samoa-api/src/main/java/org/apache/samoa/moa/core/InputStreamProgressMonitor.java

/*
 * 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.apache.samoa.moa.core;

import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.Serializable;

/**
 * Class for monitoring the progress of reading an input stream.
 * 
 * @author Richard Kirkby (rkirkby@cs.waikato.ac.nz)
 * @version $Revision: 7 $
 */
public class InputStreamProgressMonitor extends FilterInputStream implements Serializable {

  /** The number of bytes to read in total */
  protected int inputByteSize;

  /** The number of bytes read so far */
  protected int inputBytesRead;

  public InputStreamProgressMonitor(InputStream in) {
    super(in);
    try {
      this.inputByteSize = in.available();
    } catch (IOException ioe) {
      this.inputByteSize = 0;
    }
    this.inputBytesRead = 0;
  }

  public int getBytesRead() {
    return this.inputBytesRead;
  }

  public int getBytesRemaining() {
    return this.inputByteSize - this.inputBytesRead;
  }

  public double getProgressFraction() {
    return ((double) this.inputBytesRead / (double) this.inputByteSize);
  }

  /*
   * (non-Javadoc)
   * 
   * @see java.io.InputStream#read()
   */
  @Override
  public int read() throws IOException {
    int c = this.in.read();
    if (c > 0) {
      this.inputBytesRead++;
    }
    return c;
  }

  /*
   * (non-Javadoc)
   * 
   * @see java.io.InputStream#read(byte[])
   */
  @Override
  public int read(byte[] b) throws IOException {
    int numread = this.in.read(b);
    if (numread > 0) {
      this.inputBytesRead += numread;
    }
    return numread;
  }

  /*
   * (non-Javadoc)
   * 
   * @see java.io.InputStream#read(byte[], int, int)
   */
  @Override
  public int read(byte[] b, int off, int len) throws IOException {
    int numread = this.in.read(b, off, len);
    if (numread > 0) {
      this.inputBytesRead += numread;
    }
    return numread;
  }

  /*
   * (non-Javadoc)
   * 
   * @see java.io.InputStream#skip(long)
   */
  @Override
  public long skip(long n) throws IOException {
    long numskip = this.in.skip(n);
    if (numskip > 0) {
      this.inputBytesRead += numskip;
    }
    return numskip;
  }

  /*
   * (non-Javadoc)
   * 
   * @see java.io.FilterInputStream#reset()
   */
  @Override
  public synchronized void reset() throws IOException {
    this.in.reset();
    this.inputBytesRead = this.inputByteSize - this.in.available();
  }

}