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 com.google.common.annotations.J2ktIncompatible;
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@J2ktIncompatible
032@GwtIncompatible
033public final class CountingInputStream extends FilterInputStream {
034
035  private long count;
036  private long mark = -1;
037
038  /**
039   * Wraps another input stream, counting the number of bytes read.
040   *
041   * @param in the input stream to be wrapped
042   */
043  public CountingInputStream(InputStream in) {
044    super(checkNotNull(in));
045  }
046
047  /** Returns the number of bytes read. */
048  public long getCount() {
049    return count;
050  }
051
052  @Override
053  public int read() throws IOException {
054    int result = in.read();
055    if (result != -1) {
056      count++;
057    }
058    return result;
059  }
060
061  @Override
062  public int read(byte[] b, int off, int len) throws IOException {
063    int result = in.read(b, off, len);
064    if (result != -1) {
065      count += result;
066    }
067    return result;
068  }
069
070  @Override
071  public long skip(long n) throws IOException {
072    long result = in.skip(n);
073    count += result;
074    return result;
075  }
076
077  @Override
078  public synchronized void mark(int readlimit) {
079    in.mark(readlimit);
080    mark = count;
081    // it's okay to mark even if mark isn't supported, as reset won't work
082  }
083
084  @Override
085  public synchronized void reset() throws IOException {
086    if (!in.markSupported()) {
087      throw new IOException("Mark not supported");
088    }
089    if (mark == -1) {
090      throw new IOException("Mark not set");
091    }
092
093    in.reset();
094    count = mark;
095  }
096}