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