Custom ContentProvider for Android to enable files stored in the internal storage to be opened by external apps

FileProvider.kt

import android.content.ContentProvider
import android.content.ContentValues
import android.database.Cursor
import android.net.Uri
import android.os.ParcelFileDescriptor
import java.io.File
import java.io.FileNotFoundException

/**
 * Created by thorstenhack on 28.11.17.
 * Declare in manifest: <provider android:name=".FileProvider" android:authorities="com.your.package" android:exported="true" />
 * Usage:
 *          val intent = Intent().setDataAndType(Uri.parse("content://com.your.package/${relativePathInFilesDir}", "mimetype")
 *          intent.flags = Intent.FLAG_GRANT_READ_URI_PERMISSION
 *          startActivity(intent)
 */
class FileProvider : ContentProvider() {

    override fun insert(uri: Uri?, values: ContentValues?): Uri? = null

    override fun query(uri: Uri?, projection: Array<out String>?, selection: String?, selectionArgs: Array<out String>?, sortOrder: String?): Cursor? = null

    override fun onCreate() = true

    override fun update(uri: Uri?, values: ContentValues?, selection: String?, selectionArgs: Array<out String>?) = 0

    override fun delete(uri: Uri?, selection: String?, selectionArgs: Array<out String>?) = 0

    override fun getType(uri: Uri?) = null

    @Throws(FileNotFoundException::class)
    override fun openFile(uri: Uri, mode: String): ParcelFileDescriptor? {
        val privateFile = File(context!!.filesDir, uri.path)
        return ParcelFileDescriptor.open(privateFile, ParcelFileDescriptor.MODE_READ_ONLY)
    }

}