Encoding and decoding tools

 

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;

import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.binary.Base64;
import org.apache.commons.codec.binary.Hex;
import org.apache.commons.lang.StringEscapeUtils;

/**
 * Encapsulates encoding and decoding tool classes of various formats.
 *
 * 1. Hex/base64 encoding of Commons-Codec
 * 2.Commons-Lang for xml / html escape
 * 3.URLEncoder provided by JDK
 *
 */
public abstract class EncodeUtils {

    private static final String ALPHABET = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
    private static final String DEFAULT_URL_ENCODING = "UTF-8";

    /**
     * Hex encoding, byte[]->String.
     */
    public static String encodeHex(byte[] input) {
        return Hex.encodeHexString(input);
    }

    /**
     * Hex decoding, String->byte[].
     */
    public static byte[] decodeHex(String input) {
        try {
            return Hex.decodeHex(input.toCharArray());
        } catch (DecoderException e) {
            throw new IllegalStateException("Hex Decoder exception", e);
        }
    }

    /**
     * Base64 encoding, byte[]->String.
     */
    public static String encodeBase64(byte[] input) {
        return Base64.encodeBase64String(input);
    }

    /**
     * Base64 encoded, URL safe (converts illegal characters '+' and '/' in Base64 URLs to '-' and '_', see RFC3548).
     */
    public static String encodeUrlSafeBase64(byte[] input) {
        return Base64.encodeBase64URLSafeString(input);
    }

    /**
     * Base64 decoding, String->byte[].
     */
    public static byte[] decodeBase64(String input) {
        return Base64.decodeBase64(input);
    }

    /**
     * Base62(0_9A_Za_z) encoded numbers, long->String.
     */
    public static String encodeBase62(long num) {
        return alphabetEncode(num, 62);
    }

    /**
     * Base62(0_9A_Za_z) decode number, String->long.
     */
    public static long decodeBase62(String str) {
        return alphabetDecode(str, 62);
    }

    private static String alphabetEncode(long num, int base) {
        num = Math.abs(num);
        StringBuilder sb = new StringBuilder();
        for (; num > 0; num /= base) {
            sb.append(ALPHABET.charAt((int) (num % base)));
        }

        return sb.toString();
    }

    private static long alphabetDecode(String str, int base) {
        AssertUtils.hasText(str);

        long result = 0;
        for (int i = 0; i < str.length(); i++) {
            result += ALPHABET.indexOf(str.charAt(i)) * Math.pow(base, i);
        }

        return result;
    }

    /**
     * URL encoding, Encode defaults to UTF-8.
     */
    public static String urlEncode(String part) {
        try {
            return URLEncoder.encode(part, DEFAULT_URL_ENCODING);
        } catch (UnsupportedEncodingException e) {
            throw ExceptionUtils.unchecked(e);
        }
    }

    /**
     * URL decoding, Encode defaults to UTF-8.
     */
    public static String urlDecode(String part) {

        try {
            return URLDecoder.decode(part, DEFAULT_URL_ENCODING);
        } catch (UnsupportedEncodingException e) {
            throw ExceptionUtils.unchecked(e);
        }
    }

    /**
     * Html transcoding.
     */
    public static String htmlEscape(String html) {
        return StringEscapeUtils.escapeHtml(html);
    }

    /**
     * Html decoding.
     */
    public static String htmlUnescape(String htmlEscaped) {
        return StringEscapeUtils.unescapeHtml(htmlEscaped);
    }

    /**
     * Xml transcoding.
     */
    public static String xmlEscape(String xml) {
        return StringEscapeUtils.escapeXml(xml);
    }

    /**
     * Xml decoding.
     */
    public static String xmlUnescape(String xmlEscaped) {
        return StringEscapeUtils.unescapeXml(xmlEscaped);
    }
}