Develop Reference

Store File To External Storage Not Working For Android 10 and above - Android Studio/Kotlin

My app has an extract button that takes the data from text view and paste it in a text file "Ledger.txt". It creates a folder in Mobile internal Storage Root Directory "WaterLedger" and place a Ledger.txt file in it and if the text file is already present it appends the text in the file. The code is only working till android 9 not above.
In Android 10 on pressing Extract button it asks "grant permission to write file in storage" but even if you press Yes it still wont create folder (WaterLerger) and paste/update data in Text File (Ledger.txt)
Here is the code
class WriteFile: AsyncTask<String, Int, String>() {
private val mFolder = "/WaterLedger"
lateinit var folder: File
internal var writeThis = "string to cacheApp.txt"
internal var cacheApptxt = "Ledger.txt"
override fun doInBackground(vararg writethis: String): String? {
val received = writethis[0]
if(received.isNotEmpty()){
writeThis = received
}
folder = File(Environment.getExternalStorageDirectory(),"$mFolder/")
if(!folder.exists() || folder.exists()){
folder.mkdir()
val readME = File(folder, cacheApptxt)
val file = File(readME.path)
val out: BufferedWriter
try {
out = BufferedWriter(FileWriter(file, true), 1024)
out.write("****Ledger Updated On Dated:$currentDate*****\n")
out.newLine()
out.write(writeThis)
out.newLine()
out.close()
Log.d("Output_Success", folder.path)
} catch (e: Exception) {
Log.d("Output_Exception", "$e")
}
}
return folder.path
}
// Driver Code
extract.setOnClickListener {
var pathToFileCreated = ""
val anRW = ReadandWrite().readAndwriteStorage(this, this)
if (anRW) {
pathToFileCreated = WriteFile().execute("$StringBuilder").get()
Log.d("pathToFileCreated", pathToFileCreated)
Toast.makeText(this,"File Saved",android.widget.Toast.LENGTH_LONG).show()
}

This will give you External Pictures directory URI (You can create your desirable directory into it):
private fun createTextURI(): Uri? {
val imageCollection = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q)
MediaStore.Video.Media.getContentUri(MediaStore.VOLUME_EXTERNAL_PRIMARY)
else
MediaStore.Video.Media.EXTERNAL_CONTENT_URI
val fileName = System.currentTimeMillis()
val contentValues = ContentValues().apply {
put(MediaStore.MediaColumns.DISPLAY_NAME, "$fileName.txt")
put(MediaStore.MediaColumns.MIME_TYPE, "text/plain")
}
val finalURI = contentResolver.insert(imageCollection, contentValues)
resultUri = finalURI
return finalURI
}
Use this URI for file creation like this:
new File(finalURI.getPath());
And write into this file which you created above. ✌
Make sure you have WRITE_EXTERNAL_STORAGE permission.
Ref. Demo App

Create Zip file where the contents are a bitmaps for Android Kotlin

I am currently writing an app where I need to create a zip file that has a bunch of bitmap images in it. I have a List that has the Uri's for all the images.
Could someone please direct me to how I can create a new zip file and then add all the images to a newly created zip file?

Assuming you have external storage permissions granted following should work
val BUFFER = 1024
fun Context.zip(files: Array<Uri>, zipFileName: String?) {
try {
var origin: BufferedInputStream? = null
val dest = FileOutputStream(zipFileName)
val out = ZipOutputStream(BufferedOutputStream(dest))
val data = ByteArray(BUFFER)
for (uri in files) {
val stringUri = uri.toString()
val fi = openFileInput(stringUri)
origin = BufferedInputStream(fi, BUFFER)
val entry = ZipEntry(stringUri.substring(stringUri.lastIndexOf("/") + 1))
out.putNextEntry(entry)
var count: Int
while (origin.read(data, 0, BUFFER).also { count = it } != -1) {
out.write(data, 0, count)
}
origin.close()
}
out.close()
} catch (e: Exception) {
e.printStackTrace()
}
}
Remember this is an extension function on Context so it will require to be called with a context like context.zip(listOfUris, "ZIP_FILE_NAME_HERE")

How to get path /storage/emulated/0/Download/file_name.mime_type for Android 10 and above

