Java Equivalent to JavaScript's Encodeuricomponent That Produces Identical Output

Java equivalent to JavaScript's encodeURIComponent that produces identical output?

Looking at the implementation differences, I see that:

MDC on encodeURIComponent():

• literal characters (regex representation): [-a-zA-Z0-9._*~'()!]

Java 1.5.0 documentation on URLEncoder:

• literal characters (regex representation): [-a-zA-Z0-9._*]
• the space character " " is converted into a plus sign "+".

So basically, to get the desired result, use URLEncoder.encode(s, "UTF-8") and then do some post-processing:

• replace all occurrences of "+" with "%20"
• replace all occurrences of "%xx" representing any of [~'()!] back to their literal counter-parts

JS encodeURI Equivalent of Java

URLEncoder is for encoding form data. To create an escaped URL or URI, use the java.net.URI class:

URI uri = new URI("file", "///10.10.10.10/Yev Pri - Ru─▒n G├╢z├╝yle Ortado─Яu.pdf", null);
String escapedURI = uri.toASCIIString();

Note: You cannot use new URI("file://///10.10.10.10/Yev Pri - Ru─▒n G├╢z├╝yle Ortado─Яu.pdf") because that constructor does not perform percent-escaping of characters which may not legally appear directly in URIs. The class documentation explicitly specifies that the one-argument constructor expects the argument to already have proper escaping.

How to get Java to match JavaScript encodeURIComponent() method?

According to Mozilla Developer Docs encodeURICompoent() uses UTF-8 to encode. When I run this on your string I get tester%C3%A6%C3%B8%C3%A5 as expected. When i run the following Java code:

System.out.println(URLEncoder.encode("testeræøå", "UTF-8"));

It also prints tester%C3%A6%C3%B8%C3%A5. I also ran your test and got:

    ------ START TESTING WITH USER ID = 'dummy' ----------------------
Test URLEncoder.encode(userId): dummy
Test URLEncoder.encode(userId,"UTF-8"): dummy
Test URLEncoder.encode(userId,"UTF-16"): dummy
Test URLEncoder.encode(userId,"UTF-16LE"): dummy
Test URLEncoder.encode(userId,"UTF-16BE"): dummy
Test engine.eval("encodeURIComponent(\""+userId+"\")"): dummy
Test encodeURIComponent(userId): dummy
TEST new URI(userId).toASCIIString(): dummy
------ END TESTING WITH USER ID = 'dummy' ----------------------

------ START TESTING WITH USER ID = 'testeræøå' ----------------------
Test URLEncoder.encode(userId): tester%C3%A6%C3%B8%C3%A5
Test URLEncoder.encode(userId,"UTF-8"): tester%C3%A6%C3%B8%C3%A5
Test URLEncoder.encode(userId,"UTF-16"): tester%FE%FF%00%E6%00%F8%00%E5
Test URLEncoder.encode(userId,"UTF-16LE"): tester%E6%00%F8%00%E5%00
Test URLEncoder.encode(userId,"UTF-16BE"): tester%00%E6%00%F8%00%E5
Test engine.eval("encodeURIComponent(\""+userId+"\")"): tester%C3%A6%C3%B8%C3%A5
Test encodeURIComponent(userId): tester%C3%A6%C3%B8%C3%A5
TEST new URI(userId).toASCIIString(): tester%C3%A6%C3%B8%C3%A5
------ END TESTING WITH USER ID = 'testeræøå' ----------------------

------ START TESTING WITH USER ID = 'tester%C3%A6%C3%B8%C3%A5' ----------------------
Test URLEncoder.encode(userId): tester%25C3%25A6%25C3%25B8%25C3%25A5
Test URLEncoder.encode(userId,"UTF-8"): tester%25C3%25A6%25C3%25B8%25C3%25A5
Test URLEncoder.encode(userId,"UTF-16"): tester%FE%FF%00%25C3%FE%FF%00%25A6%FE%FF%00%25C3%FE%FF%00%25B8%FE%FF%00%25C3%FE%FF%00%25A5
Test URLEncoder.encode(userId,"UTF-16LE"): tester%25%00C3%25%00A6%25%00C3%25%00B8%25%00C3%25%00A5
Test URLEncoder.encode(userId,"UTF-16BE"): tester%00%25C3%00%25A6%00%25C3%00%25B8%00%25C3%00%25A5
Test engine.eval("encodeURIComponent(\""+userId+"\")"): tester%25C3%25A6%25C3%25B8%25C3%25A5
Test encodeURIComponent(userId): tester%25C3%25A6%25C3%25B8%25C3%25A5
TEST new URI(userId).toASCIIString(): tester%C3%A6%C3%B8%C3%A5
------ END TESTING WITH USER ID = 'tester%C3%A6%C3%B8%C3%A5' ----------------------

This is what I would expect.

I think you need to check the file encoding for your Java source file. If you are using Eclipse it defaults to cp1252 for some reason. The first thing I do when I install Eclipse is change the default encoding to UTF-8.

Decode url which has been encoded in javascript

Use java.net.URLDecoder.

But pay attention that there are several differences between java and javascript implementations.

For details take a look on:

Difference in URL decode/encode UTF-8 between Java and JS/AS3 (bug!?)

Java equivalent to JavaScript's encodeURIComponent that produces identical output?

Java URL encoding: URLEncoder vs. URI

Although I think the answer from @fge is the right one, as I was using a 3rd party webservice that relied on the encoding outlined in the W3Schools article, I followed the answer from Java equivalent to JavaScript's encodeURIComponent that produces identical output?

public static String encodeURIComponent(String s) {
    String result;

    try {
        result = URLEncoder.encode(s, "UTF-8")
                .replaceAll("\\+", "%20")
                .replaceAll("\\%21", "!")
                .replaceAll("\\%27", "'")
                .replaceAll("\\%28", "(")
                .replaceAll("\\%29", ")")
                .replaceAll("\\%7E", "~");
    } catch (UnsupportedEncodingException e) {
        result = s;
    }

    return result;
}

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