在asp.net中显示来自二进制数据/ Blob的图像

Question

我设法使用imagehandler从数据库中检索了我的图像，但是问题是，它仅使用第一个图像检索，而不是在不同的数据上显示不同的图像。

所以这是我的图像处理程序代码，我对此行有string volunteerNames = imageRequest.QueryString["VolunteerName"]; （ string volunteerNames = imageRequest.QueryString["VolunteerName"]; ），其中仅显示System.Byte[]而不显示名称

<%@ WebHandler Language="C#" Class=".ShowImage" %>

using System;
using System.Web;
using System.Configuration;
using System.Data.SqlClient;

public class ShowImage : IHttpHandler
{

public void ProcessRequest(HttpContext context)
{
    HttpRequest imageRequest = context.Request;
    HttpResponse imageResponse = context.Response;


    //string connStr = ConfigurationManager.ConnectionStrings["DBconnStr"].ConnectionString;
    using (SqlConnection conn = new SqlConnection())
    {
        conn.ConnectionString = "Data Source=.\\SQLEXPRESS;AttachDbFilename=\"C:\\Users\\User\\Desktop\\ProjectAV2.9\\ProjectA\\ProjectA\\App_Data\\ProjectA.mdf\";Integrated Security=True;Connect Timeout=30;User Instance=True";
        string queryStr = "SELECT * FROM TVolunteer WHERE VolunteerName = @Name";
        string bQueryStr = "SELECT * FROM BVolunteer WHERE VolunteerName = @Name";
        string volunteerNames = imageRequest.QueryString["VolunteerName"];

        SqlCommand bCMD = new SqlCommand(bQueryStr, conn);
        SqlCommand cmd = new SqlCommand(queryStr, conn);
        bCMD.Parameters.AddWithValue("@Name", volunteerNames);
        cmd.Parameters.AddWithValue("@Name", volunteerNames);
        conn.Open();

        SqlDataReader dr = cmd.ExecuteReader();


        if (dr.HasRows)
        {
            dr.Read();
            string volunteerNRIC = dr["VolunteerNRIC"].ToString();
            byte[] volunteerProfilePicture = (byte[])dr["VolunteerProfilePicture"];
            string volunteerName = dr["VolunteerName"].ToString();
            string volunteerContact = dr["VolunteerContact"].ToString();
            string volunteerAddress = dr["VolunteerAddress"].ToString();
            string volunteerEmail = dr["VolunteerEmail"].ToString();
            imageResponse.BinaryWrite(volunteerProfilePicture);

        }
        dr.Close();

        SqlDataReader bDR = bCMD.ExecuteReader();
        if (bDR.HasRows)
        {
            bDR.Read();
            byte[] volunteerProfilePicture = (byte[])bDR["VolunteerProfilePicture"];
            string volunteerName = bDR["VolunteerName"].ToString();
            string volunteerContact = bDR["VolunteerContact"].ToString();
            string volunteerAddress = bDR["VolunteerAddress"].ToString();
            string volunteerEmail = bDR["VolunteerEmail"].ToString();
            imageResponse.BinaryWrite(volunteerProfilePicture);

            bDR.Close();
        }
    }
}

 public bool IsReusable
 {
    get
    {
        return false;
    }

 }
}

这是我的数据列表

  <asp:DataList ID="dl_tvolunteer" runat="server" CellPadding="3" 
        ForeColor="#333333" RepeatColumns="3"
    RepeatDirection="Horizontal" Width="375px" Height="193px" GridLines="Both">
        <ItemTemplate>
            <asp:Image ID="Image1" runat="server" ImageUrl='<%# DataBinder.Eval(Container.DataItem, "VolunteerProfilePicture","~/ShowImage.ashx?VolunteerName="+ Eval("VolunteerName") %>'  />
            <br />
            <asp:Label ID="lbl_Name" runat="server" Text='<%# Bind("VolunteerName") %>'></asp:Label>
            <br />
            <asp:Label ID="lbl_Contact" runat="server" Text='<%# Bind("VolunteerContact") %>'></asp:Label>
            <br />
            <asp:Label ID="lbl_Address" runat="server" Text='<%# Bind("VolunteerAddress") %>'></asp:Label>
            <br />
            <asp:Label ID="lbl_Email" runat="server" Text='<%# Bind("VolunteerEmail") %>'></asp:Label>
        </ItemTemplate>
    </asp:DataList>

Answer 1

您应该像这样在图像处理程序中定义mime类型：

imageResponse.ContentType = "Image/Jpeg";

编辑：似乎您应该像这样更改图像列。 那将获得您的志愿者名称，并将其传递给您的查询字符串参数：

<asp:Image ID="Image1" runat="server" ImageUrl='<%# 
       DataBinder.Eval(Container.DataItem, 
                       "VolunteerName", 
                       "~/ShowImage.ashx?VolunteerName={0}") 
       %>'/>