record some scala code

Download.scala

// a simple script
// batch download from http://www.andrew.cmu.edu/course/15-749/READINGS/optional/

//extract file name
def getAllFiles(url:String):List[String] = {
    import scala.io._
    val regex = """<a href="(.+?\.pdf)">""".r
    val content = Source.fromURL(url).mkString
    regex.findAllMatchIn(content).map(_.group(1)).toList
}

// do download
def download(list:List[String],url:String) = {
    import java.nio.channels._
    import java.nio._
    import java.net._
    list foreach { name =>
        val website = new URL(s"$url$name")
        val rbc = Channels.newChannel(website.openStream())
        //current directory
        val fos = new java.io.FileOutputStream(s"$name")
        fos.getChannel().transferFrom(rbc,0,Long.MaxValue)
        fos.close()
    }
}

// or use
def download2(list:List[String],url:String) = {
    import java.nio.file._
    import scala.io._
    list foreach { name =>
        //use ISO-8859-1 codec to download binary
        val content = Source.fromURL(s"$url$name","ISO-8859-1")
        Files.write(Paths.get(s"$name"),content.map(_.toByte).toArray)
    }
}
//run
downloadu(getAllFiles("http://www.andrew.cmu.edu/course/15-749/READINGS/optional/"),"http://www.andrew.cmu.edu/course/15-749/READINGS/optional/")