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.output; 018 019import java.io.OutputStream; 020 021/** 022 * A decorating output stream that counts the number of bytes that have passed 023 * through the stream so far. 024 * <p> 025 * A typical use case would be during debugging, to ensure that data is being 026 * written as expected. 027 * </p> 028 */ 029public class CountingOutputStream extends ProxyOutputStream { 030 031 /** The count of bytes that have passed. */ 032 private long count; 033 034 /** 035 * Constructs a new CountingOutputStream. 036 * 037 * @param out the OutputStream to write to 038 */ 039 public CountingOutputStream(final OutputStream out) { 040 super(out); 041 } 042 043 044 /** 045 * Updates the count with the number of bytes that are being written. 046 * 047 * @param n number of bytes to be written to the stream 048 * @since 2.0 049 */ 050 @Override 051 protected synchronized void beforeWrite(final int n) { 052 count += n; 053 } 054 055 /** 056 * The number of bytes that have passed through this stream. 057 * <p> 058 * NOTE: This method is an alternative for {@code getCount()}. 059 * It was added because that method returns an integer which will 060 * result in incorrect count for files over 2GB. 061 * 062 * @return the number of bytes accumulated 063 * @since 1.3 064 */ 065 public synchronized long getByteCount() { 066 return this.count; 067 } 068 069 /** 070 * The number of bytes that have passed through this stream. 071 * <p> 072 * NOTE: From v1.3 this method throws an ArithmeticException if the 073 * count is greater than can be expressed by an {@code int}. 074 * See {@link #getByteCount()} for a method using a {@code long}. 075 * 076 * @return the number of bytes accumulated 077 * @throws ArithmeticException if the byte count is too large 078 */ 079 public int getCount() { 080 final long result = getByteCount(); 081 if (result > Integer.MAX_VALUE) { 082 throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int"); 083 } 084 return (int) result; 085 } 086 087 /** 088 * Set the byte count back to 0. 089 * <p> 090 * NOTE: This method is an alternative for {@code resetCount()}. 091 * It was added because that method returns an integer which will 092 * result in incorrect count for files over 2GB. 093 * 094 * @return the count previous to resetting 095 * @since 1.3 096 */ 097 public synchronized long resetByteCount() { 098 final long tmp = this.count; 099 this.count = 0; 100 return tmp; 101 } 102 103 /** 104 * Set the byte count back to 0. 105 * <p> 106 * NOTE: From v1.3 this method throws an ArithmeticException if the 107 * count is greater than can be expressed by an {@code int}. 108 * See {@link #resetByteCount()} for a method using a {@code long}. 109 * 110 * @return the count previous to resetting 111 * @throws ArithmeticException if the byte count is too large 112 */ 113 public int resetCount() { 114 final long result = resetByteCount(); 115 if (result > Integer.MAX_VALUE) { 116 throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int"); 117 } 118 return (int) result; 119 } 120 121}