hexdumpencoder.java

来自「This is a resource based on j2me embedde」· Java 代码 · 共 124 行

/*
 * @(#)HexDumpEncoder.java	1.18 06/10/10
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.  
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER  
 *   
 * This program is free software; you can redistribute it and/or  
 * modify it under the terms of the GNU General Public License version  
 * 2 only, as published by the Free Software Foundation.   
 *   
 * This program is distributed in the hope that it will be useful, but  
 * WITHOUT ANY WARRANTY; without even the implied warranty of  
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU  
 * General Public License version 2 for more details (a copy is  
 * included at /legal/license.txt).   
 *   
 * You should have received a copy of the GNU General Public License  
 * version 2 along with this work; if not, write to the Free Software  
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  
 * 02110-1301 USA   
 *   
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa  
 * Clara, CA 95054 or visit www.sun.com if you need additional  
 * information or have any questions. 
 *
 */


package sun.misc;
import java.io.PrintStream;
import java.io.OutputStream;
import java.io.IOException;

/**
 * This class encodes a buffer into the classic: "Hexadecimal Dump" format of
 * the past. It is useful for analyzing the contents of binary buffers.
 * The format produced is as follows:
 * <pre>
 * xxxx: 00 11 22 33 44 55 66 77   88 99 aa bb cc dd ee ff ................
 * </pre>
 * Where xxxx is the offset into the buffer in 16 byte chunks, followed
 * by ascii coded hexadecimal bytes followed by the ASCII representation of
 * the bytes or '.' if they are not valid bytes.
 *
 * @version	1.12, 02/02/00
 * @author	Chuck McManis
 */

public class HexDumpEncoder extends CharacterEncoder {

    private int offset;
    private int thisLineLength;
    private int currentByte;
    private byte thisLine[] = new byte[16];

    static void hexDigit(PrintStream p, byte x) {
	char c;

	c = (char) ((x >> 4) & 0xf);
	if (c > 9)
	    c = (char) ((c-10) + 'A');
	else
	    c = (char)(c + '0');
	p.write(c);
	c = (char) (x & 0xf);
	if (c > 9)
	    c = (char)((c-10) + 'A');
	else
	    c = (char)(c + '0');
	p.write(c);
    }

    protected int bytesPerAtom() {
	return (1);
    }

    protected int bytesPerLine() {
	return (16);
    }

    protected void encodeBufferPrefix(OutputStream o) throws IOException {
	offset = 0;
	super.encodeBufferPrefix(o);
    }

    protected void encodeLinePrefix(OutputStream o, int len) throws IOException {
	hexDigit(pStream, (byte)((offset >>> 8) & 0xff));
	hexDigit(pStream, (byte)(offset & 0xff));
	pStream.print(": ");
	currentByte = 0;
	thisLineLength = len;
    }
	
    protected void encodeAtom(OutputStream o, byte buf[], int off, int len) throws IOException {
	thisLine[currentByte] = buf[off];
	hexDigit(pStream, buf[off]);
	pStream.print(" ");
	currentByte++;
	if (currentByte == 8)
	    pStream.print("  ");
    }

    protected void encodeLineSuffix(OutputStream o) throws IOException {
	if (thisLineLength < 16) {
	    for (int i = thisLineLength; i < 16; i++) {
		pStream.print("   ");
		if (i == 7)
		    pStream.print("  ");
	    }
	}
	pStream.print(" ");
	for (int i = 0; i < thisLineLength; i++) {
	    if ((thisLine[i] < ' ') || (thisLine[i] > 'z')) {
		pStream.print(".");
	    } else {
		pStream.write(thisLine[i]);
            }
	}
	pStream.println();
	offset += thisLineLength;
    }

}