Value = contentType;
      myCommand.Parameters.Add(prmContentType);

      // Execute the command, and clean up.
      mySqlConnection.Open();
      bool result = myCommand.ExecuteNonQuery() > 0;
      mySqlConnection.Close();

      // Database update is done; now store the file on disk if we need to.
      if (dataStoreType == DataStoreType.FileSystem)
      {
        const int myBufferSize = 1024;
        Stream myInputStream = new MemoryStream(fileData);
        Stream myOutputStream = System.IO.File.OpenWrite(filePath);

        byte[] buffer = new Byte[myBufferSize];
        int numbytes;
        while ((numbytes = myInputStream.Read(buffer, 0, myBufferSize)) > 0)
        {
          myOutputStream.Write(buffer, 0, numbytes);
        }
        myInputStream.Close();
        myOutputStream.Close();
      }

      return result;
    }
  }
  #endregion

  #region Constructor(s)

  /// <summary>
  /// Initializes a new instance of the <see cref="File"/> class with the data from the SqlDataReader.
  /// </summary>
  /// <param name="myReader">A SqlDataReader that contains the data for this file.</param>
  public File(SqlDataReader myReader)
  {
      id = myReader.Int32(myReader.GetOrdinal("Id"));
    dateCreated = myReader.GetDateTime(myReader.GetOrdinal("DateCreated"));
    originalName = myReader.GetString(myReader.GetOrdinal("OriginalName"));
    contentType = myReader.GetString(myReader.GetOrdinal("ContentType"));

    if (!myReader.IsDBNull(myReader.GetOrdinal("FileData")))
    {
      fileData = (byte[])myReader[myReader.GetOrdinal("FileData")];
      containsFile = true;
    }
    else
    {
      fileUrl = myReader.GetString(myReader.GetOrdinal("FileUrl"));
      containsFile = false;
    }
  }

  /// <summary>
  /// Initializes a new instance of the File class with the data from the incoming parameters.
  /// </summary>
  /// <param name="contentType">The content type of the file, like image/pjpeg or image/gif.</param>
  /// <param name="originalName">The original name of the uploaded file.</param>
  /// <param name="fileData">A byte array with the actual file data.</param>
  public File(string contentType, string originalName, byte[] fileData)
  {
      this.id = Convert.ToInt32;
    this.contentType = contentType;
    this.fileData = fileData;
    this.originalName = originalName;

    string extension = Path.GetExtension(originalName);
    string fileName = this.Id.ToString() + extension;
    this.fileUrl = fileName;
  }

  #endregion

}

我收到错误＆＃34;编译器错误消息：CS1061：＆＃39; System.Data.SqlClient.SqlDataReader＆＃39;不包含＆＃39; Int32＆＃39;的定义没有扩展方法＆＃39; Int32＆＃39;接受类型＆System; System.Data.SqlClient.SqlDataReader＆＃39;的第一个参数。可以找到（你是否错过了使用指令或汇编引用？）＆＃34;在＆＃39; File.cs＆＃39;。请帮忙。

Answer 1

变化： -

id = myReader.Int32(myReader.GetOrdinal("Id"));

到

id = myReader.GetInt32(myReader.GetOrdinal("Id"));

在File构造函数中，SqlDataReader不包含Int32的定义，您的异常消息是不言自明的。

Answer 2

试试这个

    int index;
    if (_sqlreader.HasRows)
    {
      index = _sqlreader.GetOrdinal("ColumnName");
      if (!_sqlreader.IsDBNull(index))
        return _sqlreader.GetInt32(index);
    }

使用C＃从SQL Server下载文件

2 个答案: