java.io.IOException: Cannot make changes to file

Question

I am using JAudioTagger library for reading and writing tags for an audio file. I am able to read the tags but unable to write them.

I am retrieving audio file path like this :

 private String getSongPath(long songId) {
        String path = null;
        ContentResolver contentResolver = getContentResolver();
        Uri uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
        String[] projection = {MediaStore.Audio.Media.DATA};
        String selection = MediaStore.Audio.Media._ID + " == ?";
        String[] selectionArgs = {String.valueOf(songId)};

        Cursor cursor = contentResolver.query(uri, projection, selection, selectionArgs, null);

        if (cursor != null) {
            int pathCol = cursor.getColumnIndexOrThrow(projection[0]);
            cursor.moveToFirst();
            path = cursor.getString(pathCol);
            cursor.close();
        }

        return path;
    }

Then to write tags using JAudioTagger :

File songFile = new File(path); // path looks like /storage/3932-3434/Music/xyz.mp3
AudioFile audiofile = = AudioFileIO.read(songFile);
Tag tag = = audiofile.getTag();
tag.setField(FieldKey.TITLE, title);
// some more setField calls for different feilds
audiofile.commit();

The commit() method is giving following Exception :

org.jaudiotagger.audio.exceptions.CannotWriteException: java.io.IOException: Cannot make changes to file xyz.mp3 at org.jaudiotagger.audio.mp3.MP3File.commit(MP3File.java:799) at com.techapps.musicplayerplus.MainActivity$17.onClick(MainActivity.java:2125) at android.support.v7.app.AlertController$ButtonHandler.handleMessage(AlertController.java:157) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) 06-18 10:59:48.134 8802-8802/com.techapps.musicplayerplus W/System.err:
at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) Caused by: java.io.IOException: Cannot make changes to file Saibo.mp3 at org.jaudiotagger.audio.mp3.MP3File.precheck(MP3File.java:824) at org.jaudiotagger.audio.mp3.MP3File.save(MP3File.java:850) at org.jaudiotagger.audio.mp3.MP3File.save(MP3File.java:783) at org.jaudiotagger.audio.mp3.MP3File.commit(MP3File.java:795)

I am running this code on Android 6 while my app is targeted at SDK 22. I have also mentioned following permission in manifest.

android.permission.WRITE_EXTERNAL_STORAGE

Still I am unable to write to SD card. Please help me. Thanks in advance.

Answer 1

You have to use Storage Access Framework (SAF) to access SD Card from API 19 (Kitkat) onward.

1. First we need to ask user to provide a URI of the folder we want to access. If we want access to entire SD card, user needs to provide URI of SD card's root folder. For example, when user hits Edit button, we have to first show hint dialog box, asking user to select required directory in SD Card which we want to access. You can display following image in hint dialog box to ask user to select root directory of SD Card :

2. When user dismisses hint dialog box, you need to trigger Storage Access Framework :

   private void triggerStorageAccessFramework() {
    Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);
    startActivityForResult(intent, REQUEST_CODE_STORAGE_ACCESS);
    }
   
   public final void onActivityResult(final int requestCode, final int resultCode, final Intent resultData) {
    if (resultCode == Activity.RESULT_OK) {
           if (requestCode == REQUEST_CODE_STORAGE_ACCESS) {
                   Uri treeUri = null;
                   // Get Uri from Storage Access Framework.
                   treeUri = resultData.getData();
                   pickedDir= DocumentFile.fromTreeUri(this, treeUri);
   
                   if (!isSDCardRootDirectoryUri(treeUri)) {
                       Toast.makeText(this, "Wrong directory selected. Please select SD Card root directory.", Toast.LENGTH_LONG).show();
                       createSDCardHintDialog().show();
                       return;
                   }        
   
                   // Persist URI in shared preference so that you can use it later.                   
                   SharedPreferences sharedPreferences = getSharedPreferences(App.PREFERENCE_FILENAME, Context.MODE_PRIVATE);
                   SharedPreferences.Editor editor = sharedPreferences.edit();
                   editor.putString(App.SDCARD_URI_KEY, treeUri.toString());
                   editor.apply();  
   
                   // Persist access permissions, so you dont have to ask again
                   final int takeFlags = resultData.getFlags() & (Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
                   getContentResolver().takePersistableUriPermission(treeUri, Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
   
               }
      } 
   
   private boolean isSDCardRootDirectoryUri(Uri treeUri) {
       String uriString = treeUri.toString();
       return uriString.endsWith("%3A");
   }
   

Once you get Uri of user picked directory, you can perform write operation using SAF : (creadit : this answer )

public void writeFile(DocumentFile pickedDir) {
    try {
        DocumentFile file = pickedDir.createFile("image/jpeg", "try2.jpg");
        OutputStream out = getContentResolver().openOutputStream(file.getUri());
        try {

            // write the image content

        } finally {
            out.close();
        }

    } catch (IOException e) {
        throw new RuntimeException("Something went wrong : " + e.getMessage(), e);
    }
}