org.kontalk.util.EncodingUtils.java Source code

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Here is the source code for org.kontalk.util.EncodingUtils.java

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/*
 * Kontalk Java client
 * Copyright (C) 2014 Kontalk Devteam <devteam@kontalk.org>
    
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
    
 * 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 for more details.
    
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.kontalk.util;

import java.util.EnumSet;
import java.util.Map;
import org.json.simple.JSONObject;

public final class EncodingUtils {

    private static final char[] HEX_ARRAY = "0123456789ABCDEF".toCharArray();

    private EncodingUtils() {
        throw new AssertionError();
    }

    public static String bytesToHex(byte[] bytes) {
        char[] hexChars = new char[bytes.length * 2];
        int v;
        for (int j = 0; j < bytes.length; j++) {
            v = bytes[j] & 0xFF;
            hexChars[j * 2] = HEX_ARRAY[v >>> 4];
            hexChars[j * 2 + 1] = HEX_ARRAY[v & 0x0F];
        }
        return new String(hexChars);
    }

    /**
     * Get an enum set by parsing an integer which represents a bit array.
     * Source: http://stackoverflow.com/questions/2199399/storing-enumset-in-a-database
     * @param <T> type of elements in enum set
     * @param enumClass enum class to determine the type
     * @param decoded integer decoded as
     * @return an enum set containing the enums specified by the integer
     */
    public static <T extends Enum<T>> EnumSet<T> intToEnumSet(Class<T> enumClass, int decoded) {
        EnumSet<T> enumSet = EnumSet.noneOf(enumClass);
        T[] enums = enumClass.getEnumConstants();
        while (decoded != 0) {
            int ordinal = Integer.numberOfTrailingZeros(decoded);
            enumSet.add(enums[ordinal]);
            decoded -= Integer.lowestOneBit(decoded);
        }
        return enumSet;
    }

    /**
     * Encode an enum set to an integer representing a bit array.
     */
    public static int enumSetToInt(EnumSet<?> enumSet) {
        int b = 0;
        for (Object o : enumSet) {
            b += 1 << ((Enum) o).ordinal();
        }
        return b;
    }

    // using legacy lib, raw types extend Object
    @SuppressWarnings("unchecked")
    public static void putJSON(JSONObject json, String key, String value) {
        if (!value.isEmpty())
            json.put(key, value);
    }

    public static String getJSON(Map<?, ?> map, String key) {
        String value = (String) map.get(key);
        return value == null ? "" : value;
    }
}