How do I close an enumerated file?
Let's say in action I have:
val linesEnu = {
val is = new java.io.FileInputStream(path)
val isr = new java.io.InputStreamReader(is, "UTF-8")
val br = new java.io.BufferedReader(isr)
import scala.collection.JavaConversions._
val rows: scala.collection.Iterator[String] = br.lines.iterator
Enumerator.enumerate(rows)
}
Ok.feed(linesEnu).as(HTML)
How do I close readers / streams?
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There is a callback onDoneEnumerating
that works like finally
(will always be called if it fails Enumerator
). You can close streams there.
val linesEnu = {
val is = new java.io.FileInputStream(path)
val isr = new java.io.InputStreamReader(is, "UTF-8")
val br = new java.io.BufferedReader(isr)
import scala.collection.JavaConversions._
val rows: scala.collection.Iterator[String] = br.lines.iterator
Enumerator.enumerate(rows).onDoneEnumerating {
is.close()
// ... Anything else you want to execute when the Enumerator finishes.
}
}
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The I / O tools provided Enumerator
give you this kind of resource management out of the box. if you create an enumerator with fromStream
, the stream is guaranteed to be closed upon startup (even if you are only reading one line, etc.).
So, for example, you could write the following:
import play.api.libs.iteratee._
val splitByNl = Enumeratee.grouped(
Traversable.splitOnceAt[Array[Byte], Byte](_ != '\n'.toByte) &>>
Iteratee.consume()
) compose Enumeratee.map(new String(_, "UTF-8"))
def fileLines(path: String): Enumerator[String] =
Enumerator.fromStream(new java.io.FileInputStream(path)).through(splitByNl)
It's a shame that the library doesn't provide linesFromStream
out of the box, but I personally would rather use fromStream
with manual splitting, etc., using an iterator and providing my own resource control.
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