无法从ASP.NET中的C：\读取图像 [英] Can't read images from C:\ in ASP.NET

问题描述

我意识到这是一个边缘情况，但似乎asp.net不允许从根驱动器读取图像。为了测试这个，我编写了以下非常简单的应用程序：

I realize this is an edge case, but it seems that asp.net doesn't allow reading images from the root drive. To test this I wrote the following very simple application:

在页面上我有：

<asp:Image ID="test" runat="server" />

在后面的代码中我有：

test.ImageUrl = @"C:\test\image.jpg";
test.AlternateText = File.ReadAllText(@"C:\test\text.txt");

两个文件都按照您的预期存在并具有正确的权限。查看页面源代码时，我们会看到如下所示的img标记：

Both files exist as you'd expect and have the correct permissions. When viewing the source of the page we get an img tag that looks like the following:

<img id="test" src="C:\test\image.jpg" alt="some text to read" style="border-width:0px;" /> 

当我在VS中运行时，不显示任何图像。如果我复制源，将其粘贴到html文件中并将其加载到浏览器中，显示图像。任何人都可以解释为什么会这样吗？

When I run this in VS no image is displayed. If I copy the source, paste it into an html file and load it into a browser the image is displayed. Can anybody explain why this is?

推荐答案

浏览器阻止显示图像。我创建了一个静态HTML页面，其中包含一个标签，其src指向我本地文件系统上的图像。如果我在本地打开HTML页面，一切都按预期工作。但是，当我在Web服务器中托管静态HTML页面时，它停止工作。

The browser is preventing the images from being displayed. I created a static HTML page containing an tag whose "src" pointed to an image on my local file system. If I open the HTML page locally, everything works as expected. However, when I hosted the static HTML page in a web server, it stopped working.

我从远程服务器和本地文件加载HTML页面时运行了ProcMon被访问（一些列被截断用于显示目的）：

I ran ProcMon while loading the HTML page from the remote server, and the local file was accessed (some columns truncated for display purposes):

iexplore.exe    6376    QueryDirectory  C:\test.jpg SUCCESS test.jpg
iexplore.exe    6376    QueryOpen   C:\test.jpg SUCCESS 
iexplore.exe    6376    QueryDirectory  C:\test.jpg SUCCESS 
iexplore.exe    6376    CreateFile  C:\test.jpg SUCCESS
iexplore.exe    6376    ReadFile    C:\test.jpg SUCCESS
iexplore.exe    6376    CloseFile   C:\test.jpg SUCCESS

然而，IE没有显示图像。我用Firefox重复测试。在本地访问时，ProcMon结果是相同的。远程访问时，ProcMon不会产生任何输出。

However, IE did not display the image. I repeated the test with Firefox. When accessing locally, the ProcMon results were the same. When accessing remotely, ProcMon didn't produce any output.

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