001/* 002 * Copyright (C) 2007 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 005 * in compliance with the License. You may obtain a copy of the License at 006 * 007 * http://www.apache.org/licenses/LICENSE-2.0 008 * 009 * Unless required by applicable law or agreed to in writing, software distributed under the License 010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express 011 * or implied. See the License for the specific language governing permissions and limitations under 012 * the License. 013 */ 014 015package com.google.common.io; 016 017import static com.google.common.base.Preconditions.checkNotNull; 018 019import com.google.common.annotations.GwtIncompatible; 020import com.google.common.annotations.J2ktIncompatible; 021import java.io.FilterInputStream; 022import java.io.IOException; 023import java.io.InputStream; 024 025/** 026 * An {@link InputStream} that counts the number of bytes read. 027 * 028 * @author Chris Nokleberg 029 * @since 1.0 030 */ 031@J2ktIncompatible 032@GwtIncompatible 033@ElementTypesAreNonnullByDefault 034public final class CountingInputStream extends FilterInputStream { 035 036 private long count; 037 private long mark = -1; 038 039 /** 040 * Wraps another input stream, counting the number of bytes read. 041 * 042 * @param in the input stream to be wrapped 043 */ 044 public CountingInputStream(InputStream in) { 045 super(checkNotNull(in)); 046 } 047 048 /** Returns the number of bytes read. */ 049 public long getCount() { 050 return count; 051 } 052 053 @Override 054 public int read() throws IOException { 055 int result = in.read(); 056 if (result != -1) { 057 count++; 058 } 059 return result; 060 } 061 062 @Override 063 public int read(byte[] b, int off, int len) throws IOException { 064 int result = in.read(b, off, len); 065 if (result != -1) { 066 count += result; 067 } 068 return result; 069 } 070 071 @Override 072 public long skip(long n) throws IOException { 073 long result = in.skip(n); 074 count += result; 075 return result; 076 } 077 078 @Override 079 public synchronized void mark(int readlimit) { 080 in.mark(readlimit); 081 mark = count; 082 // it's okay to mark even if mark isn't supported, as reset won't work 083 } 084 085 @Override 086 public synchronized void reset() throws IOException { 087 if (!in.markSupported()) { 088 throw new IOException("Mark not supported"); 089 } 090 if (mark == -1) { 091 throw new IOException("Mark not set"); 092 } 093 094 in.reset(); 095 count = mark; 096 } 097}