android - How to add custom mime type?

Question

What I want: To be able to send my custom file by mail and import it with my application from the preview button in GMail or when opening it in a file browser.

What I know: I've read a lot of custom mime type handlers, that android doesn't care about file extension etc., but how to create the mime type for my custom file?

The question: Do I need to be a content provider? I just want to import files (from backup) not provide anything. I've seen people having handlers for "application/abc" saying it's working fine, but how to add that connection for my file "myFile.abc" and the mime type?

Some direction how to register/map custom mime types would be appreciated! :)

Answer 1

As far as I can tell, mime types are pretty flexible (I created mine as application/whatever) and they're accepted immediately by Android, as far back as Dalvik version 2.1. To handle them properly, I added this intent-filter:

<intent-filter>
  <action android:name="android.intent.action.VIEW"/>
  <category android:name="android.intent.category.DEFAULT"/>
  <data android:mimeType="application/whatever" />
</intent-filter>

There is a caveat though. Even though I always set the type of the send Intent with intent.setType("application/whatever");, on some phones I've seen the actual data on arrival as application/octet (to see the value, I assigned the incoming Intent and inspected its value directly Intent currentIntent = getIntent();). The receiving Android device didn't know what to do with the incoming data and told me so. So I added

<intent-filter>
  <action android:name="android.intent.action.VIEW"/>
  <category android:name="android.intent.category.DEFAULT"/>
  <data android:mimeType="application/octet-stream" />
</intent-filter>

This approach could be troublesome of course, but the problem with Gmail at least is that it doesn't necessarily write the file with the name as it comes in, which renders any Path I choose to define useless. And at least with an incoming octet-stream you know it's not any app's specific data you're stealing away... Still, you should validate the data afterwards and not just assume it's valid for your app.