I/O utils for Java serialization

CHANGES.md

@@ -14,6 +14,7 @@
 * [File.nonEmpty](https://github.com/pathikrit/better-files/commit/18c9cd51b7b2e503ff4944050ac5119470869e6e)
 * [Update metadata API](https://github.com/pathikrit/better-files/commit/c3d65951d80f09b813e158a9e3a1785c622353b3)
 * [Issue #80](https://github.com/pathikrit/better-files/issues/80): Unzip filters
+* [PR #107](https://github.com/pathikrit/better-files/pull/127): Java serialization utils
 
 ## v2.17.1
 

README.md

@@ -17,16 +17,17 @@
   0. [Simple I/O](#file-readwrite)  
   0. [Streams](#streams)
   0. [Encodings](#encodings)
+  0. [Java serialization utils](#java-serialization-utils)
   0. [Java compatibility](#java-interoperability)
   0. [Globbing](#globbing)
-  0. [File system operations](#file-system-operations)
+  0. [File system operations](#file-system-operations) 
   0. [Temporary files](#temporary-files)
   0. [UNIX DSL](#unix-dsl)
   0. [File attributes](#file-attributes)
   0. [File comparison](#file-comparison)
   0. [Zip/Unzip](#zip-apis)
   0. [Automatic Resource Management](#lightweight-arm)
-  0. [Scanner] (#scanner)
+  0. [Scanner](#scanner)
   0. [File Monitoring](#file-monitoring)
   0. [Reactive File Watcher](#akka-file-watcher)
 
@@ -207,6 +208,27 @@ If you also wish to write BOMs while encoding, you would need to supply it as:
 ```scala
 file.write("hello world")(charset = UnicodeCharset("UTF-8", writeByteOrderMarkers = true)) 
 ```
+
+### Java serialization utils
+
+Some common utils to serialize/deserialize using Java's serialization util
+```scala
+case class Person(name: String, age: Int)
+val person = new Person("Chris", 24)
+
+// Write
+file.newOutputStream.buffered.asObjectOutputStream.serialize(obj).flush()
+
+// Read
+val person2 = file.newInputStream.buffered.asObjectInputStream.readObject().asInstanceOf[Person]
+assert(person == person2)
+```
+
+The above can be simply written as:
+```scala
+val person2: Person = file.writeSerialized(person).readDeserialized[Person]
+assert(person == person2)
+```
 
 ### Java interoperability
 You can always access the Java I/O classes:

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

@@ -320,6 +320,7 @@ class File private(val path: Path) {
   def inputStream(implicit openOptions: File.OpenOptions = File.OpenOptions.default): ManagedResource[InputStream] =
     newInputStream(openOptions).autoClosed
 
+  //TODO: Move this to inputstream implicit
   def newDigestInputStream(digest: MessageDigest)(implicit openOptions: File.OpenOptions = File.OpenOptions.default): DigestInputStream =
     new DigestInputStream(newInputStream(openOptions), digest)
 
@@ -362,6 +363,25 @@ class File private(val path: Path) {
   def watchService: ManagedResource[WatchService] =
     newWatchService.autoClosed
 
+  /**
+    * Serialize a object using Java's serializer into this file
+    *
+    * @param obj
+    * @return
+    */
+  def writeSerialized(obj: Serializable)(implicit openOptions: File.OpenOptions = File.OpenOptions.default): this.type = {
+    createIfNotExists().outputStream(openOptions).foreach(_.buffered.asObjectOutputStream.serialize(obj).flush())
+    this
+  }
+
+  /**
+    * Deserialize a object using Java's default serialization from this file
+    *
+    * @return
+    */
+  def readDeserialized[A](implicit openOptions: File.OpenOptions = File.OpenOptions.default): A =
+    inputStream(openOptions).map(_.buffered.asObjectInputStream.readObject().asInstanceOf[A]).head
+
   def register(service: WatchService, events: File.Events = File.Events.all): this.type = {
     path.register(service, events.toArray)
     this

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

@@ -63,9 +63,15 @@ trait Implicits {
     def buffered: BufferedInputStream =
       new BufferedInputStream(in)
 
+    def buffered(bufferSize: Int): BufferedInputStream =
+      new BufferedInputStream(in, bufferSize)
+
     def gzipped: GZIPInputStream =
       new GZIPInputStream(in)
 
+    def asObjectInputStream: ObjectInputStream =
+      new ObjectInputStream(in)
+
     def reader(implicit charset: Charset = File.defaultCharset): InputStreamReader =
       new InputStreamReader(in, charset)
 
@@ -97,6 +103,9 @@ trait Implicits {
 
     def tee(out2: OutputStream): OutputStream =
       new TeeOutputStream(out, out2)
+
+    def asObjectOutputStream: ObjectOutputStream =
+      new ObjectOutputStream(out)
   }
 
   implicit class ReaderOps(reader: Reader) {
@@ -130,6 +139,18 @@ trait Implicits {
       file.collectChildren(child => matcher.matches(child.path))(visitOptions)
   }
 
+  implicit class ObjectInputStreamOps(ois: ObjectInputStream) {
+    def deserialize[A]: A =
+      ois.readObject().asInstanceOf[A]
+  }
+
+  implicit class ObjectOutputStreamOps(val oos: ObjectOutputStream) {
+    def serialize(obj: Serializable): oos.type = {
+      oos.writeObject(obj)
+      oos
+    }
+  }
+
   implicit class ZipOutputStreamOps(val out: ZipOutputStream) {
 
     /**

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

@@ -21,7 +21,7 @@ package object files extends Implicits {
 
   def resourceAsStream(name: String): InputStream = currentClassLoader().getResourceAsStream(name)
 
-  type ManagedResource[A <: Closeable] = Traversable[A]
+  type ManagedResource[A <: Closeable] = Traversable[A]   //TODO: Make this a class so we don't have to call .head
 
   // Some utils:
   private[files] def newMultiMap[A, B]: mutable.MultiMap[A, B] = new mutable.HashMap[A, mutable.Set[B]] with mutable.MultiMap[A, B]

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

@@ -446,4 +446,18 @@ class FileSpec extends CommonSpec {
 
     (t2 writeBytes t1.bytes).contentAsString shouldEqual t1.contentAsString
   }
+
+  it should "serialize/deserialize" in {
+    class Person(val name: String, val age: Int) extends Serializable
+    val p1 = new Person("Chris", 34)
+
+    File.usingTemporaryFile() {f => //serialization round-trip test
+      assert(f.isEmpty)
+      f.writeSerialized(p1)
+      assert(f.nonEmpty)
+      val p2: Person = f.readDeserialized[Person]
+      assert(p1.name === p2.name)
+      assert(p1.age === p2.age)
+    }
+  }
 }