안드로이드 - SAF(Storage Access Framework)로 파일 읽고 쓰는 방법

val READ_REQUEST_CODE: Int = 42

val intent = Intent(Intent.ACTION_OPEN_DOCUMENT).apply {    // 1
    addCategory(Intent.CATEGORY_OPENABLE)   // 2
    type = "image/*"    // 3
}

startActivityForResult(intent, READ_REQUEST_CODE)   // 4

override fun onActivityResult(requestCode: Int, resultCode: Int, resultData: Intent?) {
    super.onActivityResult(requestCode, resultCode, resultData)

    if (requestCode == READ_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
        resultData?.data?.also { uri ->
            Log.i(TAG, "Uri: $uri")   // 1
            dumpImageMetaData(uri)    // 2
            showImage(uri)    // 3
        }
    }
}

fun dumpImageMetaData(uri: Uri) {
    val cursor: Cursor? = contentResolver.query( uri, null, null, null, null, null)
    cursor?.use {
        if (it.moveToFirst()) {
            val displayName: String =
                it.getString(it.getColumnIndex(OpenableColumns.DISPLAY_NAME))  // 1
            Log.i(TAG, "Display Name: $displayName")

            val sizeIndex: Int = it.getColumnIndex(OpenableColumns.SIZE)  // 2
            val size: String = if (!it.isNull(sizeIndex)) {
                it.getString(sizeIndex)
            } else {
                "Unknown"
            }
            Log.i(TAG, "Size: $size")
        }
    }
}

OpenExampleActivity: Uri: content://com.android.providers.media.documents/document/image%3A45
OpenExampleActivity: Display Name: matterhorn-4535693_1920.jpg
OpenExampleActivity: Size: 862778

private fun showImage(uri: Uri) {
    GlobalScope.launch {    // 1
        val bitmap = getBitmapFromUri(uri)    // 2
        withContext(Dispatchers.Main) {
            mainImageView.setImageBitmap(bitmap)    // 3
        }
    }
}

@Throws(IOException::class)
private fun getBitmapFromUri(uri: Uri): Bitmap {
    val parcelFileDescriptor: ParcelFileDescriptor? = contentResolver.openFileDescriptor(uri, "r")
    val fileDescriptor: FileDescriptor = parcelFileDescriptor!!.fileDescriptor
    val image: Bitmap = BitmapFactory.decodeFileDescriptor(fileDescriptor)
    parcelFileDescriptor.close()
    return image
}

Log.d(TAG, "Uri from onActivityResult: $uri")
val docFile = DocumentFile.fromTreeUri(this, uri)!!
Log.d(TAG, "Uri from DocumentFile: ${docFile.uri}")

Uri from onActivityResult: content://com.android.externalstorage.documents/tree/14E7-1B13%3AMovies
Uri from DocumentFile: content://com.android.externalstorage.documents/tree/14E7-1B13%3AMovies/document/14E7-1B13%3AMovies

val docUri = Uri.parse("content://com.android.externalstorage.documents/tree/14E7-1B13%3AMovies/document/14E7-1B13%3AMovies")

val intent = Intent(Intent.ACTION_OPEN_DOCUMENT_TREE)
intent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, docUri);
startActivityForResult(intent, REQUEST_OPEN_TREE)

Sets the desired initial location visible to user when file chooser is shown.

Applicable to Intent with actions:
  Intent#ACTION_OPEN_DOCUMENT
  Intent#ACTION_CREATE_DOCUMENT
  Intent#ACTION_OPEN_DOCUMENT_TREE

Location should specify a document URI or a tree URI with document ID. If this URI identifies a non-directory, document navigator will attempt to use the parent of the document as the initial location.

The initial location is system specific if this extra is missing or document navigator failed to locate the desired initial location.

val WRITE_REQUEST_CODE: Int = 43

val fileName = "NewImage.jpg"   // 1
val intent = Intent(Intent.ACTION_CREATE_DOCUMENT).apply {  // 2
    addCategory(Intent.CATEGORY_OPENABLE)   // 3
    type = "image/jpg"    // 4
    putExtra(Intent.EXTRA_TITLE, fileName)   // 5
}

startActivityForResult(intent, WRITE_REQUEST_CODE)    // 6

override fun onActivityResult(requestCode: Int, resultCode: Int, resultData: Intent?) {
    super.onActivityResult(requestCode, resultCode, resultData)

    if (requestCode == WRITE_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
        resultData?.data?.also { uri ->
            Log.i(TAG, "Uri: $uri")   // 1
            writeImage(uri)   // 2
        }
    }
}

private fun writeImage(uri: Uri) {
    GlobalScope.launch {
        contentResolver.openFileDescriptor(uri, "w").use {    // 1
            FileOutputStream(it!!.fileDescriptor).use { it ->   // 2
                writeFromRawDataToFile(it)    // 3
                it.close()
            }
        }
        withContext(Dispatchers.Main) {   //  4
            Toast.makeText(applicationContext, "Done writing an image", Toast.LENGTH_SHORT).show()
        }
    }
}

private fun writeFromRawDataToFile(outStream: FileOutputStream) {   
    val imageInputStream = resources.openRawResource(R.raw.my_image)  // 5
    while (true) {
        val data = imageInputStream.read()
        if (data == -1) {
            break
        }
        outStream.write(data)   // 6
    }
    imageInputStream.close()
}

val intent = Intent(Intent.ACTION_OPEN_DOCUMENT).apply {
    addCategory(Intent.CATEGORY_OPENABLE)
    type = "image/*"
}

startActivityForResult(intent, READ_REQUEST_CODE)

override fun onActivityResult(requestCode: Int, resultCode: Int, resultData: Intent?) {
    super.onActivityResult(requestCode, resultCode, resultData)

    if (requestCode == READ_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
        resultData?.data?.also { uri ->
            Log.i(TAG, "Uri: $uri")
            deleteFile(uri)   // 1
        }
    }
}

private fun deleteFile(uri: Uri) {
    DocumentsContract.deleteDocument(contentResolver, uri)    // 2
    Toast.makeText(applicationContext, "Done deleting an image", Toast.LENGTH_SHORT).show()
}

val takeFlags: Int = intent.flags and
        (Intent.FLAG_GRANT_READ_URI_PERMISSION or Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
// Check for the freshest data.
contentResolver.takePersistableUriPermission(uri, takeFlags)

private val REQUEST_OPEN_TREE = 44

val intent = Intent(Intent.ACTION_OPEN_DOCUMENT_TREE)   // 1
startActivityForResult(intent, REQUEST_OPEN_TREE)

override fun onActivityResult(requestCode: Int, resultCode: Int, resultData: Intent?) {
    super.onActivityResult(requestCode, resultCode, resultData)

    if (requestCode == REQUEST_OPEN_TREE && resultCode == Activity.RESULT_OK) {
        resultData?.data?.also { uri ->
            val takeFlags: Int = intent.flags and
                    (Intent.FLAG_GRANT_READ_URI_PERMISSION or Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
            contentResolver.takePersistableUriPermission(uri, takeFlags)  // 1
            printDirFiles(uri) // 2
        }
    }
}

private fun printDirFiles(uri: Uri) {
    val docFile = DocumentFile.fromTreeUri(this, uri)!!   // 3
    if (docFile.canRead()) {
        val files = docFile.listFiles()   // 4
        for (file : DocumentFile in files) {
            Log.d(TAG, "List files: ${file.name}")  // 5
        }
    }
}

TreeExampleActivity: List files: NewImage.jpg (1)
TreeExampleActivity: List files: NewImage.jpg