Lift Framework example source code file (IoHelpers.scala)

This example Lift Framework source code file (IoHelpers.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Lift Framework tags/keywords

array, array, box, empty, empty, file, full, inputstream, io, iohelpers, iohelpers, string, string, t, thread

The Lift Framework IoHelpers.scala source code

/*
 * Copyright 2006-2011 WorldWide Conferencing, LLC
 *
 * 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 net.liftweb
package util

import java.io._
import scala.collection.mutable.ListBuffer
import ControlHelpers._
import common._

object IoHelpers extends IoHelpers

trait IoHelpers {
  /**
   * Execute the specified OS command and return the output of that command
   * in a Full Box if the command succeeds, or a Failure if an error occurs.
   */
  def exec(cmds: String*): Box[String] = {
    try {
      class ReadItAll(in: InputStream, done: String => Unit) extends Runnable {
        def run {
          val br = new BufferedReader(new InputStreamReader(in)) // default to platform character set
          val lines = new ListBuffer[String]
          var line = ""
          while (line != null) {
            line = br.readLine
            if (line != null) lines += line
          }
          br.close
          in.close
          done(lines.mkString("\n"))
        }
      }

      var stdOut = ""
      var stdErr = ""
      val proc = Runtime.getRuntime.exec(cmds.toArray)
      val t1 = new Thread(new ReadItAll(proc.getInputStream, x => stdOut = x))
      t1.start
      val t2 = new Thread(new ReadItAll(proc.getErrorStream, x => stdErr = x))
      val res = proc.waitFor
      t1.join
      t2.join
      if (res == 0) Full(stdOut)
      else Failure(stdErr, Empty, Empty)
    } catch {
      case e => Failure(e.getMessage, Full(e), Empty)
    }
  }

  /**
   * Read all data to the end of the specified Reader and concatenate
   * the resulting data into a string.
   */
  def readWholeThing(in: Reader): String = {
    val bos = new StringBuilder
    val ba = new Array[Char](4096)

    def readOnce {
      val len = in.read(ba)
      if (len < 0) return
      if (len > 0) bos.appendAll(ba, 0, len)
      readOnce
    }

    readOnce

    bos.toString
  }

  /**
   * Read an entire file into an Array[Byte]
   */
  def readWholeFile(file: File): Array[Byte] = readWholeStream(new FileInputStream(file))

  /**
   * Read all data from a stream into an Array[Byte]
   */
  def readWholeStream(in: InputStream): Array[Byte] = {
    val bos = new ByteArrayOutputStream
    val ba = new Array[Byte](4096)

    def readOnce {
      val len = in.read(ba)
      if (len > 0) bos.write(ba, 0, len)
      if (len >= 0) readOnce
    }

    readOnce

    in.close

    bos.toByteArray
  }

  /**
   * Executes by-name function f and then closes the Cloaseables parameters
   */
  def doClose[T](is: java.io.Closeable*)(f : => T): T = {
    try {
      f
    } finally {
      is.foreach(stream => tryo{ stream.close })
    }
  }
}