How do I encode URI parameter values?

Question

I want to send a URI as the value of a query/matrix parameter. Before I can append it to an existing URI, I need to encode it according to RFC 2396. For example, given the input:

http://google.com/resource?key=value1 & value2

I expect the output:

http%3a%2f%2fgoogle.com%2fresource%3fkey%3dvalue1%2520%26%2520value2

Neither java.net.URLEncoder nor java.net.URI will generate the right output. URLEncoder is meant for HTML form encoding which is not the same as RFC 2396. URI has no mechanism for encoding a single value at a time so it has no way of knowing that value1 and value2 are part of the same key.

I am not sure I understand what result do you expect. I would use URLEncoder. — Peter Štibraný, Jan 14 '09 at 18:26
According to the Javadoc for URL: "The URLEncoder and URLDecoder classes can also be used, but only for HTML form encoding, which is not the same as the encoding scheme defined in RFC2396." — Gili, Jan 14 '09 at 18:30
@Peter: Agreed, but the latter is dead. There is at least one up-voted answer so it won't show up in the list of unanswered questions even though the answer is technically wrong. If you want to help please go vote it down to zero. — Gili, Jan 14 '09 at 18:41
I wonder what would be result for example you give in your question. — Peter Štibraný, Jan 14 '09 at 18:41
Sorry, I removed my comment about this being a duplicate of http://stackoverflow.com/questions/304806/encode-and-decode-rfc2396-urls — Peter Štibraný, Jan 14 '09 at 18:43
Bugger, Stackoverflow marks a question as answered even if all answers have a score of zero! Please consider voting for http://stackoverflow.uservoice.com/pages/general/suggestions/103614-use-score-0-instead-of-up-votes-for-unanswered-questions to fix this. — Gili, Jan 14 '09 at 19:07
related http://stackoverflow.com/questions/724043/http-url-address-encoding-in-java — Adriano, Jul 17 '13 at 14:33
Is this like this question: [How to encode URL parameters?](http://stackoverflow.com/questions/8135132/how-to-encode-url-parameters) , except for Java (that one is for JavaScript) ? If yes, java.net.URLEncoder is the (or "a") correct answer. — David Balažic, Aug 18 '15 at 11:41
@DavidBalažic Wrong, I explicitly mention why `URLEncoder` won't work in the above question. — Gili, Aug 18 '15 at 15:21

score 31 · Accepted Answer · edited Nov 07 '11 at 16:26

31

Jersey's UriBuilder encodes URI components using application/x-www-form-urlencoded and RFC 3986 as needed. According to the Javadoc

Builder methods perform contextual encoding of characters not permitted in the corresponding URI component following the rules of the application/x-www-form-urlencoded media type for query parameters and RFC 3986 for all other components. Note that only characters not permitted in a particular component are subject to encoding so, e.g., a path supplied to one of the path methods may contain matrix parameters or multiple path segments since the separators are legal characters and will not be encoded. Percent encoded values are also recognized where allowed and will not be double encoded.

edited Nov 07 '11 at 16:26

Gili

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answered Jan 14 '09 at 20:39

Peter Štibraný

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URL is unreachable. But http://download.oracle.com/javaee/6/api/javax/ws/rs/core/UriBuilder.html is available already – sergtk Dec 24 '10 at 15:59
@sergdev, fixed the link. Thanks for the head's up! – Gili Jan 19 '11 at 17:35
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How exactly did you produce the expected output mentioned above using the UriBuilder? I have no clue how to tell it to encode the part before the "?". Thanks! – tbk May 24 '11 at 15:38
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If you are not use JAX-RS and are using Spring you could use Spring's UriUtils – Adam Gent Jul 16 '11 at 03:51
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@tbh, The point I was trying to make is that if you use UriBuilder it'll encode what needs to be encoded for you. If you want to manually encode sections of text it turns out that http://stackoverflow.com/questions/304806/encode-and-decode-rfc2396-urls/579167#579167 will work. Alternatively, you can use UriBuilder.fromPath("http://host/").matrixParam("key", "http://google.com/resource?key=value1 & value2").build() and you'll get back "http://host/;key=http:%2F%2Fgoogle.com%2Fresource%3Fkey%3Dvalue1%20&%20value2". – Gili Nov 07 '11 at 16:22
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Beware of using UriBuilder for "free" URLs that do not use JAX-RS's parameter scheme with curly braces. Even if it might be an exotic value, try this: `UriBuilder.fromPath("http://www.query.example/").queryParam("key", "{val}").build();` will fail. `"http://www.query.example?key=" + URLEncoder.encode("{val}", "UTF-8")` will work. – ujay68 Sep 10 '15 at 19:28
@ujay68: UriBuilder treats curly brace as template delimiters. Have you tried `UriBuilder.fromPath("http://www.query.example/").queryParam("key", "{val}").build("{val}")`? – Julien Carsique Oct 29 '15 at 17:22
FYI. If you have a full URL string already, and just care about special characters being replaces appropriately, you can simply just build it like so: UriBuilder.fromPath(urlString).build(); That will encode all the special characters to the right of the first "/" at the end of the hostname of the URL. – AdeelMufti May 09 '16 at 16:20

score 20 · Answer 2 · answered Jul 16 '11 at 03:48

20

You could also use Spring's UriUtils

answered Jul 16 '11 at 03:48

Adam Gent

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score 9 · Answer 3 · edited Apr 12 '18 at 03:08

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I don't have enough reputation to comment on answers, but I just wanted to note that downloading the JSR-311 api by itself will not work. You need to download the reference implementation (jersey).

