001/*
002 * Copyright (C) 2007 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
005 * in compliance with the License. You may obtain a copy of the License at
006 *
007 * http://www.apache.org/licenses/LICENSE-2.0
008 *
009 * Unless required by applicable law or agreed to in writing, software distributed under the License
010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
011 * or implied. See the License for the specific language governing permissions and limitations under
012 * the License.
013 */
014
015package com.google.common.io;
016
017import static com.google.common.base.Preconditions.checkNotNull;
018
019import com.google.common.annotations.GwtIncompatible;
020import java.io.FilterOutputStream;
021import java.io.IOException;
022import java.io.OutputStream;
023
024/**
025 * An OutputStream that counts the number of bytes written.
026 *
027 * @author Chris Nokleberg
028 * @since 1.0
029 */
030@GwtIncompatible
031public final class CountingOutputStream extends FilterOutputStream {
032
033  private long count;
034
035  /**
036   * Wraps another output stream, counting the number of bytes written.
037   *
038   * @param out the output stream to be wrapped
039   */
040  public CountingOutputStream(OutputStream out) {
041    super(checkNotNull(out));
042  }
043
044  /** Returns the number of bytes written. */
045  public long getCount() {
046    return count;
047  }
048
049  @Override
050  public void write(byte[] b, int off, int len) throws IOException {
051    out.write(b, off, len);
052    count += len;
053  }
054
055  @Override
056  public void write(int b) throws IOException {
057    out.write(b);
058    count++;
059  }
060
061  // Overriding close() because FilterOutputStream's close() method pre-JDK8 has bad behavior:
062  // it silently ignores any exception thrown by flush(). Instead, just close the delegate stream.
063  // It should flush itself if necessary.
064  @Override
065  public void close() throws IOException {
066    out.close();
067  }
068}