This is working code for a URI template (RFC 6570) implementation; when the character to render is not within a specific character set, it is needed to grab the UTF-8 representation of that character and encode each byte as a percent-encoded sequence.

The question is whether something more efficient than this exists?

private static String encodeChar(final char c)
    final String tmp = new String(new char[] { c });
    final byte[] bytes = tmp.getBytes(Charset.forName("UTF-8"));
    final StringBuilder sb = new StringBuilder();
    for (final byte b: bytes)
        sb.append('%').append(UnsignedBytes.toString(b, 16));
    return sb.toString();

Note: UnsignedBytes.toString() is from Guava.

  • \$\begingroup\$ What kind of performance do you need? Is this just a general question? Did you try essentially the same thing on the whole string and see if it was faster? \$\endgroup\$ – Quentin Pradet May 24 '13 at 12:32
  • \$\begingroup\$ Doing it on a whole string is a no-no. Only the characters out of a specified character set need to be percent-encoded this way. What I am asking is whether a better way to achieve such an encoding of a single character exists. For reference, see RFC 6570, section 1.5. \$\endgroup\$ – fge May 24 '13 at 21:09
  • \$\begingroup\$ Of course, on a whole string it would skip most characters - I don't know how easy it would be with getBytes. (You didn't answer my first two questions.) \$\endgroup\$ – Quentin Pradet May 26 '13 at 11:33
  • \$\begingroup\$ It is not a question of performance; the problem is that I think the code is a little clumsy as it stands. In this sense it is more of a general question. The main encoding function uses a CharMatcher to determine whether the current character in a string should be percent encoded or not. \$\endgroup\$ – fge May 26 '13 at 11:38

Documentation here

public static void main(final String[] args) {
        try {
        } catch (final UnsupportedEncodingException e) {
            System.out.println("BIG PB");

Output :


You have the same for URLEDecoder


Found in src of iMeMex Dataspace ManagementSystem

public static URI encode(String uriStr) throws URISyntaxException {
    if (uriStr != null) {
        // poor man's encoding
        uriStr = uriStr.replaceAll(" ", "%20");
    return new URI(uriStr);

JavaDoc here

But URI from Java does not change other %VALUES.

| improve this answer | |
  • 1
    \$\begingroup\$ This does not fit the bill. For instance, it replaces spaces with '+', and the encoded character list differs from what URI Template requires. \$\endgroup\$ – fge May 24 '13 at 7:24

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