1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 *
19 */
20 package org.apache.mina.core.buffer;
21
22 /**
23 * Provides utility methods to dump an {@link IoBuffer} into a hex formatted
24 * string.
25 *
26 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
27 */
28 class IoBufferHexDumper {
29
30 /**
31 * The high digits lookup table.
32 */
33 private static final byte[] highDigits;
34
35 /**
36 * The low digits lookup table.
37 */
38 private static final byte[] lowDigits;
39
40 /**
41 * Initialize lookup tables.
42 */
43 static {
44 final byte[] digits = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
45
46 int i;
47 byte[] high = new byte[256];
48 byte[] low = new byte[256];
49
50 for (i = 0; i < 256; i++) {
51 high[i] = digits[i >>> 4];
52 low[i] = digits[i & 0x0F];
53 }
54
55 highDigits = high;
56 lowDigits = low;
57 }
58
59 /**
60 * Dumps an {@link IoBuffer} to a hex formatted string.
61 *
62 * @param in the buffer to dump
63 * @param lengthLimit the limit at which hex dumping will stop
64 * @return a hex formatted string representation of the <i>in</i> {@link IoBuffer}.
65 */
66 public static String getHexdump(IoBuffer in, int lengthLimit) {
67 if (lengthLimit == 0) {
68 throw new IllegalArgumentException("lengthLimit: " + lengthLimit + " (expected: 1+)");
69 }
70
71 int limit = in.limit();
72 int pos = in.position();
73
74 boolean truncate = limit - pos > lengthLimit;
75 int size;
76 if (truncate) {
77 size = lengthLimit;
78 } else {
79 size = limit - pos;
80 }
81
82 if (size == 0) {
83 return "empty";
84 }
85
86 StringBuilder out = new StringBuilder(size * 3 + 3);
87
88 // fill the first
89 int byteValue = in.get(pos++) & 0xFF;
90 out.append((char) highDigits[byteValue]);
91 out.append((char) lowDigits[byteValue]);
92
93 // and the others, too
94 for (; pos < limit; ) {
95 out.append(' ');
96 byteValue = in.get(pos++) & 0xFF;
97 out.append((char) highDigits[byteValue]);
98 out.append((char) lowDigits[byteValue]);
99 }
100
101 if (truncate) {
102 out.append("...");
103 }
104
105 return out.toString();
106 }
107 }