Write a large Inputstream to File in Kotlin - kotlin

Question

I have a large stream of text coming back from REST web service and I would like to write it directly to file. What is the simplest way of doing this?
I have written the following function extension that WORKS. But I can't help thinking that there is a cleaner way of doing this.
Note: I was hoping to use try with resources to auto close the stream and file
fun File.copyInputStreamToFile(inputStream: InputStream) {
val buffer = ByteArray(1024)
inputStream.use { input ->
this.outputStream().use { fileOut ->
while (true) {
val length = input.read(buffer)
if (length <= 0)
break
fileOut.write(buffer, 0, length)
}
fileOut.flush()
}
}
}

Answer 1

You can simplify your function by using the copyTo function:
fun File.copyInputStreamToFile(inputStream: InputStream) {
this.outputStream().use { fileOut ->
inputStream.copyTo(fileOut)
}
}

Answer 2

My proposition is:
fun InputStream.toFile(path: String) {
File(path).outputStream().use { this.copyTo(it) }
}
without closing current stream
InputStream.toFile("/path/filename")
also, do not forget to handle exceptions, for example if write permission is denied :)

Answer 3

I suggest to make like this:
fun InputStream.toFile(path: String) {
use { input ->
File(path).outputStream().use { input.copyTo(it) }
}
}
and then to use like:
InputStream.toFile("/some_path_to_file")

Answer 4

You needs to do like this
#Throws
fun copyDataBase() {
var myInput = context.getAssets().open(DB_NAME)
var outFileName = DB_PATH + DB_NAME
var fileOut: OutputStream = FileOutputStream(outFileName)
val buffer: ByteArray = ByteArray(1024)
var length: Int? = 0
while (true) {
length = myInput.read(buffer)
if (length <= 0)
break
fileOut.write(buffer, 0, length)
}
fileOut.flush()
fileOut.close()
myInput.close()
throw IOException()
}

Answer 5

What appears to have worked for me is this:
fun fileCopyer(localFileA: File, localFileB: File) {
var output = localFileA.inputStream()
output.copyTo(localFileB.outputStream())
output.close()
}