I am saving a file inside the Downloads directory of the device (Android 11) to be viewed later by my app. I'm allowing multiple file types like pdf, word etc. I was able to save the file like this: (I got this code sample from here)
#TargetApi(29)
private suspend fun downloadQ(
url: String,
filename: String,
mimeType: String
) =
withContext(Dispatchers.IO) {
val response = ok.newCall(Request.Builder().url(url).build()).execute()
if (response.isSuccessful) {
val values = ContentValues().apply {
put(MediaStore.Downloads.DISPLAY_NAME, filename)
put(MediaStore.Downloads.MIME_TYPE, mimeType)
put(MediaStore.Downloads.IS_PENDING, 1)
}
val resolver = context.contentResolver
val uri =
resolver.insert(MediaStore.Downloads.EXTERNAL_CONTENT_URI, values)
uri?.let {
resolver.openOutputStream(uri)?.use { outputStream ->
val sink = outputStream.sink().buffer()
response.body()?.source()?.let { sink.writeAll(it) }
sink.close()
}
values.clear()
values.put(MediaStore.Downloads.IS_PENDING, 0)
resolver.update(uri, values, null, null)
} ?: throw RuntimeException("MediaStore failed for some reason")
} else {
throw RuntimeException("OkHttp failed for some reason")
}
}
But when I tried to retrieve the file, I tried with the following ways that did not work:
val idColumn = cursor.getColumnIndexOrThrow(MediaStore.Downloads._ID)
val id = cursor.getLong(idColumn)
Log.d("uri id ","$id")
val contentUri = ContentUris.withAppendedId(MediaStore.Downloads.EXTERNAL_CONTENT_URI,id)
This approach threw an exception:
java.lang.IllegalArgumentException: Failed to find configured root that contains /external/downloads/78
I got this ID (here 78) from the query and cursor from ContentResolver.query() and I hoped it to return the Uri from which I could get the File.
The second approach was this:
val uri = MediaStore.Downloads.getContentUri("external",id)
uri.path?.let { filePath ->
Log.d("uri path ",filePath)
val file = File(filePath)
} ?: Log.d("uri path ","null")
I used external as the directory based on this answer, but this approach also threw the same exception
java.lang.IllegalArgumentException: Failed to find configured root that contains /external/downloads/78
At the end what ended up working was hardcoding something like this after I used a file explorer app to view the exact directory path:
val file = File("storage/emulated/0/Download/$name.$extension")
So my question is, how do I get the value of this path dynamically, and is this path the same for all devices that can be used like this way?
EDIT: I also wanted to know if I am using the filename and it's extension to view the file, then if user downloads another file with same name then how do I make sure that correct file is opened? (even if i make a separate directory for my app inside Download, user could still download the same file twice that has a name like storage/emulated/0/Download/myDir/file(2).extension )

Try with the following code it will help you.
private fun readFile(){
val FILENAME = "user_details.txt"
val dir = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
File(
Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)
.toString() + "/" + "folderName"
)
} else {
File(
Environment.getExternalStorageDirectory()
.toString() + "/${Environment.DIRECTORY_DOWNLOADS}/" + "folderName"
)
}
dir.apply {
if(this.exists()) File(this, FILENAME).apply {
FileInputStream(this).apply {
val stringBuffer = StringBuffer()
var i: Int
while (this.read().also { i = it } != -1) {
stringBuffer.append(i.toChar())
}
close()
}
}
}
}

You can use
{Environment.DIRECTORY_DOWNLOADS} + "/folderName/file_name.mime_type"

/storage/emulated/0/Download/12d82c65-00a5-4c0a-85bc-238c28005c33.bin

Saving file in internal storage using Uri (obtained from Storage Access network)

