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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.output;
18  
19  import java.io.OutputStream;
20  
21  /**
22   * A decorating output stream that counts the number of bytes that have passed
23   * through the stream so far.
24   * <p>
25   * A typical use case would be during debugging, to ensure that data is being
26   * written as expected.
27   *
28   * @version $Id: CountingOutputStream.java 1415850 2012-11-30 20:51:39Z ggregory $
29   */
30  public class CountingOutputStream extends ProxyOutputStream {
31  
32      /** The count of bytes that have passed. */
33      private long count = 0;
34  
35      /**
36       * Constructs a new CountingOutputStream.
37       * 
38       * @param out  the OutputStream to write to
39       */
40      public CountingOutputStream( final OutputStream out ) {
41          super(out);
42      }
43  
44      //-----------------------------------------------------------------------
45  
46      /**
47       * Updates the count with the number of bytes that are being written.
48       *
49       * @param n number of bytes to be written to the stream
50       * @since 2.0
51       */
52      @Override
53      protected synchronized void beforeWrite(final int n) {
54          count += n;
55      }
56  
57      //-----------------------------------------------------------------------
58      /**
59       * The number of bytes that have passed through this stream.
60       * <p>
61       * NOTE: From v1.3 this method throws an ArithmeticException if the
62       * count is greater than can be expressed by an <code>int</code>.
63       * See {@link #getByteCount()} for a method using a <code>long</code>.
64       *
65       * @return the number of bytes accumulated
66       * @throws ArithmeticException if the byte count is too large
67       */
68      public int getCount() {
69          final long result = getByteCount();
70          if (result > Integer.MAX_VALUE) {
71              throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
72          }
73          return (int) result;
74      }
75  
76      /** 
77       * Set the byte count back to 0. 
78       * <p>
79       * NOTE: From v1.3 this method throws an ArithmeticException if the
80       * count is greater than can be expressed by an <code>int</code>.
81       * See {@link #resetByteCount()} for a method using a <code>long</code>.
82       *
83       * @return the count previous to resetting
84       * @throws ArithmeticException if the byte count is too large
85       */
86      public int resetCount() {
87          final long result = resetByteCount();
88          if (result > Integer.MAX_VALUE) {
89              throw new ArithmeticException("The byte count " + result + " is too large to be converted to an int");
90          }
91          return (int) result;
92      }
93  
94      /**
95       * The number of bytes that have passed through this stream.
96       * <p>
97       * NOTE: This method is an alternative for <code>getCount()</code>.
98       * It was added because that method returns an integer which will
99       * result in incorrect count for files over 2GB.
100      *
101      * @return the number of bytes accumulated
102      * @since 1.3
103      */
104     public synchronized long getByteCount() {
105         return this.count;
106     }
107 
108     /** 
109      * Set the byte count back to 0. 
110      * <p>
111      * NOTE: This method is an alternative for <code>resetCount()</code>.
112      * It was added because that method returns an integer which will
113      * result in incorrect count for files over 2GB.
114      *
115      * @return the count previous to resetting
116      * @since 1.3
117      */
118     public synchronized long resetByteCount() {
119         final long tmp = this.count;
120         this.count = 0;
121         return tmp;
122     }
123 
124 }