access assets from monodroid class library

问题

Is it possible to access files (with build action "AndroidAsset") from a monodroid class library in a monodroid application that references the class library ?

I have created an "Assets" folder in the class lib and added a text file with build action "AndroidAsset", but from the app I could not access it via Assets.Open("file.txt");

I was hoping that the Assets from the class lib and the main application could somehow be "merged"...

回答1:

No - you a can't access the assets from a class lib - only from the main exe project.

This is similar to the situation with Java Android projects.

One route around this might be to use embedded resources instead - see the answer to this question I asked on xamarin's forums - http://forums.xamarin.com/discussion/186/is-there-a-cross-platform-way-to-include-string-resources-from-class-library-projects - note that I haven't tried this yet

回答2:

Is it possible to access files (with build action "AndroidAsset") from a monodroid class library in a monodroid application that references the class library ?

Yes. Just access them "as normal" via Context.Assets.Open. There is only one source of assets in the application, so any component can access any and all assets, if they have access to an AssetManager instance.

However, that just takes what you're asking at face-value. Can a Library project use the Context.Assets property? Certainly, if you provide it a Context instance.

But can a Library project provide it's own assets for inclusion into the application? No.

I have created an "Assets" folder in the class lib and added a text file with build action "AndroidAsset", but from the app I could not access it via Assets.Open("file.txt");

Library projects cannot provide assets that will be included in the larger application. Java doesn't support this either, afaik.

回答3:

Things to remember

1 Build Action is AndroidAsset (Properties)

2 Copy to output directory Do not copy (Properties)

3 Add the file to the Assets folder

var destinationPath = Path.Combine(System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal), "yourfilename.txt");
            using (Stream source = Assets.Open("yourfilename.txt"))
            using (var dest = System.IO.File.Create (destinationPath)) {
                source.CopyTo (dest);
            }

Sometimes this will still fail, monodroid bug. The best thing to do is check to see if the files were included correctly.

Load up Eclipse, in the device browser, you should see your simulator.  
Go to the directory data/app/    download the file yourappname.apk
This is just a zip file, so change the extension to .zip and open the
zip archive. And goto the folder /assets and see if the file you are trying 
to load is in there.

Also if you try to grab a file off a physical device your testing on, some allow it and other don't. This is easiest to test on the simulator.

回答4:

It is possible to access the Assets files from a library:

var sourcePath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal);
//var files = Directory.GetFiles(sourcePath);
var filePath = Path.Combine(sourcePath, "MyAssetFile.bin");
var content = File.ReadAllBytes(filePath);

来源：https://stackoverflow.com/questions/13100666/access-assets-from-monodroid-class-library

标签

xamarin.android

assets