SimpleStorage

Table of Contents

• Overview
  • Java Compatibility
• Terminology
• Check Accessible Paths
• Read Files
  • DocumentFileCompat
    • Example
  • MediaStoreCompat
    • Example
• Manage Files
  • DocumentFile
  • MediaFile
• Request Storage Access, Pick Folder & Files, Request Create File, etc.
• Move & Copy: Files & Folders
• Search: Files & Folders
• Compress & Unzip: Files & Folders
  • Compression
  • Decompression
• FAQ
• Other SimpleStorage Usage Examples
• License

Overview

The more higher API level, the more Google restricted file access on Android storage. Although Storage Access Framework (SAF) is designed to secure user's storage from malicious apps, but this makes us even more difficult in accessing files as a developer. Let's take an example where java.io.File has been deprecated in Android 10.

Simple Storage ease you in accessing and managing files across API levels. If you want to know more about the background of this library, please read this article: Easy Storage Access Framework in Android with SimpleStorage

Adding Simple Storage into your project is pretty simple:

implementation "com.anggrayudi:storage:X.Y.Z"

Where X.Y.Z is the library version:

All versions can be found here. To use SNAPSHOT version, you need to add this URL to the root Gradle:

allprojects {
    repositories {
        google()
        mavenCentral()
        // add this line
        maven { url "https://oss.sonatype.org/content/repositories/snapshots" }
    }
}

Java Compatibility

Simple Storage is built in Kotlin. Follow this documentation to use it in your Java project.

Note that some long-running functions like copy, move, search, compress, and unzip are now only available in Kotlin. They are powered by Kotlin Coroutines & Flow, which are easy to use. You can still use these Java features in your project, but you will need v1.5.6 which is the latest version that supports Java.

Terminology

Other Terminology

• Storage Permission – related to runtime permissions
• Storage Access – related to URI permissions

Check Accessible Paths

To check whether you have access to particular paths, call DocumentFileCompat.getAccessibleAbsolutePaths(). The results will look like this in breakpoint:

All paths in those locations are accessible via functions DocumentFileCompat.from*(), otherwise your action will be denied by the system if you want to access paths other than those, then functions DocumentFileCompat.from*() (next section) will return null as well. On API 28-, you can obtain it by requesting the runtime permission. For API 29+, it is obtained automatically by calling SimpleStorageHelper#requestStorageAccess() or SimpleStorageHelper#openFolderPicker(). The granted paths are persisted by this library via ContentResolver#takePersistableUriPermission(), so you don't need to remember them in preferences:

buttonSelectFolder.setOnClickListener {
    storageHelper.openFolderPicker()
}

storageHelper.onFolderSelected = { requestCode, folder ->
    // tell user the selected path
}

In the future, if you want to write files into the granted path, use DocumentFileCompat.fromFullPath():

val grantedPaths = DocumentFileCompat.getAccessibleAbsolutePaths(this)
val path = grantedPaths.values.firstOrNull()?.firstOrNull() ?: return
val folder = DocumentFileCompat.fromFullPath(this, path, requiresWriteAccess = true)
val file = folder?.makeFile(this, "notes", "text/plain")

Read Files

In Simple Storage, DocumentFile is used to access files when your app has been granted full storage access, included URI permissions for read and write. Whereas MediaFile is used to access media files from MediaStore without URI permissions to the storage.

You can read file with helper functions in DocumentFileCompat and MediaStoreCompat:

DocumentFileCompat

• DocumentFileCompat.fromFullPath()
• DocumentFileCompat.fromSimplePath()
• DocumentFileCompat.fromFile()
• DocumentFileCompat.fromPublicFolder()

Example

val fileFromExternalStorage = DocumentFileCompat.fromSimplePath(context, basePath = "Download/MyMovie.mp4")

val fileFromSdCard = DocumentFileCompat.fromSimplePath(context, storageId = "9016-4EF8", basePath = "Download/MyMovie.mp4")

MediaStoreCompat

• MediaStoreCompat.fromMediaId()
• MediaStoreCompat.fromFileName()
• MediaStoreCompat.fromRelativePath()
• MediaStoreCompat.fromFileNameContains()
• MediaStoreCompat.fromMimeType()
• MediaStoreCompat.fromMediaType()

Example

val myVideo = MediaStoreCompat.fromFileName(context, MediaType.DOWNLOADS, "MyMovie.mp4")

val imageList = MediaStoreCompat.fromMediaType(context, MediaType.IMAGE)

Manage Files

DocumentFile

Since java.io.File has been deprecated in Android 10, thus you have to use DocumentFile for file management.

