Yet another blog

 
 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) ; 
        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() ; 
}