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 * 028 */ 029public class CountingOutputStream extends ProxyOutputStream { 030 031 /** The count of bytes that have passed. */ 032 private long count = 0; 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 /** 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 /** 058 * The number of bytes that have passed through this stream. 059 * <p> 060 * NOTE: From v1.3 this method throws an ArithmeticException if the 061 * count is greater than can be expressed by an <code>int</code>. 062 * See {@link #getByteCount()} for a method using a <code>long</code>. 063 * 064 * @return the number of bytes accumulated 065 * @throws ArithmeticException if the byte count is too large 066 */ 067 public int getCount() { 068 final long result = getByteCount(); 069 if (result > Integer.MAX_VALUE) { 070 throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int"); 071 } 072 return (int) result; 073 } 074 075 /** 076 * Set the byte count back to 0. 077 * <p> 078 * NOTE: From v1.3 this method throws an ArithmeticException if the 079 * count is greater than can be expressed by an <code>int</code>. 080 * See {@link #resetByteCount()} for a method using a <code>long</code>. 081 * 082 * @return the count previous to resetting 083 * @throws ArithmeticException if the byte count is too large 084 */ 085 public int resetCount() { 086 final long result = resetByteCount(); 087 if (result > Integer.MAX_VALUE) { 088 throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int"); 089 } 090 return (int) result; 091 } 092 093 /** 094 * The number of bytes that have passed through this stream. 095 * <p> 096 * NOTE: This method is an alternative for <code>getCount()</code>. 097 * It was added because that method returns an integer which will 098 * result in incorrect count for files over 2GB. 099 * 100 * @return the number of bytes accumulated 101 * @since 1.3 102 */ 103 public synchronized long getByteCount() { 104 return this.count; 105 } 106 107 /** 108 * Set the byte count back to 0. 109 * <p> 110 * NOTE: This method is an alternative for <code>resetCount()</code>. 111 * It was added because that method returns an integer which will 112 * result in incorrect count for files over 2GB. 113 * 114 * @return the count previous to resetting 115 * @since 1.3 116 */ 117 public synchronized long resetByteCount() { 118 final long tmp = this.count; 119 this.count = 0; 120 return tmp; 121 } 122 123}