fm.common.ByteBufferInputStream.scala Maven / Gradle / Ivy

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/*
 * Copyright 2014 Frugal Mechanic (http://frugalmechanic.com)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package fm.common

import java.io.{InputStream, IOException, SequenceInputStream}
import java.nio.{ByteBuffer, InvalidMarkException}
import java.util.Collections

object ByteBufferInputStream {
  /**
   * This takes combined multiple ByteBuffers into a single InputStream by
   * wrapping them in ByteBufferInputStreams and then using a
   * java.io.SequenceInputStream to combine them.
   * 
   * NOTE: This calls duplicate() on the ByteBuffer to prevent modifying the original
   */
  def apply(bufs: Seq[ByteBuffer]): InputStream = {
    if (bufs.size == 1) new ByteBufferInputStream(bufs.head.duplicate())
    else new SequenceInputStream(bufs.map{ (buf: ByteBuffer) => new ByteBufferInputStream(buf.duplicate()) }.asJavaEnumeration())
  }
}

/**
 * A Simple InputStream wrapper around a ByteBuffer
 */
final class ByteBufferInputStream(buf: ByteBuffer) extends InputStream {
  override def markSupported(): Boolean = true
  
  override def mark(readlimit: Int): Unit = buf.mark()
  
  override def reset(): Unit = try {
    buf.reset()
  } catch {
    // InputStream specifies that we throw an IOException "if the stream has
    // not been marked or if the mark has been invalidated"
    case ex: InvalidMarkException => throw new IOException(ex)
  }
  
  def read(): Int = {
    if (!buf.hasRemaining()) return -1
    buf.get() & 0xFF
  }
  
  override def read(bytes: Array[Byte], off: Int, len: Int): Int = {
    if (!buf.hasRemaining()) return -1
    
    val lenToRead = math.min(len, buf.remaining())
    buf.get(bytes, off, lenToRead)
    lenToRead
  }
}