Java String Unescape unescape(String s)

Description

unescape

License

Open Source License

Declaration

public static String unescape(String s) 

Method Source Code

//package com.java2s;

public class Main {
    public static String unescape(String s) {
        StringBuffer sbuf = new StringBuffer();
        int l = s.length();
        int ch = -1;
        int b, sumb = 0;
        for (int i = 0, more = -1; i < l; i++) {
            /* Get next byte b from URL segment s */
            switch (ch = s.charAt(i)) {
            case '%':
                ch = s.charAt(++i);// w w  w  . j a  va  2 s.  c  om
                int hb = (Character.isDigit((char) ch) ? ch - '0' : 10 + Character.toLowerCase((char) ch) - 'a')
                        & 0xF;
                ch = s.charAt(++i);
                int lb = (Character.isDigit((char) ch) ? ch - '0' : 10 + Character.toLowerCase((char) ch) - 'a')
                        & 0xF;
                b = (hb << 4) | lb;
                break;
            case '+':
                b = ' ';
                break;
            default:
                b = ch;
            }
            /* Decode byte b as UTF-8, sumb collects incomplete chars */
            if ((b & 0xc0) == 0x80) { // 10xxxxxx (continuation byte)
                sumb = (sumb << 6) | (b & 0x3f); // Add 6 bits to sumb
                if (--more == 0)
                    sbuf.append((char) sumb); // Add char to sbuf
            } else if ((b & 0x80) == 0x00) { // 0xxxxxxx (yields 7 bits)
                sbuf.append((char) b); // Store in sbuf
            } else if ((b & 0xe0) == 0xc0) { // 110xxxxx (yields 5 bits)
                sumb = b & 0x1f;
                more = 1; // Expect 1 more byte
            } else if ((b & 0xf0) == 0xe0) { // 1110xxxx (yields 4 bits)
                sumb = b & 0x0f;
                more = 2; // Expect 2 more bytes
            } else if ((b & 0xf8) == 0xf0) { // 11110xxx (yields 3 bits)
                sumb = b & 0x07;
                more = 3; // Expect 3 more bytes
            } else if ((b & 0xfc) == 0xf8) { // 111110xx (yields 2 bits)
                sumb = b & 0x03;
                more = 4; // Expect 4 more bytes
            } else /*if ((b & 0xfe) == 0xfc)*/ { // 1111110x (yields 1 bit)
                sumb = b & 0x01;
                more = 5; // Expect 5 more bytes
            }
            /* We don't test if the UTF-8 encoding is well-formed */
        }
        return sbuf.toString();
    }
}

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