I'm using Storage Access Network to pick file and save in internal storage so that app can use if in future.
I'm getting URI without any issues. It's something like content://com.android.providers.media.documents/document/image%3A141274
Problem comes when I'm trying to save image into internal directory. Code passes without crashes, image with same size is saved into internal directory (I can see it in device Explorer: https://take.ms/3TwBS).
But image itself is broken and can't be opened.
Here's code I'm using (after getting URI)
val destinationFile = File("${context.filesDir.absolutePath}/$fileName")
try {
val writer = FileWriter(destinationFile)
writer.append(readTextFromUri(it))
writer.flush()
writer.close()
} catch (e: Exception) {
e.printStackTrace()
}
#Throws(IOException::class)
private fun readTextFromUri(uri: Uri): String {
val inputStream = activity!!.contentResolver.openInputStream(uri)
val reader = BufferedReader(InputStreamReader(inputStream))
val stringBuilder = StringBuilder()
var line: String? = null
while ({ line = reader.readLine(); line }() != null) {
stringBuilder.append(line)
}
inputStream?.close()
reader.close()
return stringBuilder.toString()
}

As #CommonsWare described I should have used proper dealing with files, not texts.
Proper way to do:
private fun inputStreamToFile(uri: Uri){
val inputStream = contentResolver.openInputStream(uri)
val output = FileOutputStream(File("${filesDir.absoluteFile}/magic.png"))
inputStream?.copyTo(output, 4 * 1024)
}
Or longer way (without extension functions)
fun inputStreamToFile(uri: Uri){
val inputStream = contentResolver.openInputStream(uri)
inputStream.use {
val directory = getDir("test", Context.MODE_PRIVATE)
val file = File(directory, "correct.txt")
val output = FileOutputStream(file)
output.use {
val buffer = ByteArray(4 * 1024) // or other buffer size
var read: Int = inputStream?.read(buffer) ?: -1
while (read != -1) {
output.write(buffer, 0, read)
read = inputStream?.read(buffer) ?: -1
}
output.flush()
}
}
}

Android: Read a file without external storage permission

I don't want my app to require any permissions, but I want the user to be able to select a file for reading. My app doesn't need arbitrary access to the filesystem. However, all openfiledialog implementations I have researched so far seem to assume permission to access external storage.
One workaround I can think of is to configure my app to be among the list of apps to open a certain type of file. I haven't tried this, but I hope this would work without permission to access external storage. However, user guidance would be less then ideal in this case. I would prefer a solution with a dialog and have the user pick the file.
I think this requirement does not undermine security, because the user has full control over the file my app can read. Is this possible somehow?

However, all openfiledialog implementations I have researched so far seem to assume permission to access external storage.
Set your minSdkVersion to 19, then use ACTION_OPEN_DOCUMENT, part of the Storage Access Framework.
Or, if you need your minSdKVersion to be below 19, use ACTION_GET_CONTENT on the older devices.
You will get a Uri back via onActivityResult(). Use a ContentResolver and methods like openInputStream() to consume the content identified by that Uri.
I haven't tried this, but I hope this would work without permission to access external storage
Only if you exclude file: Uri values. For example, an <intent-filter> that supports only content: Uri values would work.

