How do I use the new Lollipop SD Card Access API on KITKAT devices?

Kit-Kat problem cannot write to external SD card,

As indicated in the Goolge Document To simplify the code on devices that are running KITKAT or earlier, you can use fromFile (File), which emulates the behavior DocumentProvider code below (New API) works for Lollipop, but how to use the new API to kitkat?

Also have a look at Kit-Kat Problem (new API)

public class MyActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_my);
    Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);
    startActivityForResult(intent, 42);
}

public void onActivityResult(int requestCode, int resultCode, Intent resultData) {
    if (resultCode == RESULT_OK) {
        Uri treeUri = resultData.getData();
        DocumentFile pickedDir = DocumentFile.fromFile(new File("/mnt/extSdCard/Test"));

        // List all existing files inside picked directory
        for (DocumentFile file : pickedDir.listFiles()) {
            Log.d("Tag", "Found file " + file.getName() + " with size " + file.length());
        }

        // Create a new file and write into it
        DocumentFile newFile = pickedDir.createFile("text/plain", "My Novel");
        OutputStream out = null;
        try {
            out = getContentResolver().openOutputStream(newFile.getUri());
            out.write("A long time ago...".getBytes());
            out.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.my, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}
}

      

How do I use fromFile?

I tried but it said Failed to create file: java.io.IOException: open failed: EACCES (Permission denied)

Even after adding use-permission android: name = "android.permission.WRITE_EXTERNAL_STORAGE"

Android version 4.4.2

 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_my);

    DocumentFile pickedDir = DocumentFile.fromFile(new File("/mnt/extSdCard/Test"));

    // List all existing files inside picked directory
    for (DocumentFile file : pickedDir.listFiles()) {
        Log.d("Tag", "Found file " + file.getName() + " with size " + file.length());
    }

    // Create a new file and write into it
    DocumentFile newFile = pickedDir.createFile("text/plain", "My Novel");
    OutputStream out = null;
    try {

        //Says NullPointerException
        out = getContentResolver().openOutputStream(newFile.getUri());                             out.write("A long time ago...".getBytes());
        out.close();
    } catch (Exception e) {
        e.printStackTrace();
    }        
}

      

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1 answer


The new API only helps people at Lollipop write to a secondary SD card, the people at KitKat are still out of luck .

DocumentFile.fromFile (...)

This does not give you any additional access to the main files beyond what your application already has.



To use new permissions created by Intent.ACTION_OPEN_DOCUMENT_TREE you must use the Uri returned by DocumentFile.fromTreeUri

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