SAF (Storage Access Framework) in Pyjnius for Android 10 and Higher

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What will you learn?

In this tutorial, you will master the usage of Storage Access Framework in Pyjnius for devices operating on Android 10 and above. By understanding how to implement SAF, you can efficiently access external files while complying with scoped storage restrictions.

Introduction to the Problem and Solution

When developing Android applications using Python that require access to external storage on devices running Android 10 and higher, scoped storage limitations often pose challenges. To overcome these constraints, the Storage Access Framework (SAF) offered by Pyjnius comes to the rescue. By integrating SAF into your Python codebase through Pyjnius, you can securely access files without relying on direct file paths.

By leveraging SAF, developers can ensure adherence to scoped storage requirements while effectively accessing external files on newer Android versions.

Code

# Import necessary modules from pyjnius
from jnius import autoclass

# Define the activity package name using pyjnius autoclass function
PythonActivity = autoclass('org.kivy.android.PythonActivity')
activity = PythonActivity.mActivity

# Launch SAF file picker dialog to get user-selected file URI using Intent.ACTION_OPEN_DOCUMENT
Intent = autoclass('android.content.Intent')
intent = Intent()
intent.setAction(Intent.ACTION_OPEN_DOCUMENT)
intent.addCategory(Intent.CATEGORY_OPENABLE)
intent.setType("*/*")

result = activity.startActivityForResult(intent, 0)

if result['resultCode'] == -1: # RESULT_OK value
    selected_file_uri = result['data'].getData().toString()

print(f"Selected File URI: {selected_file_uri}")

# Copyright PHD

Explanation

The provided code snippet demonstrates how Pyjnius can be utilized in Python to integrate the Storage Access Framework (SAF) for accessing files on Android 10 and higher devices: – Import essential classes from pyjnius, such as autoclass, facilitating interaction with Java classes. – Define the current activity context using PythonActivity.mActivity. – Create an Intent object with action ACTION_OPEN_DOCUMENT to trigger the SAF file picker dialog. – Upon user selection of a file via this dialog and successful confirmation (RESULT_OK), retrieve the file’s URI. – Display the selected file’s URI after retrieval.

    How does SAF differ from traditional file access methods?

    SAF employs content URIs instead of direct paths, ensuring secure shared file access across apps.

    Can I write data back using SAF?

    Yes, once permission is granted through SAF, writing data back securely is possible.

    Does utilizing SAF impact app performance?

    Using SAF may introduce slight overhead due to additional security checks compared to direct path access.

    Is it possible to select multiple files at once with SAF?

    Yes, users can select multiple files simultaneously by implementing intents correctly.

    Are there any specific permissions required for using SAF?

    Ensure your app has READ_EXTERNAL_STORAGE or WRITE_EXTERNAL_STORAGE permissions along with MANAGE_EXTERNAL_STORAGE permission if writing data back is necessary.

    Can I filter which types of files users can select through the dialog?

    Yes, by specifying MIME types during intent creation (setType), you can restrict selectable files based on type (e.g., images only with image/*).

    Conclusion

    In conclusion, combining Pyjnius with Storage Access Framework facilitates seamless integration of secure external file access functionality within Python applications targeting Android 10 and higher versions. Mastering this approach not only ensures compatibility but also aligns with modern security standards mandated by Google concerning scoped storage implementations.

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