Java - URL Encoder

public class URLEncoder {
  public static String encode(String s) {
    ByteArrayOutputStream bOut = new ByteArrayOutputStream();
    DataOutputStream dOut = new DataOutputStream(bOut);
    StringBuffer ret = new StringBuffer(); //return value
    try {
      dOut.writeUTF(s);
    } catch (IOException ex) {
      ex.printStackTrace();
    }
    ByteArrayInputStream bIn = new ByteArrayInputStream(bOut.toByteArray());
    bIn.read();
    bIn.read();
    int c = bIn.read();
    while (c >= 0) {
      if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') || c == '.' || c == '-' || c == '*' || c == '_') {
        ret.append((char) c);
      } else if (c == ' ') {
        ret.append('+');
      } else {
        if (c < 128) {
          appendHex(c, ret);
        } else if (c < 224) {
          appendHex(c, ret);
          appendHex(bIn.read(), ret);
        } else if (c < 240) {
          appendHex(c, ret);
          appendHex(bIn.read(), ret);
          appendHex(bIn.read(), ret);
        }
      }
      c = bIn.read();
    }
    return ret.toString();
  }

  private static void appendHex(int arg0, StringBuffer buff) {
    buff.append('%');
    if (arg0 < 16) {
      buff.append('0');
    }
    buff.append(Integer.toHexString(arg0));
  }
}