Simple Storage adds Kotlin extension functions to DocumentFile, so you can manage files like this:

• DocumentFile.getStorageId()
• DocumentFile.getStorageType()
• DocumentFile.getBasePath()
• DocumentFile.copyFileTo()
• List<DocumentFile>.moveTo()
• DocumentFile.search()
• DocumentFile.deleteRecursively()
• DocumentFile.getProperties()
• DocumentFile.openOutputStream(), and many more…

MediaFile

For media files, you can have similar capabilities to DocumentFile, i.e.:

• MediaFile.absolutePath
• MediaFile.isPending
• MediaFile.delete()
• MediaFile.renameTo()
• MediaFile.copyFileTo()
• MediaFile.moveFileTo()
• MediaFile.openInputStream()
• MediaFile.openOutputStream(), etc.

Request Storage Access, Pick Folder & Files, Request Create File, etc.

Although user has granted read and write permissions during runtime, your app may still does not have full access to the storage, thus you cannot search, move and copy files. You can check whether you have the storage access via SimpleStorage.hasStorageAccess() or DocumentFileCompat.getAccessibleAbsolutePaths().

To enable full storage access, you need to open SAF and let user grant URI permissions for read and write access. This library provides you an helper class named SimpleStorageHelper to ease the request process:

class MainActivity : AppCompatActivity() {

    private val storageHelper = SimpleStorageHelper(this)

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // Only setup required callbacks, based on your need:
        storageHelper.onStorageAccessGranted = { requestCode, root ->
            // do stuff
        }
        storageHelper.onFolderSelected = { requestCode, folder ->
            // do stuff
        }
        storageHelper.onFileSelected = { requestCode, files ->
            // do stuff
        }
        storageHelper.onFileCreated = { requestCode, file ->
            // do stuff
        }

        // Depends on your actions:
        btnRequestStorageAccess.setOnClickListener { storageHelper.requestStorageAccess() }
        btnOpenFolderPicker.setOnClickListener { storageHelper.openFolderPicker() }
        btnOpenFilePicker.setOnClickListener { storageHelper.openFilePicker() }
        btnCreateFile.setOnClickListener { storageHelper.createFile("text/plain", "Test create file") }
    }

    override fun onSaveInstanceState(outState: Bundle) {
        storageHelper.onSaveInstanceState(outState)
        super.onSaveInstanceState(outState)
    }

    override fun onRestoreInstanceState(savedInstanceState: Bundle) {
        super.onRestoreInstanceState(savedInstanceState)
        storageHelper.onRestoreInstanceState(savedInstanceState)
    }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        // Mandatory for direct subclasses of android.app.Activity,
        // but not for subclasses of androidx.fragment.app.Fragment, androidx.activity.ComponentActivity, androidx.appcompat.app.AppCompatActivity
        storageHelper.storage.onActivityResult(requestCode, resultCode, data)
    }

    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<String>, grantResults: IntArray) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        // Mandatory for direct subclasses of android.app.Activity,
        // but not for subclasses of androidx.fragment.app.Fragment, androidx.activity.ComponentActivity, androidx.appcompat.app.AppCompatActivity
        storageHelper.onRequestPermissionsResult(requestCode, permissions, grantResults)
    }
}

Simple, right?

This helper class contains default styles for managing storage access. If you want to use custom dialogs for SimpleStorageHelper, just copy the logic from this class.

Move & Copy: Files & Folders

Simple Storage helps you in copying/moving files & folders via:

• DocumentFile.copyFileTo()
• DocumentFile.moveFileTo()
• DocumentFile.copyFolderTo()
• DocumentFile.moveFolderTo()

For example, you can move a folder with few lines of code:

val folder: DocumentFile = ...
val targetFolder: DocumentFile = ...

val job = ioScope.launch {
  folder.moveFolderTo(applicationContext, targetFolder, skipEmptyFiles = false, updateInterval = 1000, onConflict = object : FolderConflictCallback(uiScope) {
    override fun onParentConflict(destinationFolder: DocumentFile, action: ParentFolderConflictAction, canMerge: Boolean) {
      handleParentFolderConflict(destinationFolder, action, canMerge)
    }

