调用Graphics.DrawImage时出现SecurityException

本文关键字：SecurityException Graphics DrawImage 调用 | 更新日期: 2023-09-27 18:23:35

我正在部署一个将图像存储在数据库中的MVC3应用程序。要求是执行GET以从数据库中检索图像，然后将图像写入响应流。当地一切都很好（当然）。

我正在使用共享主机提供商（是的，没有完全信任，<trust>被阻止）。我正在使用此ImageResult返回图像：

public override void ExecuteResult(ControllerContext context)
        {
            using (Bitmap bitmap = new Bitmap(width, height))
            {
                using (Graphics graphics = Graphics.FromImage(bitmap))
                {
                    Rectangle displayRectangle = new Rectangle(new Point(0, 0), new Size(width - 1, height - 1));
                    graphics.DrawImage(Image.FromHbitmap(_imageBitmap.GetHbitmap()), 0, 0);
                    context.HttpContext.Response.ContentType = "image/jpg";
                    bitmap.Save(context.HttpContext.Response.OutputStream, ImageFormat.Jpeg);
                }
            }
        }

我已经追踪到了我呼叫graphics.DrawImage()的线路上的错误。这是堆栈：

System.Security.SecurityException: Request for the permission of type 'System.Security.Permissions.SecurityPermission, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.
   at TM.Web.ImageResult.ExecuteResult(ControllerContext context)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19()
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation)
   at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<>c__DisplayClass1e.<InvokeActionResultWithFilters>b__1b()
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)
   at System.Web.Mvc.Controller.ExecuteCore()
   at System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext)
   at System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext)
   at System.Web.Mvc.MvcHandler.<>c__DisplayClass6.<>c__DisplayClassb.<BeginProcessRequest>b__5()
   at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass1.<MakeVoidDelegate>b__0()
   at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.End()
   at System.Web.Mvc.MvcHandler.<>c__DisplayClasse.<EndProcessRequest>b__d()
   at System.Web.Mvc.SecurityUtil.<GetCallInAppTrustThunk>b__0(Action f)
   at System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Action action)
   at System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult)
   at System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result)
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
The action that failed was:
LinkDemand
The type of the first permission that failed was:
System.Security.Permissions.SecurityPermission

我也知道在网络上使用GDI+并不完全受支持。有更好的方法吗？或者至少是一种不会绊倒部分信托的方式？非常感谢。

调用Graphics.DrawImage时出现SecurityException

事实证明，我把这件事复杂化了。我发现了这篇很好的文章，解释了为什么我不能将位图从数据库保存到输出流。

这让我尝试取消GDI+调用。我最终得到了一个效果很好的（_imageBitmap已从数据库中提取）：

public override void ExecuteResult(ControllerContext context)
{
    using (Bitmap bitmap = new Bitmap(_imageBitmap))
    {
            context.HttpContext.Response.ContentType = "image/jpg";
            bitmap.Save(context.HttpContext.Response.OutputStream, ImageFormat.Jpeg);
    }
}