I want to invent a new mime-type and associate it to a custom application in the browser to enable users to launch my app from a web page. The users of my secure web site are in a closed-environment, meaning this is not a general-purpose, mainstream application - I can configure their browser ahead of time.
Spoon.net does something very similar to enable launching virtualized applications using their mini-kernel plugin.
One of the answers to this question alluded to this method, without details for how to accomplish it.
How do I achieve this in a cross-platform manner on Chrome and IE 8/9? Is there a way to do the mime-type association through browser extensions, either native or through crossrider? How does an app like Adobe Reader or Apple Quicktime achieve this? I want to avoid touching the registry if possible.
What are the risks associated with this method? My site is an intranet web application secured with a certificate and trusted by my users. Any reason I should not go down this path?
EDIT: Apparently this can be achieved in Firefox by manipulating the mimeTypes.rdf file.
EDIT: It looks like JDIC is a Java-based mechanism that could be used for the same thing. Is there a similar non-Java construct? Maybe in Javascript?
It looks like it can be done via a registry change on windows.
[HKEY_CLASSES_ROOT\.atom]
    @="atom_file"
[HKEY_CLASSES_ROOT\atom_file]
    @="Atom Syndication Program"
[HKEY_CLASSES_ROOT\atom_file\shell]
[HKEY_CLASSES_ROOT\atom_file\shell\open]
[HKEY_CLASSES_ROOT\atom_file\shell\open\command]
    @="\"C:\\AtomHandler\\handle.exe\" %1"
[HKEY_CLASSES_ROOT\MIME\Database\Content Type\application/atom+xml]
    "Extension"=".atom"
Further reading on Windows...
And here's how to do so on Linux.
Use xdg-utils from freedesktop.org Portland
I often want to associate a new file type with being a text file. The safest and quickest way of doing this is:
A. Create the file type in Registry if it doesn't already exist
- Windows -> Search for RegistryEditor -> Open
 - Right-Click HKEY_CLASSES_ROOT -> New -> Key
 - Name the key the same as the extension (e.g. .txttt)
 - Click on the newly created key (e.g. HKEY_CLASSES_ROOT -> .txttt) -> Right-click on (Default) in the right pane -> Modify -> Set to the following values:
 
(Default) REGSZ txtfile
- Right-click on the newly created key (e.g. HKEY_CLASSES_ROOT -> .txttt) -> New -> String -> Set to the following values:
 
ContentType REG_SZ text/plain
- Right-click on the newly created key (e.g. HKEY_CLASSES_ROOT -> .txttt) -> New -> String -> Set to the following values:
 
PerceivedType REG_SZ text
B. Associate the file type with a default program
- Right-click on your file -> Open with -> Choose another app
 - Check "Always use to open with this program"
 - Select the default program
 
The new file type should open and preview in Windows Explorer with the default text editor program you selected.
来源:https://stackoverflow.com/questions/6267546/how-do-i-associate-a-custom-mime-type-to-my-local-application-in-the-major-brows