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I currently try to read a given inputStream as base64 encoded string in Kotlin. Sadly, it crashes the whole Android application with out of memory error as soon as the file is bigger than around 20 MegaBytes. I like to extend this for at least 40MB.
I think I need to read and convert the bytes of the stream in blocks like 8K for processing, but I can't find any Kotlin example about how to do this as I cannot simply convert the blocks to base64 and concatenate them. This does not work for base64 because of the encoding.
I think I need some sort of stream base64 encoder and I can't find any solution for this that works for me. The JAVA code I can find here in StackOverflow I'm not able to convert to Kotlin as I'm new to Kotlin and Java in general :-(
Also, I'm reading binary data and can't utilize any lineReader function I find every here and there. It should work on blocks with given byte size.
This is the function that currently crashes if the file is bigger than about 20MB:
private fun pushAttachmentToJS(uri: Uri) {
try {
val inputStream = contentResolver.openInputStream(uri)
inputStream.use { stream ->
// Next two lines need a replacement working in blocks
val fileBytes = stream?.readBytes()
val fB64 = Base64.encodeToString(fileBytes, Base64.NO_WRAP) // <-- CRASH
// (... further processing of the fB64 string)
}
} catch (e: IOException) {
e.printStackTrace()
}
}
Is someone having something that works in Kotlin?
EDIT: I had some partial success in the meantime. But still issues I have to verify...
private fun pushAttachmentToJS(uri: Uri) {
try {
val inputStream = contentResolver.openInputStream(uri)
inputStream.use { stream ->
val encoder = Base64.getEncoder().withoutPadding()
val buffer = ByteArray(12000) // bytes buffer (multiple of 3!)
val builder = StringBuilder()
var bytesRead: Int
var lastSize = 0
while (true) {
bytesRead = stream!!.read(buffer)
if (bytesRead == -1) break
lastSize = bytesRead // remember to later get the padding
val chunk = buffer.copyOfRange(0, bytesRead)
val encodedChunk = encoder.encodeToString(chunk)
// Append the encoded chunk to the StringBuilder
builder.append(encodedChunk)
}
// Add necessary padding to the final string
val remainder = lastSize % 4
if (remainder != 0) {
val paddingNeeded = 4 - remainder
repeat(paddingNeeded) {
builder.append('=')
}
}
val fB64 = builder.toString()
// (... further processing of the fB64 string)
}
} catch (e: IOException) {
e.printStackTrace()
}
}
But now the Base64 encoded string seems not okay. At least, it does not work as intended. Will need further inspection tomorrow...
EDIT: I found a solution. See answer post below.
I currently try to read a given inputStream as base64 encoded string in Kotlin. Sadly, it crashes the whole Android application with out of memory error as soon as the file is bigger than around 20 MegaBytes. I like to extend this for at least 40MB.
I think I need to read and convert the bytes of the stream in blocks like 8K for processing, but I can't find any Kotlin example about how to do this as I cannot simply convert the blocks to base64 and concatenate them. This does not work for base64 because of the encoding.
I think I need some sort of stream base64 encoder and I can't find any solution for this that works for me. The JAVA code I can find here in StackOverflow I'm not able to convert to Kotlin as I'm new to Kotlin and Java in general :-(
Also, I'm reading binary data and can't utilize any lineReader function I find every here and there. It should work on blocks with given byte size.
This is the function that currently crashes if the file is bigger than about 20MB:
private fun pushAttachmentToJS(uri: Uri) {
try {
val inputStream = contentResolver.openInputStream(uri)
inputStream.use { stream ->
// Next two lines need a replacement working in blocks
val fileBytes = stream?.readBytes()
val fB64 = Base64.encodeToString(fileBytes, Base64.NO_WRAP) // <-- CRASH
// (... further processing of the fB64 string)
}
} catch (e: IOException) {
e.printStackTrace()
}
}
Is someone having something that works in Kotlin?
EDIT: I had some partial success in the meantime. But still issues I have to verify...
private fun pushAttachmentToJS(uri: Uri) {
try {
val inputStream = contentResolver.openInputStream(uri)
inputStream.use { stream ->
val encoder = Base64.getEncoder().withoutPadding()
val buffer = ByteArray(12000) // bytes buffer (multiple of 3!)
val builder = StringBuilder()
var bytesRead: Int
var lastSize = 0
while (true) {
bytesRead = stream!!.read(buffer)
if (bytesRead == -1) break
lastSize = bytesRead // remember to later get the padding
val chunk = buffer.copyOfRange(0, bytesRead)
val encodedChunk = encoder.encodeToString(chunk)
// Append the encoded chunk to the StringBuilder
builder.append(encodedChunk)
}
// Add necessary padding to the final string
val remainder = lastSize % 4
if (remainder != 0) {
val paddingNeeded = 4 - remainder
repeat(paddingNeeded) {
builder.append('=')
}
}
val fB64 = builder.toString()
// (... further processing of the fB64 string)
}
} catch (e: IOException) {
e.printStackTrace()
}
}
But now the Base64 encoded string seems not okay. At least, it does not work as intended. Will need further inspection tomorrow...
EDIT: I found a solution. See answer post below.
Share Improve this question edited Nov 19, 2024 at 13:34 Volker asked Nov 18, 2024 at 11:43 VolkerVolker 5071 gold badge4 silver badges20 bronze badges 6 | Show 1 more comment1 Answer
Reset to default 0I finally solved it this way to save as much memory as possible:
Encode Uri to base64 string:
private fun convertUriToB64(uri: Uri) {
try {
val inputStream = contentResolver.openInputStream(uri)
inputStream?.use { stream ->
val filename = getFileNameFromUri(uri)
val encoder = Base64.getEncoder().withoutPadding()
val buffer = ByteArray(480000) // bytes buffer (multiple of 3!)
val builder = StringBuilder()
var bytesRead: Int
var sLength = 0
while (true) {
bytesRead = stream.read(buffer)
if (bytesRead == -1) break
val chunk = buffer.copyOfRange(0, bytesRead)
val encodedChunk = encoder.encodeToString(chunk)
builder.append(encodedChunk)
// count b64 string length to later get padding remainder
sLength += encodedChunk.length
}
// Add padding
val remainder = sLength % 4
if (remainder != 0) {
val paddingNeeded = 4 - remainder
repeat(paddingNeeded) {
builder.append('=')
}
}
// handle the result here:
return builder.toString()
}
} catch (e: IOException) {
e.printStackTrace()
}
}
Decode base64 string to file:
@OptIn(ExperimentalEncodingApi::class)
fun storeB64asFile(storageFilePath: File, base64binary: String): Boolean {
val step = 40000 // multiple of 4!
var pos = 0
val os = FileOutputStream(storageFilePath)
while (true) {
var end = pos + step
if (end > base64binary.length) {
end = base64binary.length
}
os.write(kotlin.io.encoding.Base64.decode(base64binary, pos, end))
pos += step
if (pos > base64binary.length) {
break;
}
}
os.flush()
os.close()
return true
}
This is stripped down. You might need to add additional error handling and input validation.
本文标签： androidKotlin Convert binary InputStream to base64 string in blocksbufferedStack Overflow
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contentResolver.openInputStream(uri)returnsnull, you typically don't want to run the block at all; so it's better then to useinputStream?.use { stream ->- this also makesstreamnon-nullable. – k314159 Commented Nov 18, 2024 at 14:29