001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.io;
018
019 import java.io.IOException;
020 import java.io.OutputStream;
021
022 /**
023 * Dumps data in hexadecimal format.
024 * <p>
025 * Provides a single function to take an array of bytes and display it
026 * in hexadecimal form.
027 * <p>
028 * Origin of code: POI.
029 *
030 * @author Scott Sanders
031 * @author Marc Johnson
032 * @version $Id: HexDump.java 736507 2009-01-22 00:52:15Z jukka $
033 */
034 public class HexDump {
035
036 /**
037 * Instances should NOT be constructed in standard programming.
038 */
039 public HexDump() {
040 super();
041 }
042
043 /**
044 * Dump an array of bytes to an OutputStream. The output is formatted
045 * for human inspection, with a hexadecimal offset followed by the
046 * hexadecimal values of the next 16 bytes of data and the printable ASCII
047 * characters (if any) that those bytes represent printed per each line
048 * of output.
049 * <p>
050 * The offset argument specifies the start offset of the data array
051 * within a larger entity like a file or an incoming stream. For example,
052 * if the data array contains the third kibibyte of a file, then the
053 * offset argument should be set to 2048. The offset value printed
054 * at the beginning of each line indicates where in that larger entity
055 * the first byte on that line is located.
056 * <p>
057 * All bytes between the given index (inclusive) and the end of the
058 * data array are dumped.
059 *
060 * @param data the byte array to be dumped
061 * @param offset offset of the byte array within a larger entity
062 * @param stream the OutputStream to which the data is to be
063 * written
064 * @param index initial index into the byte array
065 *
066 * @throws IOException is thrown if anything goes wrong writing
067 * the data to stream
068 * @throws ArrayIndexOutOfBoundsException if the index is
069 * outside the data array's bounds
070 * @throws IllegalArgumentException if the output stream is null
071 */
072
073 public static void dump(byte[] data, long offset,
074 OutputStream stream, int index)
075 throws IOException, ArrayIndexOutOfBoundsException,
076 IllegalArgumentException {
077
078 if ((index < 0) || (index >= data.length)) {
079 throw new ArrayIndexOutOfBoundsException(
080 "illegal index: " + index + " into array of length "
081 + data.length);
082 }
083 if (stream == null) {
084 throw new IllegalArgumentException("cannot write to nullstream");
085 }
086 long display_offset = offset + index;
087 StringBuilder buffer = new StringBuilder(74);
088
089 for (int j = index; j < data.length; j += 16) {
090 int chars_read = data.length - j;
091
092 if (chars_read > 16) {
093 chars_read = 16;
094 }
095 dump(buffer, display_offset).append(' ');
096 for (int k = 0; k < 16; k++) {
097 if (k < chars_read) {
098 dump(buffer, data[k + j]);
099 } else {
100 buffer.append(" ");
101 }
102 buffer.append(' ');
103 }
104 for (int k = 0; k < chars_read; k++) {
105 if ((data[k + j] >= ' ') && (data[k + j] < 127)) {
106 buffer.append((char) data[k + j]);
107 } else {
108 buffer.append('.');
109 }
110 }
111 buffer.append(EOL);
112 stream.write(buffer.toString().getBytes());
113 stream.flush();
114 buffer.setLength(0);
115 display_offset += chars_read;
116 }
117 }
118
119 /**
120 * The line-separator (initializes to "line.separator" system property.
121 */
122 public static final String EOL =
123 System.getProperty("line.separator");
124 private static final char[] _hexcodes =
125 {
126 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
127 'A', 'B', 'C', 'D', 'E', 'F'
128 };
129 private static final int[] _shifts =
130 {
131 28, 24, 20, 16, 12, 8, 4, 0
132 };
133
134 /**
135 * Dump a long value into a StringBuilder.
136 *
137 * @param _lbuffer the StringBuilder to dump the value in
138 * @param value the long value to be dumped
139 * @return StringBuilder containing the dumped value.
140 */
141 private static StringBuilder dump(StringBuilder _lbuffer, long value) {
142 for (int j = 0; j < 8; j++) {
143 _lbuffer
144 .append(_hexcodes[((int) (value >> _shifts[j])) & 15]);
145 }
146 return _lbuffer;
147 }
148
149 /**
150 * Dump a byte value into a StringBuilder.
151 *
152 * @param _cbuffer the StringBuilder to dump the value in
153 * @param value the byte value to be dumped
154 * @return StringBuilder containing the dumped value.
155 */
156 private static StringBuilder dump(StringBuilder _cbuffer, byte value) {
157 for (int j = 0; j < 2; j++) {
158 _cbuffer.append(_hexcodes[(value >> _shifts[j + 6]) & 15]);
159 }
160 return _cbuffer;
161 }
162
163 }