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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    * 
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   * 
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.io.input;
18  
19  import java.io.IOException;
20  import java.io.InputStream;
21  
22  /**
23   * A decorating input stream that counts the number of bytes that have passed
24   * through the stream so far.
25   * <p>
26   * A typical use case would be during debugging, to ensure that data is being
27   * read as expected.
28   *
29   * @author Marcelo Liberato
30   * @version $Id: CountingInputStream.java 471628 2006-11-06 04:06:45Z bayard $
31   */
32  public class CountingInputStream extends ProxyInputStream {
33  
34      /** The count of bytes that have passed. */
35      private long count;
36  
37      /**
38       * Constructs a new CountingInputStream.
39       *
40       * @param in  the InputStream to delegate to
41       */
42      public CountingInputStream(InputStream in) {
43          super(in);
44      }
45  
46      //-----------------------------------------------------------------------
47      /**
48       * Reads a number of bytes into the byte array, keeping count of the
49       * number read.
50       *
51       * @param b  the buffer into which the data is read, not null
52       * @return the total number of bytes read into the buffer, -1 if end of stream
53       * @throws IOException if an I/O error occurs
54       * @see java.io.InputStream#read(byte[]) 
55       */
56      public int read(byte[] b) throws IOException {
57          int found = super.read(b);
58          this.count += (found >= 0) ? found : 0;
59          return found;
60      }
61  
62      /**
63       * Reads a number of bytes into the byte array at a specific offset,
64       * keeping count of the number read.
65       *
66       * @param b  the buffer into which the data is read, not null
67       * @param off  the start offset in the buffer
68       * @param len  the maximum number of bytes to read
69       * @return the total number of bytes read into the buffer, -1 if end of stream
70       * @throws IOException if an I/O error occurs
71       * @see java.io.InputStream#read(byte[], int, int)
72       */
73      public int read(byte[] b, int off, int len) throws IOException {
74          int found = super.read(b, off, len);
75          this.count += (found >= 0) ? found : 0;
76          return found;
77      }
78  
79      /**
80       * Reads the next byte of data adding to the count of bytes received
81       * if a byte is successfully read. 
82       *
83       * @return the byte read, -1 if end of stream
84       * @throws IOException if an I/O error occurs
85       * @see java.io.InputStream#read()
86       */
87      public int read() throws IOException {
88          int found = super.read();
89          this.count += (found >= 0) ? 1 : 0;
90          return found;
91      }
92  
93      /**
94       * Skips the stream over the specified number of bytes, adding the skipped
95       * amount to the count.
96       *
97       * @param length  the number of bytes to skip
98       * @return the actual number of bytes skipped
99       * @throws IOException if an I/O error occurs
100      * @see java.io.InputStream#skip(long)
101      */
102     public long skip(final long length) throws IOException {
103         final long skip = super.skip(length);
104         this.count += skip;
105         return skip;
106     }
107 
108     //-----------------------------------------------------------------------
109     /**
110      * The number of bytes that have passed through this stream.
111      * <p>
112      * NOTE: From v1.3 this method throws an ArithmeticException if the
113      * count is greater than can be expressed by an <code>int</code>.
114      * See {@link #getByteCount()} for a method using a <code>long</code>.
115      *
116      * @return the number of bytes accumulated
117      * @throws ArithmeticException if the byte count is too large
118      */
119     public synchronized int getCount() {
120         long result = getByteCount();
121         if (result > Integer.MAX_VALUE) {
122             throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
123         }
124         return (int) result;
125     }
126 
127     /** 
128      * Set the byte count back to 0. 
129      * <p>
130      * NOTE: From v1.3 this method throws an ArithmeticException if the
131      * count is greater than can be expressed by an <code>int</code>.
132      * See {@link #resetByteCount()} for a method using a <code>long</code>.
133      *
134      * @return the count previous to resetting
135      * @throws ArithmeticException if the byte count is too large
136      */
137     public synchronized int resetCount() {
138         long result = resetByteCount();
139         if (result > Integer.MAX_VALUE) {
140             throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
141         }
142         return (int) result;
143     }
144 
145     /**
146      * The number of bytes that have passed through this stream.
147      * <p>
148      * NOTE: This method is an alternative for <code>getCount()</code>
149      * and was added because that method returns an integer which will
150      * result in incorrect count for files over 2GB.
151      *
152      * @return the number of bytes accumulated
153      * @since Commons IO 1.3
154      */
155     public synchronized long getByteCount() {
156         return this.count;
157     }
158 
159     /** 
160      * Set the byte count back to 0. 
161      * <p>
162      * NOTE: This method is an alternative for <code>resetCount()</code>
163      * and was added because that method returns an integer which will
164      * result in incorrect count for files over 2GB.
165      *
166      * @return the count previous to resetting
167      * @since Commons IO 1.3
168      */
169     public synchronized long resetByteCount() {
170         long tmp = this.count;
171         this.count = 0;
172         return tmp;
173     }
174 
175 }