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 * 029 */ 030public class CountingOutputStream extends ProxyOutputStream { 031 032 /** The count of bytes that have passed. */ 033 private long count; 034 035 /** 036 * Constructs a new CountingOutputStream. 037 * 038 * @param out the OutputStream to write to 039 */ 040 public CountingOutputStream( final OutputStream out ) { 041 super(out); 042 } 043 044 045 /** 046 * Updates the count with the number of bytes that are being written. 047 * 048 * @param n number of bytes to be written to the stream 049 * @since 2.0 050 */ 051 @Override 052 protected synchronized void beforeWrite(final int n) { 053 count += n; 054 } 055 056 /** 057 * The number of bytes that have passed through this stream. 058 * <p> 059 * NOTE: From v1.3 this method throws an ArithmeticException if the 060 * count is greater than can be expressed by an {@code int}. 061 * See {@link #getByteCount()} for a method using a {@code long}. 062 * 063 * @return the number of bytes accumulated 064 * @throws ArithmeticException if the byte count is too large 065 */ 066 public int getCount() { 067 final long result = getByteCount(); 068 if (result > Integer.MAX_VALUE) { 069 throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int"); 070 } 071 return (int) result; 072 } 073 074 /** 075 * Set the byte count back to 0. 076 * <p> 077 * NOTE: From v1.3 this method throws an ArithmeticException if the 078 * count is greater than can be expressed by an {@code int}. 079 * See {@link #resetByteCount()} for a method using a {@code long}. 080 * 081 * @return the count previous to resetting 082 * @throws ArithmeticException if the byte count is too large 083 */ 084 public int resetCount() { 085 final long result = resetByteCount(); 086 if (result > Integer.MAX_VALUE) { 087 throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int"); 088 } 089 return (int) result; 090 } 091 092 /** 093 * The number of bytes that have passed through this stream. 094 * <p> 095 * NOTE: This method is an alternative for {@code getCount()}. 096 * It was added because that method returns an integer which will 097 * result in incorrect count for files over 2GB. 098 * 099 * @return the number of bytes accumulated 100 * @since 1.3 101 */ 102 public synchronized long getByteCount() { 103 return this.count; 104 } 105 106 /** 107 * Set the byte count back to 0. 108 * <p> 109 * NOTE: This method is an alternative for {@code resetCount()}. 110 * It was added because that method returns an integer which will 111 * result in incorrect count for files over 2GB. 112 * 113 * @return the count previous to resetting 114 * @since 1.3 115 */ 116 public synchronized long resetByteCount() { 117 final long tmp = this.count; 118 this.count = 0; 119 return tmp; 120 } 121 122}