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 */ 017package org.apache.commons.io.input; 018 019import static org.apache.commons.io.IOUtils.EOF; 020 021import java.io.IOException; 022import java.io.InputStream; 023 024/** 025 * A decorating input stream that counts the number of bytes that have passed 026 * through the stream so far. 027 * <p> 028 * A typical use case would be during debugging, to ensure that data is being 029 * read as expected. 030 * </p> 031 */ 032public class CountingInputStream extends ProxyInputStream { 033 034 /** The count of bytes that have passed. */ 035 private long count; 036 037 /** 038 * Constructs a new CountingInputStream. 039 * 040 * @param in the InputStream to delegate to 041 */ 042 public CountingInputStream(final InputStream in) { 043 super(in); 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(final int n) { 071 if (n != EOF) { 072 this.count += n; 073 } 074 } 075 076 /** 077 * The number of bytes that have passed through this stream. 078 * <p> 079 * NOTE: From v1.3 this method throws an ArithmeticException if the 080 * count is greater than can be expressed by an {@code int}. 081 * See {@link #getByteCount()} for a method using a {@code long}. 082 * 083 * @return the number of bytes accumulated 084 * @throws ArithmeticException if the byte count is too large 085 */ 086 public int getCount() { 087 final long result = getByteCount(); 088 if (result > Integer.MAX_VALUE) { 089 throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int"); 090 } 091 return (int) result; 092 } 093 094 /** 095 * Set the byte count back to 0. 096 * <p> 097 * NOTE: From v1.3 this method throws an ArithmeticException if the 098 * count is greater than can be expressed by an {@code int}. 099 * See {@link #resetByteCount()} for a method using a {@code long}. 100 * 101 * @return the count previous to resetting 102 * @throws ArithmeticException if the byte count is too large 103 */ 104 public int resetCount() { 105 final long result = resetByteCount(); 106 if (result > Integer.MAX_VALUE) { 107 throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int"); 108 } 109 return (int) result; 110 } 111 112 /** 113 * The number of bytes that have passed through this stream. 114 * <p> 115 * NOTE: This method is an alternative for {@code getCount()} 116 * and was added because that method returns an integer which will 117 * result in incorrect count for files over 2GB. 118 * 119 * @return the number of bytes accumulated 120 * @since 1.3 121 */ 122 public synchronized long getByteCount() { 123 return this.count; 124 } 125 126 /** 127 * Set the byte count back to 0. 128 * <p> 129 * NOTE: This method is an alternative for {@code resetCount()} 130 * and was added because that method returns an integer which will 131 * result in incorrect count for files over 2GB. 132 * 133 * @return the count previous to resetting 134 * @since 1.3 135 */ 136 public synchronized long resetByteCount() { 137 final long tmp = this.count; 138 this.count = 0; 139 return tmp; 140 } 141 142}