blocks|key|1050960|text|文件是否正在上载到MVC应用程序？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1050961|public+ActionResult+FileUploader(HttpPostedFileBase+upload)
{
++string+mimeType=upload.ContentType;
}|code-block|syntax|javascript|1050962|不过，对于这一点有几个警告。|1050963|它使用浏览器提供的又名“客户端提供”的mime类型，如果上传项目的用户没有经过身份验证或信任，那么这可能不是一个好主意。|1050964|此外，IE并不总是为某些文件提供标准的Mime类型，特别是PNG(请参阅What+is+the+difference+between+"image/png"+and+"image/x-png"?)，这可能会也可能不会影响您的应用程序。|offset|length|1050965|我们只需使用一个简单的if语句将IE+png+mime类型(image/x-png)转换回更常见的类型(image/png)。|1050966|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/2086374/what-is-the-difference-between-image-png-and-image-x-png^0|0|0|0|0|10|1P|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|10|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|11|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|12|8|@]|9|@$M|13|N|14|1|15]]|A|$]]|$1|O|3|P|5|6|7|16|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|17|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]]]

Is the file being uploaded to the MVC application? 

<pre><code>public ActionResult FileUploader(HttpPostedFileBase upload)
{
 string mimeType=upload.ContentType;
}
</code></pre>

There are a couple of caveats with this though.

It uses the browser supplied aka 'client supplied' mime type, if the users uploading items aren't authenticated or trusted, then this might not be a good idea.

Also IE doesn't always give standard Mime types for certain files, in particular PNGs (see <a href="https://stackoverflow.com/questions/2086374/what-is-the-difference-between-image-png-and-image-x-png">What is the difference between &quot;image/png&quot; and &quot;image/x-png&quot;?</a>) which may or may not effect your application.

We just use a simple if statement to convert the IE png mime type (image/x-png), back to the more common one (image/png).

blocks|key|1051043|text|想法:将格式和扩展数据(http://www.feedforall.com/mime-types.htm)以字典、数组或其他形式放入xml或项目中进行查询，并创建一个确定扩展的mimetype的过程。我认为将你的数据保存在xml文档中会更容易在编译后进行修改|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1051044|entityMap|0|LINK|mutability|MUTABLE|url|http://www.feedforall.com/mime-types.htm^0|C|14|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

IDEA: put the formats and extensions data (<a href="http://www.feedforall.com/mime-types.htm" rel="noreferrer">http://www.feedforall.com/mime-types.htm</a>) into an xml or into your project as dictionary, array or sth else for query and create a procedure for determine mimetype for extension.. i think keeping your data on xml document will be easier for modification after compiling

blocks|key|836354|text|在.Net+4.5中，您可以使用MimeMapping.GetMimeMapping|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|836355|string+contentType+=+MimeMapping.GetMimeMapping("someFileName.pdf")
//+contentType+=+"application/pdf"|code-block|syntax|javascript|836356|More+information|836357|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.microsoft.com/en-us/dotnet/api/system.web.mimemapping.getmimemapping|1|http://blogs.msdn.com/b/webdev/archive/2013/02/14/getting-a-mime-type-from-a-file-extension-in-asp-net-4-5.aspx^0|G|Q|G|Q|0|0|0|0|G|1|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|F|3|G|5|H|7|12|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|13|8|@]|D|@$9|14|A|15|1|16]]|E|$]]|$1|M|3|-4|5|6|7|17|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]|U|$5|P|Q|R|E|$S|V]]]]

In .Net 4.5 you can use <a href="https://docs.microsoft.com/en-us/dotnet/api/system.web.mimemapping.getmimemapping" rel="noreferrer"><code>MimeMapping.GetMimeMapping</code></a>:

<pre><code>string contentType = MimeMapping.GetMimeMapping("someFileName.pdf")
// contentType = "application/pdf"
</code></pre>

