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A lightweight library to execute external processes from Java.
There is a newer version: 1.12
/*
 * Copyright (C) 2014 ZeroTurnaround 
 * Contains fragments of code from Apache Commons Exec, rights owned
 * by Apache Software Foundation (ASF).
 *
 * 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.
 * 
 * NOTICE: This file originates from the Apache Commons Exec package.
 * It has been modified to fit our needs.
 * 
 * The following is the original header of the file in Apache Commons Exec:  
 * 
 *   Licensed to the Apache Software Foundation (ASF) under one or more
 *   contributor license agreements.  See the NOTICE file distributed with
 *   this work for additional information regarding copyright ownership.
 *   The ASF licenses this file to You 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 org.zeroturnaround.exec.stream;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Copies all data from an input stream to an output stream.
 */
public class StreamPumper implements Runnable {

  private static final Logger log = LoggerFactory.getLogger(StreamPumper.class);

  /** the default size of the internal buffer for copying the streams */
  private static final int DEFAULT_SIZE = 1024;

  /** the input stream to pump from */
  private final InputStream is;

  /** the output stream to pmp into */
  private final OutputStream os;

  /** the size of the internal buffer for copying the streams */ 
  private final int size;

  /** was the end of the stream reached */
  private boolean finished;

  /** close the output stream when exhausted */
  private final boolean closeWhenExhausted;

  /**
   * Create a new stream pumper.
   * 
   * @param is input stream to read data from
   * @param os output stream to write data to.
   * @param closeWhenExhausted if true, the output stream will be closed when the input is exhausted.
   */
  public StreamPumper(final InputStream is, final OutputStream os,
      final boolean closeWhenExhausted) {
    this.is = is;
    this.os = os;
    this.size = DEFAULT_SIZE;
    this.closeWhenExhausted = closeWhenExhausted;
  }

  /**
   * Create a new stream pumper.
   *
   * @param is input stream to read data from
   * @param os output stream to write data to.
   * @param closeWhenExhausted if true, the output stream will be closed when the input is exhausted.
   * @param size the size of the internal buffer for copying the streams
   */
  public StreamPumper(final InputStream is, final OutputStream os,
      final boolean closeWhenExhausted, final int size) {
    this.is = is;
    this.os = os;
    this.size = (size > 0 ? size : DEFAULT_SIZE);
    this.closeWhenExhausted = closeWhenExhausted;
  }

  /**
   * Create a new stream pumper.
   * 
   * @param is input stream to read data from
   * @param os output stream to write data to.
   */
  public StreamPumper(final InputStream is, final OutputStream os) {
    this(is, os, false);
  }

  /**
   * Copies data from the input stream to the output stream. Terminates as
   * soon as the input stream is closed or an error occurs.
   */
  public void run() {
    log.trace("{} started.", this);
    synchronized (this) {
      // Just in case this object is reused in the future
      finished = false;
    }

    final byte[] buf = new byte[this.size];

    int length;
    try {
      while ((length = is.read(buf)) > 0) {
        os.write(buf, 0, length);
      }
    } catch (Exception e) {
      // nothing to do - happens quite often with watchdog
    } finally {
      log.trace("{} finished.", this);
      if (closeWhenExhausted) {
        try {
          os.close();
        } catch (IOException e) {
          log.error("Got exception while closing exhausted output stream", e);
        }
      }
      synchronized (this) {
        finished = true;
        notifyAll();
      }
    }
  }

  /**
   * Tells whether the end of the stream has been reached.
   * 
   * @return true is the stream has been exhausted.
   */
  public synchronized boolean isFinished() {
    return finished;
  }

  /**
   * This method blocks until the stream pumper finishes.
   * 
   * @see #isFinished()
   */
  public synchronized void waitFor() throws InterruptedException {
    while (!isFinished()) {
      wait();
    }
  }
}