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
017 package com.google.common.io;
018
019 import com.google.common.annotations.Beta;
020
021 import java.io.FilterInputStream;
022 import java.io.IOException;
023 import 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
032 public 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 }