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 * </p> 062 * 063 * @return the number of bytes accumulated 064 * @since 1.3 065 */ 066 public synchronized long getByteCount() { 067 return this.count; 068 } 069 070 /** 071 * Gets the number of bytes that have passed through this stream. 072 * <p> 073 * NOTE: From v1.3 this method throws an ArithmeticException if the 074 * count is greater than can be expressed by an {@code int}. 075 * See {@link #getByteCount()} for a method using a {@code long}. 076 * </p> 077 * 078 * @return the number of bytes accumulated 079 * @throws ArithmeticException if the byte count is too large 080 */ 081 public int getCount() { 082 final long result = getByteCount(); 083 if (result > Integer.MAX_VALUE) { 084 throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int"); 085 } 086 return (int) result; 087 } 088 089 /** 090 * Sets the byte count back to 0. 091 * <p> 092 * NOTE: This method is an alternative for {@code resetCount()}. 093 * It was added because that method returns an integer which will 094 * result in incorrect count for files over 2GB. 095 * </p> 096 * 097 * @return the count previous to resetting 098 * @since 1.3 099 */ 100 public synchronized long resetByteCount() { 101 final long tmp = this.count; 102 this.count = 0; 103 return tmp; 104 } 105 106 /** 107 * Sets the byte count back to 0. 108 * <p> 109 * NOTE: From v1.3 this method throws an ArithmeticException if the 110 * count is greater than can be expressed by an {@code int}. 111 * See {@link #resetByteCount()} for a method using a {@code long}. 112 * </p> 113 * 114 * @return the count previous to resetting 115 * @throws ArithmeticException if the byte count is too large 116 */ 117 public int resetCount() { 118 final long result = resetByteCount(); 119 if (result > Integer.MAX_VALUE) { 120 throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int"); 121 } 122 return (int) result; 123 } 124 125}