001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.io.input;
018
019 import java.io.IOException;
020 import java.io.InputStream;
021
022 /**
023 * A decorating input stream that counts the number of bytes that have passed
024 * through the stream so far.
025 * <p>
026 * A typical use case would be during debugging, to ensure that data is being
027 * read as expected.
028 *
029 * @version $Id: CountingInputStream.java 1304052 2012-03-22 20:55:29Z ggregory $
030 */
031 public class CountingInputStream extends ProxyInputStream {
032
033 /** The count of bytes that have passed. */
034 private long count;
035
036 /**
037 * Constructs a new CountingInputStream.
038 *
039 * @param in the InputStream to delegate to
040 */
041 public CountingInputStream(InputStream in) {
042 super(in);
043 }
044
045 //-----------------------------------------------------------------------
046
047 /**
048 * Skips the stream over the specified number of bytes, adding the skipped
049 * amount to the count.
050 *
051 * @param length the number of bytes to skip
052 * @return the actual number of bytes skipped
053 * @throws IOException if an I/O error occurs
054 * @see java.io.InputStream#skip(long)
055 */
056 @Override
057 public synchronized long skip(final long length) throws IOException {
058 final long skip = super.skip(length);
059 this.count += skip;
060 return skip;
061 }
062
063 /**
064 * Adds the number of read bytes to the count.
065 *
066 * @param n number of bytes read, or -1 if no more bytes are available
067 * @since 2.0
068 */
069 @Override
070 protected synchronized void afterRead(int n) {
071 if (n != -1) {
072 this.count += n;
073 }
074 }
075
076 //-----------------------------------------------------------------------
077 /**
078 * The number of bytes that have passed through this stream.
079 * <p>
080 * NOTE: From v1.3 this method throws an ArithmeticException if the
081 * count is greater than can be expressed by an <code>int</code>.
082 * See {@link #getByteCount()} for a method using a <code>long</code>.
083 *
084 * @return the number of bytes accumulated
085 * @throws ArithmeticException if the byte count is too large
086 */
087 public int getCount() {
088 long result = getByteCount();
089 if (result > Integer.MAX_VALUE) {
090 throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
091 }
092 return (int) result;
093 }
094
095 /**
096 * Set the byte count back to 0.
097 * <p>
098 * NOTE: From v1.3 this method throws an ArithmeticException if the
099 * count is greater than can be expressed by an <code>int</code>.
100 * See {@link #resetByteCount()} for a method using a <code>long</code>.
101 *
102 * @return the count previous to resetting
103 * @throws ArithmeticException if the byte count is too large
104 */
105 public int resetCount() {
106 long result = resetByteCount();
107 if (result > Integer.MAX_VALUE) {
108 throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
109 }
110 return (int) result;
111 }
112
113 /**
114 * The number of bytes that have passed through this stream.
115 * <p>
116 * NOTE: This method is an alternative for <code>getCount()</code>
117 * and was added because that method returns an integer which will
118 * result in incorrect count for files over 2GB.
119 *
120 * @return the number of bytes accumulated
121 * @since 1.3
122 */
123 public synchronized long getByteCount() {
124 return this.count;
125 }
126
127 /**
128 * Set the byte count back to 0.
129 * <p>
130 * NOTE: This method is an alternative for <code>resetCount()</code>
131 * and was added because that method returns an integer which will
132 * result in incorrect count for files over 2GB.
133 *
134 * @return the count previous to resetting
135 * @since 1.3
136 */
137 public synchronized long resetByteCount() {
138 long tmp = this.count;
139 this.count = 0;
140 return tmp;
141 }
142
143 }