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@takezoe
Created November 17, 2011 06:21
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wraps java.io.InputStream by scala.collection.immutable.Stream
val stream = fromInputStream(new java.io.FileInputStream("test.jpg"), 8 * 1024)
/**
* Makes Stream which reads every bytes with specified size from java.io.InputStream.
*/
@tailrec
def fromInputStream(in: java.io.InputStream, bufferSize: Int): Stream[Array[Byte]] = {
val buffer = new Array[Byte](bufferSize)
in.read(buffer) match {
case -1 => Stream.empty
case len => buffer.slice(0, len) #:: fromInputStream(in, bufferSize)
}
}
@xuwei-k
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xuwei-k commented Nov 17, 2011

これ

def fromInputStream(s:java.io.InputStream) = 
  Iterator.continually(s.read).takeWhile(-1 !=).map{_.toByte} // 場合によっては Stream.continually ?

より、ある一定サイズの Array[Byte] に読み込んだほうが効率いいんですかね?

InputStream の内部実装によるかな・・・

@takezoe
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takezoe commented Nov 17, 2011

直接FileInputStreamとか読むならある程度のサイズをまとめて読んだほうが圧倒的に速いです。
BufferedInputStreamかましたときは…どうなんでしょう。

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