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Commons IO example source code file (HexDump.java)

This example Commons IO source code file (HexDump.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons IO tags/keywords

a, arrayindexoutofboundsexception, arrayindexoutofboundsexception, c, e, eol, hexdump, hexdump, illegalargumentexception, illegalargumentexception, io, ioexception, string, stringbuilder, stringbuilder

The Commons IO HexDump.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.io;

import java.io.IOException;
import java.io.OutputStream;

/**
 * Dumps data in hexadecimal format.
 * <p>
 * Provides a single function to take an array of bytes and display it
 * in hexadecimal form.
 * <p>
 * Origin of code: POI.
 *
 * @author Scott Sanders
 * @author Marc Johnson
 * @version $Id: HexDump.java 736507 2009-01-22 00:52:15Z jukka $
 */
public class HexDump {

    /**
     * Instances should NOT be constructed in standard programming.
     */
    public HexDump() {
        super();
    }

    /**
     * Dump an array of bytes to an OutputStream. The output is formatted
     * for human inspection, with a hexadecimal offset followed by the
     * hexadecimal values of the next 16 bytes of data and the printable ASCII
     * characters (if any) that those bytes represent printed per each line
     * of output.
     * <p>
     * The offset argument specifies the start offset of the data array
     * within a larger entity like a file or an incoming stream. For example,
     * if the data array contains the third kibibyte of a file, then the
     * offset argument should be set to 2048. The offset value printed
     * at the beginning of each line indicates where in that larger entity
     * the first byte on that line is located.
     * <p>
     * All bytes between the given index (inclusive) and the end of the
     * data array are dumped. 
     *
     * @param data  the byte array to be dumped
     * @param offset  offset of the byte array within a larger entity
     * @param stream  the OutputStream to which the data is to be
     *               written
     * @param index initial index into the byte array
     *
     * @throws IOException is thrown if anything goes wrong writing
     *         the data to stream
     * @throws ArrayIndexOutOfBoundsException if the index is
     *         outside the data array's bounds
     * @throws IllegalArgumentException if the output stream is null
     */

    public static void dump(byte[] data, long offset,
                            OutputStream stream, int index)
            throws IOException, ArrayIndexOutOfBoundsException,
            IllegalArgumentException {
        
        if ((index < 0) || (index >= data.length)) {
            throw new ArrayIndexOutOfBoundsException(
                    "illegal index: " + index + " into array of length "
                    + data.length);
        }
        if (stream == null) {
            throw new IllegalArgumentException("cannot write to nullstream");
        }
        long display_offset = offset + index;
        StringBuilder buffer = new StringBuilder(74);

        for (int j = index; j < data.length; j += 16) {
            int chars_read = data.length - j;

            if (chars_read > 16) {
                chars_read = 16;
            }
            dump(buffer, display_offset).append(' ');
            for (int k = 0; k < 16; k++) {
                if (k < chars_read) {
                    dump(buffer, data[k + j]);
                } else {
                    buffer.append("  ");
                }
                buffer.append(' ');
            }
            for (int k = 0; k < chars_read; k++) {
                if ((data[k + j] >= ' ') && (data[k + j] < 127)) {
                    buffer.append((char) data[k + j]);
                } else {
                    buffer.append('.');
                }
            }
            buffer.append(EOL);
            stream.write(buffer.toString().getBytes());
            stream.flush();
            buffer.setLength(0);
            display_offset += chars_read;
        }
    }

    /**
     * The line-separator (initializes to "line.separator" system property.
     */
    public static final String EOL =
            System.getProperty("line.separator");
    private static final char[] _hexcodes =
            {
                '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
                'A', 'B', 'C', 'D', 'E', 'F'
            };
    private static final int[] _shifts =
            {
                28, 24, 20, 16, 12, 8, 4, 0
            };

    /**
     * Dump a long value into a StringBuilder.
     *
     * @param _lbuffer the StringBuilder to dump the value in
     * @param value  the long value to be dumped
     * @return StringBuilder containing the dumped value.
     */
    private static StringBuilder dump(StringBuilder _lbuffer, long value) {
        for (int j = 0; j < 8; j++) {
            _lbuffer
                    .append(_hexcodes[((int) (value >> _shifts[j])) & 15]);
        }
        return _lbuffer;
    }

    /**
     * Dump a byte value into a StringBuilder.
     *
     * @param _cbuffer the StringBuilder to dump the value in
     * @param value  the byte value to be dumped
     * @return StringBuilder containing the dumped value.
     */
    private static StringBuilder dump(StringBuilder _cbuffer, byte value) {
        for (int j = 0; j < 2; j++) {
            _cbuffer.append(_hexcodes[(value >> _shifts[j + 6]) & 15]);
        }
        return _cbuffer;
    }

}

Other Commons IO examples (source code examples)

Here is a short list of links related to this Commons IO HexDump.java source code file:



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