如何通过c＃asp.net中的按钮单击事件在图像字段中显示图像

Question

我在更改图片字段的imageUrl时遇到问题。我想通过单击名为“upload”的按钮来显示上传的图像。 这是我的服务器端代码：

if (fileUpload.HasFile)
{           Directory.CreateDirectory(HttpContext.Current.Server.MapPath("~/uploads/logo"));
            string targetFolder = HttpContext.Current.Server.MapPath("~/uploads/logo");
            string targetPath = Path.Combine(targetFolder, "photo.png");
            fileUpload.SaveAs(targetPath);
            employeeImage.ImageUrl = targetPath;
}

Answer 1

我通过使用webhandler（.ashx）来解决这个问题。

public class   ImageHandler:IHttpHandler,System.Web.SessionState.IRequiresSessionState

{

  public void ProcessRequest (HttpContext context) {
    //Checking whether the imagebytes variable have anything else not doin anything
    if ((context.Session["ImageBytes"]) != null)
    {
        byte[] image = (byte[])(context.Session["ImageBytes"]);
        context.Response.ContentType = "image/JPEG";
        context.Response.BinaryWrite(image);
    }
}

public bool IsReusable {
    get {
        return false;
    }
}

}

和服务器端代码是：

protected void uploadButton_Click(object sender, EventArgs e)
{
    Session["ImageBytes"] = fileUpload.FileBytes;
    employeeImage.ImageUrl = "~/ImageHandler.ashx";
}