Android 11 Resolve file access issue without use of MANAGE_EXTERNAL_STORAGE.
I have added code for get doc file and Upload to server.
AndroidManifest
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<application
android:preserveLegacyExternalStorage="true"
android:requestLegacyExternalStorage="true"
</application>
Now, Add this lib in your project
https://github.com/FivesoftCode/FilePicker
Add below code to Activity/Fragment
FilePicker.from(activity)
.setFileTypes(FilePicker.IMAGE, FilePicker.VIDEO) //Set file types you want to pick.
.setAllowMultipleFiles(true) //Allow user to select multiple files
.setListener { files -> //Wait for results
if (files != null && files.size > 0) {
//Do something with uris.
for (items in files) {
val extension: String = getMimeType(activity!!,items)!!
if (extension == "pdf") {
val cacheDir: String = context!!.cacheDir.toString()
val getCopyFilePath = copyFileToInternalStorage(context!!,items,cacheDir)
Log.e("TAG", "getPathToUploadDoc: " + getCopyFilePath )
}
}
} else {
//Add msg here...
}
}
.setTitle("Pick a file from My Files")
.pick() //Open file picker
Add below method for get Mime Type
fun getMimeType(context: Context, uri: Uri): String? {
val extension: String?
//Check uri format to avoid null
extension = if (uri.scheme == ContentResolver.SCHEME_CONTENT) {
//If scheme is a content
val mime = MimeTypeMap.getSingleton()
mime.getExtensionFromMimeType(context.contentResolver.getType(uri))
} else {
//If scheme is a File
//This will replace white spaces with %20 and also other special characters. This will avoid returning null values on file name with spaces and special characters.
MimeTypeMap.getFileExtensionFromUrl(Uri.fromFile(File(uri.path)).toString())
}
return extension
}
fun getFiledetails(uri: Uri,context: Context,getCopyFilePath:String): NormalFile? {
// var result: String? = null
if (uri.scheme == "content") {
val cursor: Cursor = context.contentResolver.query(uri,
FileLoader.FILE_PROJECTION, null, null, null)!!
try {
if (cursor != null && cursor.moveToFirst()) {
// result = cursor.getString(cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME))
val path: String = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.MediaColumns.DATA))
if (path != null && path != "") {
//Create a File instance
cursor.getLong(cursor.getColumnIndexOrThrow(BaseColumns._ID))
// cursor.getLong(cursor.getColumnIndexOrThrow(BaseColumns._ID)).toInt()
cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.MediaColumns.TITLE))
// cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.MediaColumns.DATA))
cursor.getLong(cursor.getColumnIndexOrThrow(MediaStore.MediaColumns.SIZE))
cursor.getLong(cursor.getColumnIndexOrThrow(MediaStore.MediaColumns.DATE_ADDED))
cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Files.FileColumns.MIME_TYPE))
}
}
} finally {
cursor.close()
}
}
/*if (result == null) {
result = uri.path
val cut = result!!.lastIndexOf('/')
if (cut != -1) {
result = result.substring(cut + 1)
}
}*/
return file
}
fun copyFileToInternalStorage(context: Context?,uri: Uri, newDirName: String): String? {
val returnCursor = context!!.contentResolver.query(
uri, arrayOf(
OpenableColumns.DISPLAY_NAME, OpenableColumns.SIZE
), null, null, null
)
/*
* Get the column indexes of the data in the Cursor,
* * move to the first row in the Cursor, get the data,
* * and display it.
* */
val nameIndex = returnCursor!!.getColumnIndex(OpenableColumns.DISPLAY_NAME)
val sizeIndex = returnCursor.getColumnIndex(OpenableColumns.SIZE)
returnCursor.moveToFirst()
val name = returnCursor.getString(nameIndex)
val size = java.lang.Long.toString(returnCursor.getLong(sizeIndex))
val output: File
output = if (newDirName != "") {
val dir = File(/*context!!.filesDir.toString() + "/" +*/ newDirName)
if (!dir.exists()) {
dir.mkdir()
}
File(/*context!!.filesDir.toString() + "/" +*/ newDirName + "/" + name)
} else {
File(context!!.filesDir.toString() + "/" + name)
}
try {
val inputStream: InputStream? = context!!.contentResolver.openInputStream(uri)
val outputStream = FileOutputStream(output)
var read = 0
val bufferSize = 1024
val buffers = ByteArray(bufferSize)
while (inputStream?.read(buffers).also { read = it!! } != -1) {
outputStream.write(buffers, 0, read)
}
inputStream?.close()
outputStream.close()
} catch (e: Exception) {
Log.e("Exception", e.message!!)
}
return output.path
}
For upload Doc
implementation 'net.gotev:uploadservice:2.1'
var uploadId = UUID.randomUUID().toString()
val url = ServerConfig.MAIN_URL
uploadReceiver.setDelegate(this)
uploadReceiver.setUploadID(uploadId)
val data = MultipartUploadRequest(mContext, uploadId, url)
.addFileToUpload(path, "attachment")
.addHeader("Authentication", getMD5EncryptedString())
.addParameter(USER_ID,1)
.setMaxRetries(5)
.startUpload()
fun getMD5EncryptedString(): String {
val encTarget = ServerConfig.AUTHENTICATE_VALUE //Any pwd
var mdEnc: MessageDigest? = null
try {
mdEnc = MessageDigest.getInstance("MD5")
} catch (e: NoSuchAlgorithmException) {
println("Exception while encrypting to md5")
e.printStackTrace()
}
mdEnc!!.update(encTarget.toByteArray(), 0, encTarget.length)
var md5 = BigInteger(1, mdEnc.digest()).toString(16)
while (md5.length < 32) {
md5 = "0$md5"
}
return md5
}