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 string.
24 *
25 * @author The Apache MINA Project (dev@mina.apache.org)
26 */
27 class IoBufferHexDumper {
28
29 /**
30 * The high digits lookup table.
31 */
32 private static final byte[] highDigits;
33
34 /**
35 * The low digits lookup table.
36 */
37 private static final byte[] lowDigits;
38
39 /**
40 * Initialize lookup tables.
41 */
42 static {
43 final byte[] digits = { '0', '1', '2', '3', '4', '5', '6', '7', '8',
44 '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
69 + " (expected: 1+)");
70 }
71
72 boolean truncate = in.remaining() > lengthLimit;
73 int size;
74 if (truncate) {
75 size = lengthLimit;
76 } else {
77 size = in.remaining();
78 }
79
80 if (size == 0) {
81 return "empty";
82 }
83
84 StringBuilder out = new StringBuilder(size * 3 + 3);
85
86 int mark = in.position();
87
88 // fill the first
89 int byteValue = in.get() & 0xFF;
90 out.append((char) highDigits[byteValue]);
91 out.append((char) lowDigits[byteValue]);
92 size--;
93
94 // and the others, too
95 for (; size > 0; size--) {
96 out.append(' ');
97 byteValue = in.get() & 0xFF;
98 out.append((char) highDigits[byteValue]);
99 out.append((char) lowDigits[byteValue]);
100 }
101
102 in.position(mark);
103
104 if (truncate) {
105 out.append("...");
106 }
107
108 return out.toString();
109 }
110 }