generate checksums without ivy

project/Checksums.scala

@@ -0,0 +1,34 @@
+import java.security.MessageDigest;
+import scala.annotation._
+import sbt._
+import sbt.Using._
+
+object Checksums {
+  private val bufferSize = 2048
+
+  def generate(source:File, target:File, algorithm:String):Unit =
+      IO write (target, compute(source, algorithm))
+
+  def compute(file:File, algorithm:String):String =
+      hex(raw(file, algorithm))
+
+  def raw(file:File, algorithm:String):Array[Byte]    =
+      (Using fileInputStream file) { is =>
+        val md  = MessageDigest getInstance algorithm
+        val buf = new Array[Byte](bufferSize)
+        md.reset()
+        @tailrec
+        def loop() {
+          val len = is read buf
+          if (len != -1) {
+            md update (buf, 0, len)
+            loop()
+          }
+        }
+        loop()
+        md.digest()
+      }
+
+  def hex(bytes:Array[Byte]):String =
+      bytes map { it => "%02x" format (it.toInt & 0xff) } mkString ""
+}