1 /* 2 * Copyright (C) 2007 The Guava Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.common.io; 18 19 import com.google.common.annotations.Beta; 20 21 import java.io.FilterInputStream; 22 import java.io.IOException; 23 import java.io.InputStream; 24 25 import javax.annotation.Nullable; 26 27 /** 28 * An {@link InputStream} that counts the number of bytes read. 29 * 30 * @author Chris Nokleberg 31 * @since 1.0 32 */ 33 @Beta 34 public final class CountingInputStream extends FilterInputStream { 35 36 private long count; 37 private long mark = -1; 38 39 /** 40 * Wraps another input stream, counting the number of bytes read. 41 * 42 * @param in the input stream to be wrapped 43 */ CountingInputStream(@ullable InputStream in)44 public CountingInputStream(@Nullable InputStream in) { 45 super(in); 46 } 47 48 /** Returns the number of bytes read. */ getCount()49 public long getCount() { 50 return count; 51 } 52 read()53 @Override public int read() throws IOException { 54 int result = in.read(); 55 if (result != -1) { 56 count++; 57 } 58 return result; 59 } 60 read(byte[] b, int off, int len)61 @Override public int read(byte[] b, int off, int len) throws IOException { 62 int result = in.read(b, off, len); 63 if (result != -1) { 64 count += result; 65 } 66 return result; 67 } 68 skip(long n)69 @Override public long skip(long n) throws IOException { 70 long result = in.skip(n); 71 count += result; 72 return result; 73 } 74 mark(int readlimit)75 @Override public synchronized void mark(int readlimit) { 76 in.mark(readlimit); 77 mark = count; 78 // it's okay to mark even if mark isn't supported, as reset won't work 79 } 80 reset()81 @Override public synchronized void reset() throws IOException { 82 if (!in.markSupported()) { 83 throw new IOException("Mark not supported"); 84 } 85 if (mark == -1) { 86 throw new IOException("Mark not set"); 87 } 88 89 in.reset(); 90 count = mark; 91 } 92 } 93