<a href="http://blogs.msdn.com/b/webdev/archive/2013/02/14/getting-a-mime-type-from-a-file-extension-in-asp-net-4-5.aspx" rel="noreferrer">More information</a>

blocks|key|836365|text|如果要使用stream|type|unstyled|depth|inlineStyleRanges|entityRanges|data|836366|++++public+class+urlmonMimeDetect
++++{
++++++++[DllImport(@"urlmon.dll",+CharSet+=+CharSet.Auto)]
++++++++private+extern+static+System.UInt32+FindMimeFromData(
++++++++++++System.UInt32+pBC,
++++++++++++[MarshalAs(UnmanagedType.LPStr)]+System.String+pwzUrl,
++++++++++++[MarshalAs(UnmanagedType.LPArray)]+byte[]+pBuffer,
++++++++++++System.UInt32+cbSize,
++++++++++++[MarshalAs(UnmanagedType.LPStr)]+System.String+pwzMimeProposed,
++++++++++++System.UInt32+dwMimeFlags,
++++++++++++out+System.UInt32+ppwzMimeOut,
++++++++++++System.UInt32+dwReserverd
++++++++);

++++++++public+static+string+GetMimeFromFile(Stream+fs)
++++++++{

++++++++++++byte[]+buffer+=+new+byte[256];
++++++++++++fs.Read(buffer,+0,+256);

++++++++++++try
++++++++++++{
++++++++++++++++System.UInt32+mimetype;
++++++++++++++++FindMimeFromData(0,+null,+buffer,+256,+null,+0,+out+mimetype,+0);
++++++++++++++++System.IntPtr+mimeTypePtr+=+new+IntPtr(mimetype);
++++++++++++++++string+mime+=+Marshal.PtrToStringUni(mimeTypePtr);
++++++++++++++++Marshal.FreeCoTaskMem(mimeTypePtr);
++++++++++++++++return+mime;
++++++++++++}
++++++++++++catch+(Exception+e)
++++++++++++{
++++++++++++++++return+"unknown/unknown";
++++++++++++}
++++++++}
++++}|code-block|syntax|javascript|836367|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you want to use stream

<pre><code> public class urlmonMimeDetect
 {
 [DllImport(@"urlmon.dll", CharSet = CharSet.Auto)]
 private extern static System.UInt32 FindMimeFromData(
 System.UInt32 pBC,
 [MarshalAs(UnmanagedType.LPStr)] System.String pwzUrl,
 [MarshalAs(UnmanagedType.LPArray)] byte[] pBuffer,
 System.UInt32 cbSize,
 [MarshalAs(UnmanagedType.LPStr)] System.String pwzMimeProposed,
 System.UInt32 dwMimeFlags,
 out System.UInt32 ppwzMimeOut,
 System.UInt32 dwReserverd
 );

 public static string GetMimeFromFile(Stream fs)
 {

 byte[] buffer = new byte[256];
 fs.Read(buffer, 0, 256);

 try
 {
 System.UInt32 mimetype;
 FindMimeFromData(0, null, buffer, 256, null, 0, out mimetype, 0);
 System.IntPtr mimeTypePtr = new IntPtr(mimetype);
 string mime = Marshal.PtrToStringUni(mimeTypePtr);
 Marshal.FreeCoTaskMem(mimeTypePtr);
 return mime;
 }
 catch (Exception e)
 {
 return "unknown/unknown";
 }
 }
 }
</code></pre>

I am trying to determine dynamically the content/type of a input file. If I would be in a windows application I could write code like this (<a href="http://codeasp.net/blogs/raghav_khunger/microsoft-net/531/how-to-get-content-type-of-a-file-in-c" rel="noreferrer">from this blog</a>)

<pre><code>private string GetContentType(string fileName) {
 string contentType = "application/octetstream";
 string ext = System.IO.Path.GetExtension(fileName).ToLower();
 Microsoft.Win32.RegistryKey registryKey = Microsoft.Win32.Registry.ClassesRoot.OpenSubKey(ext);
 if (registryKey != null &amp;&amp; registryKey.GetValue("Content Type") != null)
 contentType = registryKey.GetValue("Content Type").ToString();
 return contentType;
} 
</code></pre>

What other methods are more suitable for an MVC application? 

I would like to use the param within the <code>Controller.File(...)</code> method that receive a filepath and a contentype.

How to get the content/type of a file at runtime

我正在尝试动态确定输入文件的内容/类型。如果我在windows应用程序中，我可以像这样写代码()private string GetContentType(string fileName) {    string contentType = "application/octetstream";    string ex...

问如何在运行时获取文件的内容/类型
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