Is there a nice, safe, quick way to write an InputStream to a File in Scala?

Question

Specifically, I'm saving a file upload to local file in a Lift web app.

Answer 1

With Java 7 or later you can use Files from the new File I/O:

Files.copy(from, to) 

where from and to can be Paths or InputStreams. This way, you can even use it to conveniently extract resources from applications packed in a jar.

Answer 2

If it's a text file, and you want to limit yourself to Scala and Java, then using scala.io.Source to do the reading is probably the fastest--it's not built in, but easy to write:

def inputToFile(is: java.io.InputStream, f: java.io.File) {   val in = scala.io.Source.fromInputStream(is)   val out = new java.io.PrintWriter(f)   try { in.getLines().foreach(out.println(_)) }   finally { out.close } } 

But if you need other libraries anyway, you can make your life even easier by using them (as Michel illustrates).

(P.S.--in Scala 2.7, getLines should not have a () after it.)

(P.P.S.--in old versions of Scala, getLines did not remove the newline, so you need to print instead of println.)