HexDump


1   /*
2    * Copyright (C) 2005 Alfresco, Inc.
3    *
4    * Licensed under the Mozilla Public License version 1.1 
5    * with a permitted attribution clause. You may obtain a
6    * copy of the License at
7    *
8    *   http://www.alfresco.org/legal/license.txt
9    *
10   * Unless required by applicable law or agreed to in writing,
11   * software distributed under the License is distributed on an
12   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
13   * either express or implied. See the License for the specific
14   * language governing permissions and limitations under the
15   * License.
16   */
17  package org.alfresco.filesys.util;
18  
19  import java.io.PrintStream  ;
20  
21  /**
22   * Hex dump class.
23   */
24  public final class HexDump
25  {
26  
27      /**
28       * Hex dump a byte array
29       * 
30       * @param byt Byte array to dump
31       * @param len Length of data to dump
32       * @param offset Offset to start data dump
33       */
34  
35      public static final void Dump(byte[] byt, int len, int offset)
36      {
37          Dump(byt, len, offset, System.out);
38      }
39  
40      /**
41       * Hex dump a byte array
42       * 
43       * @param byt Byte array to dump
44       * @param len Length of data to dump
45       * @param offset Offset to start data dump
46       * @param stream Output stream to dump the output to.
47       */
48  
49      public static final void Dump(byte[] byt, int len, int offset, PrintStream   stream)
50      {
51  
52          // Create buffers for the ASCII and Hex output
53  
54          StringBuffer   ascBuf = new StringBuffer  ();
55          StringBuffer   hexBuf = new StringBuffer  ();
56  
57          // Dump 16 byte blocks from the array until the length has been
58          // reached
59  
60          int dlen = 0;
61          int doff = offset;
62          String   posStr = null;
63  
64          while (dlen < len)
65          {
66  
67              // Reset the ASCII/Hex buffers
68  
69              ascBuf.setLength(0);
70              hexBuf.setLength(0);
71  
72              posStr = generatePositionString(doff);
73  
74              // Dump a block of data, update the data offset
75  
76              doff = generateLine(byt, doff, ascBuf, hexBuf);
77  
78              // Output the current record
79  
80              stream.print(posStr);
81              stream.print(hexBuf.toString());
82              stream.println(ascBuf.toString());
83  
84              // Update the dump length
85  
86              dlen += 16;
87          }
88      }
89  
90      /**
91       * Generate a hex string for the specified string
92       * 
93       * @param str String
94       * @return String
95       */
96      public static final String   hexString(String   str)
97      {
98          if (str != null)
99              return hexString(str.getBytes());
100         return "";
101     }
102 
103     /**
104      * Generate a hex string for the specified string
105      * 
106      * @param str String
107      * @param gap String
108      * @return String
109      */
110     public static final String   hexString(String   str, String   gap)
111     {
112         if (str != null)
113             return hexString(str.getBytes(), gap);
114         return "";
115     }
116 
117     /**
118      * Generate a hex string for the specified bytes
119      * 
120      * @param buf byte[]
121      * @return String
122      */
123     public static final String   hexString(byte[] buf)
124     {
125         return hexString(buf, buf.length, null);
126     }
127 
128     /**
129      * Generate a hex string for the specified bytes
130      * 
131      * @param buf byte[]
132      * @param gap String
133      * @return String
134      */
135     public static final String   hexString(byte[] buf, String   gap)
136     {
137         return hexString(buf, buf.length, gap);
138     }
139 
140     /**
141      * Generate a hex string for the specified bytes
142      * 
143      * @param buf byte[]
144      * @param len int
145      * @param gap String
146      * @return String
147      */
148     public static final String   hexString(byte[] buf, int len, String   gap)
149     {
150 
151         // Check if the buffer is valid
152 
153         if (buf == null)
154             return "";
155 
156         // Create a string buffer for the hex string
157 
158         int buflen = buf.length * 2;
159         if (gap != null)
160             buflen += buf.length * gap.length();
161 
162         StringBuffer   hex = new StringBuffer  (buflen);
163 
164         // Convert the bytes to hex-ASCII
165 
166         for (int i = 0; i < len; i++)
167         {
168 
169             // Get the current byte
170 
171             int curbyt = (int) (buf[i] & 0x00FF);
172 
173             // Output the hex string
174 
175             hex.append(Integer.toHexString((curbyt & 0xF0) >> 4));
176             hex.append(Integer.toHexString(curbyt & 0x0F));
177 
178             // Add the gap string, if specified
179 
180             if (gap != null && i < (len - 1))
181                 hex.append(gap);
182         }
183 
184         // Return the hex-ASCII string
185 
186         return hex.toString();
187     }
188 
189     /**
190      * Generate a buffer position string
191      * 
192      * @param off int
193      * @return String
194      */
195     private static final String   generatePositionString(int off)
196     {
197 
198         // Create a buffer position string
199 
200         StringBuffer   posStr = new StringBuffer  ("" + off + " - ");
201         while (posStr.length() < 8)
202             posStr.insert(0, " ");
203 
204         // Return the string
205 
206         return posStr.toString();
207     }
208 
209     /**
210      * Output a single line of the hex dump to a debug device
211      * 
212      * @param byt Byte array to dump
213      * @param off Offset to start data dump
214      * @param ascBuf Buffer for ASCII output
215      * @param hexBuf Buffer for Hex output
216      * @return New offset value
217      */
218 
219     private static final int generateLine(byte[] byt, int off, StringBuffer   ascBuf, StringBuffer   hexBuf)
220     {
221 
222         // Check if there is enough buffer space to dump 16 bytes
223 
224         int dumplen = byt.length - off;
225         if (dumplen > 16)
226             dumplen = 16;
227 
228         // Dump a 16 byte block of data
229 
230         for (int i = 0; i < dumplen; i++)
231         {
232 
233             // Get the current byte
234 
235             int curbyt = (int) (byt[off++] & 0x00FF);
236 
237             // Output the hex string
238 
239             hexBuf.append(Integer.toHexString((curbyt & 0xF0) >> 4));
240             hexBuf.append(Integer.toHexString(curbyt & 0x0F));
241             hexBuf.append(" ");
242 
243             // Output the character equivalent, if printable
244 
245             if (Character.isLetterOrDigit((char) curbyt) || Character.getType((char) curbyt) != Character.CONTROL)
246                 ascBuf.append((char) curbyt);
247             else
248                 ascBuf.append(".");
249         }
250 
251         // Output the hex dump line
252 
253         hexBuf.append("  - ");
254 
255         // Return the new data offset
256 
257         return off;
258     }
259 }
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