FileProvider

Sharing a file

In this example you'll learn how to share a file with other apps. We'll use a pdf file in this example although the code works with every other format as well.

The roadmap:

Specify the directories in which the files you want to share are placed

To share files we'll use a FileProvider, a class allowing secure file sharing between apps. A FileProvider can only share files in predefined directories, so let's define these.

  1. Create a new XML file that will contain the paths, e.g. res/xml/filepaths.xml

  2. Add the paths

    <paths xmlns:android="http://schemas.android.com/apk/res/android">
        <files-path name="pdf_folder" path="documents/"/>
    </paths>
    

Define a FileProvider and link it with the file paths

This is done in the manifest:
<manifest>
    ...
    <application>
        ...
        <provider
            android:name="android.support.v4.context.FileProvider"
            android:authorities="com.mydomain.fileprovider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/filepaths" />
        </provider>
        ...
    </application>
    ...
</manifest>

Generate the URI for the file

To share the file we must provide an identifier for the file. This is done by using a URI (Uniform Resource Identifier).
// We assume the file we want to load is in the documents/ subdirectory
// of the internal storage
File documentsPath = new File(Context.getFilesDir(), "documents");
File file = new File(documentsPath, "sample.pdf");
// This can also in one line of course:
// File file = new File(Context.getFilesDir(), "documents/sample.pdf");

Uri uri = FileProvider.getUriForFile(getContext(), "com.mydomain.fileprovider", file);

As you can see in the code we first make a new File class representing the file. To get a URI we ask FileProvider to get us one. The second argument is important: it passes the authority of a FileProvider. It must be equal to the authority of the FileProvider defined in the manifest.

Share the file with other apps

We use ShareCompat to share the file with other apps:
Intent intent = ShareCompat.IntentBuilder.from(getContext())
    .setType("application/pdf")
    .setStream(uri)
    .setChooserTitle("Choose bar")
    .createChooserIntent()
    .addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);

Context.startActivity(intent);

A chooser is a menu from which the user can choose with which app he/she wants to share the file. The flag Intent.FLAG_GRANT_READ_URI_PERMISSION is needed to grant temporary read access permission to the URI.

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