如何在不使用文件路径的情况下从GridView中的数据库中退休图像

Question

我有一个模块将文件上传到我的sqlserver数据库中，其中我的字段如fname：for fileName，contentType，contentType：for for Filetype的nvarchar和数据：varbinary：varbinary for for MATEAS数据。因此，现在我能够使用仅显示我上传的文件名的BoundField在GridView中对其进行检验，但是我实际想要的是从数据库中识别文件，如果它是图像文件，则应显示该图像在GridView中，如果是图像以外的文件，请让它仅显示文件名。请注意，我不想使用文件夹上传文件并使用文件路径来检索它。任何人都有类似的经验可以分享：

<asp:GridView ID="GridView1" runat="server" HeaderStyle-BackColor="#3AC0F2" HeaderStyle-ForeColor="White"
    RowStyle-BackColor="#A1DCF2" AlternatingRowStyle-BackColor="White" AlternatingRowStyle-ForeColor="#000"
    AutoGenerateColumns="false">
    <Columns>
        <asp:BoundField DataField="Name" HeaderText="File Name"/>
        <asp:TemplateField ItemStyle-HorizontalAlign = "Center">
            <ItemTemplate>
                <asp:LinkButton ID="lnkDownload" runat="server" Text="Download" OnClick="DownloadFile"
                    CommandArgument='<%# Eval("Id") %>'></asp:LinkButton>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

代码背后：

protected void Upload(object sender, EventArgs e)
{
    string filename = Path.GetFileName(FileUpload1.PostedFile.FileName);
    string contentType = FileUpload1.PostedFile.ContentType;
    using (Stream fs = FileUpload1.PostedFile.InputStream)
    {
        using (BinaryReader br = new BinaryReader(fs))
        {
            byte[] bytes = br.ReadBytes((Int32)fs.Length);
            string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
            using (SqlConnection con = new SqlConnection(constr))
            {
                string query = "insert into tblFiles values (@Name, @ContentType, @Data)";
                using (SqlCommand cmd = new SqlCommand(query))
                {
                    cmd.Connection = con;
                    cmd.Parameters.AddWithValue("@Name", filename);
                    cmd.Parameters.AddWithValue("@ContentType", contentType);
                    cmd.Parameters.AddWithValue("@Data", bytes);
                    con.Open();
                    cmd.ExecuteNonQuery();
                    con.Close();
                }
            }
        }
    }
}

Answer 1

您需要使用ContentType来决定如何显示数据

<asp:GridView ID="GridView1" runat="server" HeaderStyle-BackColor="#3AC0F2" HeaderStyle-ForeColor="White"
    RowStyle-BackColor="#A1DCF2" AlternatingRowStyle-BackColor="White" AlternatingRowStyle-ForeColor="#000" OnRowDataBound="GridView1_RowDataBound"
    AutoGenerateColumns="false">
    <Columns>
        <asp:BoundField DataField="Name" HeaderText="File Name"/>
        <asp:TemplateField ItemStyle-HorizontalAlign = "Center">
            <ItemTemplate>
                <asp:LinkButton ID="lnkDownload" runat="server" Text="Download" OnClick="DownloadFile"
                    CommandArgument='<%# Eval("Id") %>'></asp:LinkButton>
                <img runat="server" id="imgData" />
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

在"行数据"中，决定要做什么

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
            {
                if (e.Row.RowType == DataControlRowType.DataRow)
                {
                    LinkButton lnkButton = (LinkButton)e.Row.Cells[1].FindControl("lnkDownload");
                    HtmlImage img = (HtmlImage)e.Row.Cells[1].FindControl("imgData");
                    if (DataBinder.Eval(e.Row.DataItem, "ContentType").ToString().Contains("image"))//like image/jpeg
                    {
                        lnkButton.Visible = false;
                        img.Visible = true;
                        img.Src = "data:image/png;base64," + Convert.ToBase64String((byte[])DataBinder.Eval(e.Row.DataItem,"Data"));
                    }
                    else
                    {
                        lnkButton.Visible = true;
                        img.Visible = false;
                    }
                }
            }