encodeURIComponent and decodeURIComponent in Java

A very common task when working with Webservices, is to encode/decode specific URI components, and for there is no direct API in Java for the same, it gets a difficult. Below is the code piece that I have been using for quite some time now.

public static final String ALLOWED_CHARS = "abcdefghijklmnopqrstuvwxyz"+

"ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_.!~*'()";
 
 public static String encodeURIComponent(String input) {
  if(StringUtils.isEmpty(input)) {
   return input;
  }
   
  int l = input.length();
  StringBuilder o = new StringBuilder(l * 3);
  try {
   for (int i = 0; i < l; i++) {
    String e = input.substring(i, i + 1);
    if (ALLOWED_CHARS.indexOf(e) == -1) {
     byte[] b = e.getBytes("utf-8");
     o.append(getHex(b));
     continue;
    }
    o.append(e);
   }
   return o.toString();
  } catch(UnsupportedEncodingException e) {
   e.printStackTrace();
  }
  return input;
 }
  
 private static String getHex(byte buf[]) {
  StringBuilder o = new StringBuilder(buf.length * 3);
  for (int i = 0; i < buf.length; i++) {
   int n = (int) buf[i] & 0xff;
   o.append("%");
   if (n < 0x10) {
    o.append("0");
   }
   o.append(Long.toString(n, 16).toUpperCase());
  }
  return o.toString();
 }
 
 public static String decodeURIComponent(String encodedURI) {
  char actualChar;
 
  StringBuffer buffer = new StringBuffer();
 
  int bytePattern, sumb = 0;
 
  for (int i = 0, more = -1; i < encodedURI.length(); i++) {
   actualChar = encodedURI.charAt(i);
 
   switch (actualChar) {
    case '%': {
     actualChar = encodedURI.charAt(++i);
     int hb = (Character.isDigit(actualChar) ? actualChar - '0'
       : 10 + Character.toLowerCase(actualChar) - 'a') & 0xF;
     actualChar = encodedURI.charAt(++i);
     int lb = (Character.isDigit(actualChar) ? actualChar - '0'
       : 10 + Character.toLowerCase(actualChar) - 'a') & 0xF;
     bytePattern = (hb << 4) | lb;
     break;
    }
    case '+': {
     bytePattern = ' ';
     break;
    }
    default: {
     bytePattern = actualChar;
    }
   }
 
   if ((bytePattern & 0xc0) == 0x80) { // 10xxxxxx
    sumb = (sumb << 6) | (bytePattern & 0x3f);
    if (--more == 0)
     buffer.append((char) sumb);
   } else if ((bytePattern & 0x80) == 0x00) { // 0xxxxxxx
    buffer.append((char) bytePattern);
   } else if ((bytePattern & 0xe0) == 0xc0) { // 110xxxxx
    sumb = bytePattern & 0x1f;
    more = 1;
   } else if ((bytePattern & 0xf0) == 0xe0) { // 1110xxxx
    sumb = bytePattern & 0x0f;
    more = 2;
   } else if ((bytePattern & 0xf8) == 0xf0) { // 11110xxx
    sumb = bytePattern & 0x07;
    more = 3;
   } else if ((bytePattern & 0xfc) == 0xf8) { // 111110xx
    sumb = bytePattern & 0x03;
    more = 4;
   } else { // 1111110x
    sumb = bytePattern & 0x01;
    more = 5;
   }
  }
  return buffer.toString();
 }