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.FilterOutputStream; 022import java.io.IOException; 023import java.io.OutputStream; 024 025/** 026 * An OutputStream that counts the number of bytes written. 027 * 028 * @author Chris Nokleberg 029 * @since 1.0 030 */ 031@J2ktIncompatible 032@GwtIncompatible 033@ElementTypesAreNonnullByDefault 034public final class CountingOutputStream extends FilterOutputStream { 035 036 private long count; 037 038 /** 039 * Wraps another output stream, counting the number of bytes written. 040 * 041 * @param out the output stream to be wrapped 042 */ 043 public CountingOutputStream(OutputStream out) { 044 super(checkNotNull(out)); 045 } 046 047 /** Returns the number of bytes written. */ 048 public long getCount() { 049 return count; 050 } 051 052 @Override 053 public void write(byte[] b, int off, int len) throws IOException { 054 out.write(b, off, len); 055 count += len; 056 } 057 058 @Override 059 public void write(int b) throws IOException { 060 out.write(b); 061 count++; 062 } 063 064 // Overriding close() because FilterOutputStream's close() method pre-JDK8 has bad behavior: 065 // it silently ignores any exception thrown by flush(). Instead, just close the delegate stream. 066 // It should flush itself if necessary. 067 @Override 068 public void close() throws IOException { 069 out.close(); 070 } 071}