Java Hex Calculate toHexEscape(final int u0)

Description

to Hex Escape

License

Open Source License

Declaration

private static String toHexEscape(final int u0) 

Method Source Code

//package com.java2s;
/*/*  w  w  w .jav a 2 s. c o  m*/
 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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 in the LICENSE file that
 * accompanied this code).
 *
 * 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

public class Main {
    private static String toHexEscape(final int u0) {
        int u = u0;
        int len;
        final byte[] b = new byte[6];

        if (u <= 0x7f) {
            b[0] = (byte) u;
            len = 1;
        } else {
            // > 0x7ff -> length 2
            // > 0xffff -> length 3
            // and so on. each new length is an additional 5 bits from the
            // original 11
            // the final mask is 8-len zeros in the low part.
            len = 2;
            for (int mask = u >>> 11; mask != 0; mask >>>= 5) {
                len++;
            }
            for (int i = len - 1; i > 0; i--) {
                b[i] = (byte) (0x80 | (u & 0x3f));
                u >>>= 6; // 64 bits per octet.
            }

            b[0] = (byte) (~((1 << (8 - len)) - 1) | u);
        }

        final StringBuilder sb = new StringBuilder();
        for (int i = 0; i < len; i++) {
            sb.append('%');
            if ((b[i] & 0xff) < 0x10) {
                sb.append('0');
            }
            sb.append(Integer.toHexString(b[i] & 0xff).toUpperCase());
        }

        return sb.toString();
    }
}

Related

1. toHexDigits(byte[] bytes)
2. toHexDigits(int value)
3. toHexDump(byte[] ab, int cBytesPerLine)
4. toHexDump(byte[] buffer, int offset, int length, boolean hex, boolean ascii)
5. toHexDump(byte[] bytes)
6. toHexFilter(String inAscii)
7. toHexFromBin(final String binSymbols)
8. toHexFromByte(byte b)
9. toHexFromByte(final byte b)