    override fun onContentConflict(
      destinationFolder: DocumentFile,
      conflictedFiles: MutableList<FileConflict>,
      action: FolderContentConflictAction
    ) {
      handleFolderContentConflict(action, conflictedFiles)
    }
  }).onCompletion {
    if (it is CancellationException) {
      Timber.d("Folder move is aborted")
    }
  }.collect { result ->
    when (result) {
      is FolderResult.Validating -> Timber.d("Validating...")
      is FolderResult.Preparing -> Timber.d("Preparing...")
      is FolderResult.CountingFiles -> Timber.d("Counting files...")
      is FolderResult.DeletingConflictedFiles -> Timber.d("Deleting conflicted files...")
      is FolderResult.Starting -> Timber.d("Starting...")
      is FolderResult.InProgress -> Timber.d("Progress: ${result.progress.toInt()}% | ${result.fileCount} files")
      is FolderResult.Completed -> uiScope.launch {
        Timber.d("Completed: ${result.totalCopiedFiles} of ${result.totalFilesToCopy} files")
        Toast.makeText(baseContext, "Moved ${result.totalCopiedFiles} of ${result.totalFilesToCopy} files", Toast.LENGTH_SHORT).show()
      }

      is FolderResult.Error -> uiScope.launch {
        Timber.e(result.errorCode.name)
        Toast.makeText(baseContext, "An error has occurred: ${result.errorCode.name}", Toast.LENGTH_SHORT).show()
      }
    }
  }
}

// call this function somewhere, for example in a dialog with a cancel button:
job.cancel() // it will abort the process

The coolest thing of this library is you can ask users to choose Merge, Replace, Create New, or Skip Duplicate folders & files whenever a conflict is found via onConflict(). Here're screenshots of the sample code when dealing with conflicts:

Read MainActivity from the sample code if you want to mimic above dialogs.

Search: Files & Folders

You can search files and folders by using DocumentFile.search() extension function:

ioScope.launch {
  val nameToFind = "nicko" // search files with name containing "nicko"
  folder.search(recursive = true, regex = Regex("^.*$nameToFind.*\$"), updateInterval = 1000).collect {
    // update results every 1 second
    Timber.d("Found ${it.size} files, last: ${it.lastOrNull()?.fullName}")
  }
}

Compress & Unzip: Files & Folders

Compression

To compress files and folders, use List<DocumentFile>.compressToZip() extension function:

ioScope.launch {
  // make sure you have an URI access to /storage/emulated/0/Documents, otherwise it will return null
  val targetZipFile = DocumentFileCompat.createFile(baseContext, basePath = "Documents/compress test.zip", mimeType = "application/zip")
  if (targetZipFile != null) {
    listOf(folder).compressToZip(baseContext, targetZipFile, deleteSourceWhenComplete = false, updateInterval = 500).collect {
      when (it) {
        is ZipCompressionResult.CountingFiles -> Timber.d("Calculating...")
        is ZipCompressionResult.Compressing -> Timber.d("Compressing... ${it.progress.toInt()}%")
        is ZipCompressionResult.Completed -> Timber.d("Completed: ${it.zipFile.fullName}")
        is ZipCompressionResult.Error -> Timber.e(it.errorCode.name)
        is ZipCompressionResult.DeletingEntryFiles -> Timber.d("Deleting ...") // will be emitted if `deleteSourceWhenComplete` is true
      }
    }
  }
}

If you don't have any URI access, then you can request the user to create a ZIP file in the desired location:

storageHelper.onFileCreated = { requestCode, file ->
  ioScope.launch {
    listOf(folder).compressToZip(baseContext, file).collect {
      // do stuff
    }
  }
}
storageHelper.createFile(mimeType = "application/zip", fileName = "compress test", initialPath = FileFullPath(baseContext, StorageId.PRIMARY, "Documents"))

Decompression

FYI, decompressing ZIP files is also easy:

ioScope.launch {
  file.decompressZip(baseContext, targetFolder)
    .onCompletion {
      if (it is CancellationException) {
        Timber.d("Decompression is aborted")
      }
    }.collect {
      when (it) {
        is ZipDecompressionResult.Validating -> Timber.d("Validating...")
        is ZipDecompressionResult.Decompressing -> Timber.d("Decompressing... ${it.bytesDecompressed}")
        is ZipDecompressionResult.Completed -> uiScope.launch {
          Toast.makeText(baseContext, "Decompressed successfully", Toast.LENGTH_SHORT).show()
        }

        is ZipDecompressionResult.Error -> uiScope.launch {
          Toast.makeText(baseContext, "An error has occurred: ${it.errorCode.name}", Toast.LENGTH_SHORT).show()
        }
      }
    }
}

FAQ

Having trouble? Read the Frequently Asked Questions or join the Discussions.

Other SimpleStorage Usage Examples

SimpleStorage is used in these open source projects. Check how these repositories use it:

• Snapdrop
• MaterialPreference
• Super Productivity
• Shared Storage for Flutter
• Nextcloud Cookbook
• Audiobookshelf

License

Copyright © 2020-2024 Anggrayudi Hardiannico A.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.