Add DigestInputStream utils

core/src/main/scala/better/files/File.scala

@@ -5,7 +5,7 @@ import java.net.{URI, URL}
 import java.nio.charset.Charset
 import java.nio.channels._
 import java.nio.file._
-import attribute._
+import java.nio.file.attribute._
 import java.security.{DigestInputStream, MessageDigest}
 import java.time.Instant
 import java.util.zip._
@@ -319,6 +319,12 @@ class File private(val path: Path) {
   def inputStream(implicit openOptions: File.OpenOptions = File.OpenOptions.default): ManagedResource[InputStream] =
     newInputStream(openOptions).autoClosed
 
+  def newDigestInputStream(digest: MessageDigest)(implicit openOptions: File.OpenOptions = File.OpenOptions.default): DigestInputStream =
+    new DigestInputStream(newInputStream(openOptions), digest)
+
+  def digestInputStream(digest: MessageDigest)(implicit openOptions: File.OpenOptions = File.OpenOptions.default): ManagedResource[DigestInputStream] =
+    newDigestInputStream(digest)(openOptions).autoClosed
+
   def newScanner(implicit config: Scanner.Config = Scanner.Config.default): Scanner =
     Scanner(newBufferedReader(config.charset))(config)
 
@@ -360,21 +366,13 @@ class File private(val path: Path) {
     this
   }
 
-  def digest(algorithmName: String): Array[Byte] = {
-    val algorithm = MessageDigest.getInstance(algorithmName)
+  def digest(algorithm: MessageDigest): Array[Byte] = {
     listRelativePaths.toSeq.sorted foreach { relativePath =>
       val file: File = path.resolve(relativePath)
-
       if(file.isDirectory) {
         algorithm.update(relativePath.toString.getBytes)
       } else {
-        val buffer = new Array[Byte](8192)
-        val inputStream = new DigestInputStream(file.newInputStream, algorithm)
-        try {
-          while (inputStream.read(buffer) != -1) {}
-        } finally {
-          inputStream.close()
-        }
+        file.digestInputStream(algorithm).foreach(_.consume())
       }
     }
     algorithm.digest()
@@ -396,7 +394,7 @@ class File private(val path: Path) {
   /**
     * @return checksum of this file (or directory) in hex format
     */
-  def checksum(algorithm: String): String =
+  def checksum(algorithm: MessageDigest): String =
     DatatypeConverter.printHexBinary(digest(algorithm))
 
   def md5: String =

core/src/main/scala/better/files/Implicits.scala

@@ -1,13 +1,15 @@
 package better.files
 
-import java.io.{File => JFile, _}, StreamTokenizer.{TT_EOF => eof}
+import java.io.{File => JFile, _}
+import StreamTokenizer.{TT_EOF => eof}
 import java.nio.MappedByteBuffer
 import java.nio.channels.FileChannel
 import java.nio.charset.Charset
 import java.nio.file.Path
+import java.security.{DigestInputStream, MessageDigest}
 import java.util.StringTokenizer
 import java.util.stream.{Stream => JStream}
-import java.util.zip.{Deflater, GZIPInputStream, ZipEntry, ZipOutputStream, GZIPOutputStream}
+import java.util.zip.{Deflater, GZIPInputStream, GZIPOutputStream, ZipEntry, ZipOutputStream}
 
 import scala.annotation.tailrec
 import scala.util.control.NonFatal
@@ -38,6 +40,13 @@ trait Implicits {
       File(file.getPath)
   }
 
+  implicit class DigestInputStreamsOps(in: DigestInputStream) {
+    def consume(bufferSize: Int = 1<<10): Unit = {
+      val buffer = Array.ofDim[Byte](bufferSize)
+      while(in.read(buffer) != -1) {}
+    }
+  }
+
   implicit class InputStreamOps(in: InputStream) {
     def >(out: OutputStream): Unit =
       pipeTo(out)
@@ -262,6 +271,9 @@ trait Implicits {
     }
   }
 
+  implicit def stringToMessageDigest(algorithmName: String): MessageDigest =
+    MessageDigest.getInstance(algorithmName)
+
   implicit def tokenizerToIterator(s: StringTokenizer): Iterator[String] =
     produce(s.nextToken()).till(s.hasMoreTokens)
 

core/src/test/scala/better/files/FileSpec.scala

@@ -1,7 +1,5 @@
 package better.files
 
-import java.nio.charset.StandardCharsets
-
 import File.{root, home}
 import Dsl._
 
@@ -296,7 +294,6 @@ class FileSpec extends FlatSpec with BeforeAndAfterEach with Matchers {
   }
 
   it should "support hashing algos" in {
-    implicit val charset = StandardCharsets.UTF_8
     t1.writeText("")
     assert(md5(t1) == "D41D8CD98F00B204E9800998ECF8427E")
     assert(sha1(t1) == "DA39A3EE5E6B4B0D3255BFEF95601890AFD80709")
@@ -305,7 +302,6 @@ class FileSpec extends FlatSpec with BeforeAndAfterEach with Matchers {
   }
 
   it should "compute correct checksum for non-zero length string" in {
-    implicit val charset = StandardCharsets.UTF_8
     t1.writeText("test")
     assert(md5(t1) == "098F6BCD4621D373CADE4E832627B4F6")
     assert(sha1(t1) == "A94A8FE5CCB19BA61C4C0873D391E987982FBBD3")