001/*
002 * Copyright (C) 2007 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package com.google.common.io;
018
019import com.google.common.annotations.Beta;
020
021import java.io.FilterInputStream;
022import java.io.IOException;
023import java.io.InputStream;
024
025/**
026 * An {@link InputStream} that counts the number of bytes read.
027 *
028 * @author Chris Nokleberg
029 * @since 1.0
030 */
031@Beta
032public final class CountingInputStream extends FilterInputStream {
033
034  private long count;
035  private long mark = -1;
036
037  /**
038   * Wraps another input stream, counting the number of bytes read.
039   *
040   * @param in the input stream to be wrapped
041   */
042  public CountingInputStream(InputStream in) {
043    super(in);
044  }
045
046  /** Returns the number of bytes read. */
047  public long getCount() {
048    return count;
049  }
050
051  @Override public int read() throws IOException {
052    int result = in.read();
053    if (result != -1) {
054      count++;
055    }
056    return result;
057  }
058
059  @Override public int read(byte[] b, int off, int len) throws IOException {
060    int result = in.read(b, off, len);
061    if (result != -1) {
062      count += result;
063    }
064    return result;
065  }
066
067  @Override public long skip(long n) throws IOException {
068    long result = in.skip(n);
069    count += result;
070    return result;
071  }
072
073  @Override public synchronized void mark(int readlimit) {
074    in.mark(readlimit);
075    mark = count;
076    // it's okay to mark even if mark isn't supported, as reset won't work
077  }
078
079  @Override public synchronized void reset() throws IOException {
080    if (!in.markSupported()) {
081      throw new IOException("Mark not supported");
082    }
083    if (mark == -1) {
084      throw new IOException("Mark not set");
085    }
086
087    in.reset();
088    count = mark;
089  }
090}