如何获取 Android 10 及更高版本的路径 /storage/emulated/0/Download/file_name.mime_type

Question

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 )

Answer 1

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()
       }
   }
  }
}

Answer 2

You can use

{Environment.DIRECTORY_DOWNLOADS} + "/folderName/file_name.mime_type"

Answer 3

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