How to download and save a file from the internet using Scala?
Here is a naive implementation by scala.io.Source.fromURL
and java.io.FileWriter
def downloadFile(token: String, fileToDownload: String) {
try {
val src = scala.io.Source.fromURL("http://randomwebsite.com/docs?t=" + token + "&p=tsr%2F" + fileToDownload)
val out = new java.io.FileWriter("src/test/resources/testingUpload1.txt")
out.write(src.mkString)
out.close
} catch {
case e: java.io.IOException => "error occured"
}
}
Your code works for me... There are other possibilities that make empty file.
Here is a safer alternative to new URL(url) #> new File(filename) !!
:
val url = new URL(urlOfFileToDownload)
val connection = url.openConnection().asInstanceOf[HttpURLConnection]
connection.setConnectTimeout(5000)
connection.setReadTimeout(5000)
connection.connect()
if (connection.getResponseCode >= 400)
println("error")
else
url #> new File(fileName) !!
Two things:
- When downloading from an
URL
object, if an error (404
for instance) is returned, then theURL
object will throw aFileNotFoundException
. And since this exception is generated from another thread (asURL
happens to run on a separate thread), a simpleTry
ortry/catch
won't be able to catch the exception. Thus the preliminary check for the response code:if (connection.getResponseCode >= 400)
. - As a consequence of checking the response code, the connection might sometimes get stuck opened indefinitely for improper pages (as explained here). This can be avoided by setting a timeout on the connection:
connection.setReadTimeout(5000)
.
I know this is an old question, but I just came across a really nice way of doing this :
import sys.process._
import java.net.URL
import java.io.File
def fileDownloader(url: String, filename: String) = {
new URL(url) #> new File(filename) !!
}
Hope this helps. Source.
You can now simply use fileDownloader function to download the files.
fileDownloader("http://ir.dcs.gla.ac.uk/resources/linguistic_utils/stop_words", "stop-words-en.txt")