UrlEncoder.java

/*
 * Copyright © 2012 Nokia Corporation. All rights reserved.
 * Nokia and Nokia Connecting People are registered trademarks of Nokia Corporation.
 * Oracle and Java are trademarks or registered trademarks of Oracle and/or its
 * affiliates. Other product and company names mentioned herein may be trademarks
 * or trade names of their respective owners.
 * See LICENSE.TXT for license information.
 */
package com.nokia.example.attractions.utils;

public final class UrlEncoder {

    /**
     * This method is used to encode the URL String
     *
     * @param s
     * @return the encoded URL string
     */
    public static String encode(String s) {
        StringBuffer sbuf = new StringBuffer();
        int len = s.length();
        for (int i = 0; i < len; i++) {
            int ch = s.charAt(i);
            if ('A' <= ch && ch <= 'Z') {  // 'A'..'Z'
                sbuf.append((char) ch);
            }
            else if ('a' <= ch && ch <= 'z') {  // 'a'..'z'
                sbuf.append((char) ch);
            }
            else if ('0' <= ch && ch <= '9') {  // '0'..'9'
                sbuf.append((char) ch);
            }
            else if (ch == ' ') { // space
                sbuf.append('+');
            }
            else if (ch == '-' || ch == '_' // don't need encoding
                || ch == '.' || ch == '*') {
                sbuf.append((char) ch);
            }
            else if (ch <= 0x007f) {  // other ASCII
                sbuf.append(hex(ch));
            }
            else if (ch <= 0x07FF) {  // non-ASCII <= 0x7FF
                sbuf.append(hex(0xc0 | (ch >> 6)));
                sbuf.append(hex(0x80 | (ch & 0x3F)));
            }
            else {  // 0x7FF < ch <= 0xFFFF
                sbuf.append(hex(0xe0 | (ch >> 12)));
                sbuf.append(hex(0x80 | ((ch >> 6) & 0x3F)));
                sbuf.append(hex(0x80 | (ch & 0x3F)));
            }
        }
        return sbuf.toString();
    }

    /**
     * Get the encoded value of a single symbol, each return value is 3 characters long
     *
     * @param sym
     * @return the encoded value
     */
    private static String hex(int sym) {
        return (HEX.substring(sym * 3, sym * 3 + 3));
    }
    // Hex constants concatenated into a string, messy but efficient
    private final static String HEX =
        "%00%01%02%03%04%05%06%07%08%09%0a%0b%0c%0d%0e%0f%10%11%12%13%14%15%16%17%18%19%1a%1b%1c%1d%1e%1f"
        + "%20%21%22%23%24%25%26%27%28%29%2a%2b%2c%2d%2e%2f%30%31%32%33%34%35%36%37%38%39%3a%3b%3c%3d%3e%3f"
        + "%40%41%42%43%44%45%46%47%48%49%4a%4b%4c%4d%4e%4f%50%51%52%53%54%55%56%57%58%59%5a%5b%5c%5d%5e%5f"
        + "%60%61%62%63%64%65%66%67%68%69%6a%6b%6c%6d%6e%6f%70%71%72%73%74%75%76%77%78%79%7a%7b%7c%7d%7e%7f"
        + "%80%81%82%83%84%85%86%87%88%89%8a%8b%8c%8d%8e%8f%90%91%92%93%94%95%96%97%98%99%9a%9b%9c%9d%9e%9f"
        + "%a0%a1%a2%a3%a4%a5%a6%a7%a8%a9%aa%ab%ac%ad%ae%af%b0%b1%b2%b3%b4%b5%b6%b7%b8%b9%ba%bb%bc%bd%be%bf"
        + "%c0%c1%c2%c3%c4%c5%c6%c7%c8%c9%ca%cb%cc%cd%ce%cf%d0%d1%d2%d3%d4%d5%d6%d7%d8%d9%da%db%dc%dd%de%df"
        + "%e0%e1%e2%e3%e4%e5%e6%e7%e8%e9%ea%eb%ec%ed%ee%ef%f0%f1%f2%f3%f4%f5%f6%f7%f8%f9%fa%fb%fc%fd%fe%ff";
}