Only downloading the api from the JSR page will give you a ClassNotFoundException when the api tries to look for an implementation at runtime.

edited Apr 12 '18 at 03:08

App Dev Guy

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answered Dec 30 '09 at 22:05

yincrash

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specifically, you need jsr311-api, jersey-server, and jersey-core jars. – yincrash Dec 30 '09 at 22:43

Daniel Murphy · Answer 4 · 2011-03-31T02:48:09.297

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I wrote my own, it's short, super simple, and you can copy it if you like: http://www.dmurph.com/2011/01/java-uri-encoder/

edited Mar 31 '11 at 02:48

answered Jan 17 '11 at 06:15

Daniel Murphy

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I guess people are hesitant to like this solution because maybe they fear it will have bugs etc. It looks pretty comprehensive, and has had a couple of bugs addressed already, so I think I will try it out. Java and Objective C both don't have built in routines to do this kind of encoding, which is just ... baffling – Herr Grumps Oct 10 '12 at 07:54
Hmm, this is for the URI itself and not for the parameters? – Somatik Dec 11 '12 at 10:15
Spaces should be escaped :) It will only include numbers, letters, and the 'mark' characters as unescaped – Daniel Murphy May 07 '13 at 20:38
@HerrGrumps What? Obj-C has def had built-in URL encoding for a long time. – Jadar Jan 31 '17 at 05:55
@Jadar oh? ok, maybe I was wrong on Obj-C and/or Java not having it - sorry :) For reference maybe you can post a reply with some class/method names in the event that it might help someone out who might not know where to look (like me ;) ) – Herr Grumps Jan 31 '17 at 10:37
@HerrGrumps Not sure about pure Java, I ended up using Android specific classes. On iOS you can use the `URLComponents` class to break a URL down into its constituent parts and the `queryItems` property to set parameters. But that's outside the scope of this answer and question. ;) – Jadar Feb 01 '17 at 03:00

score 2 · Answer 5 · answered Jan 14 '09 at 19:30

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It seems that CharEscapers from Google GData-java-client has what you want. It has uriPathEscaper method, uriQueryStringEscaper, and generic uriEscaper. (All return Escaper object which does actual escaping). Apache License.

answered Jan 14 '09 at 19:30

Peter Štibraný

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Unfortunately it uses some other classes and interfaces, but I think you'll be able to modify it to suit your needs. – Peter Štibraný Jan 14 '09 at 19:37
"There has to be an easier way than this". It amazes me that this common use-case (building URIs) isn't easier to do. java.net.URI should do a better job. – Gili Jan 14 '09 at 19:43
I was surprised at how messy this area is (honestly, I didn't even know there is such thing as special URI Encoding ... I learned something). – Peter Štibraný Jan 14 '09 at 19:44
Peter, I just realized this might work: https://jsr311.dev.java.net/nonav/releases/1.0/javax/ws/rs/core/UriBuilder.html I am using JAX-RS anyway for my application. I'll try it and report back. – Gili Jan 14 '09 at 20:05
Peter, please add the following and I will mark it as the accepted answer: " javax.ws.rs.core.UriBuilder will do what you want: https://jsr311.dev.java.net/nonav/releases/1.0/javax/ws/rs/core/UriBuilder.html " – Gili Jan 14 '09 at 20:11
Feel free to answer your question yourself :-) You found solution which works best for you. People who are searching for same problem can then choose whatever works for them. – Peter Štibraný Jan 14 '09 at 20:14
The reason I want you to post the answer is that I can't "accept" my own answer. Please post a new answer and I'll "accept it". – Gili Jan 14 '09 at 20:21
OK. Didn't know about accepting own answer, I thought it's possible. – Peter Štibraný Jan 14 '09 at 20:40
+1 for CharEscapers. I ran into this issue today and this fixed it: // false will force spaces to encode as %20 CharEscapers.uriEscaper(false).escape(value); – James Cooper Dec 12 '09 at 00:13

score -2 · Answer 6 · answered Jan 14 '09 at 18:33

-2

I think that the URI class is the one that you are looking for.

answered Jan 14 '09 at 18:33

Glenn

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It doesn't help because it expects me to pass in a full query string. It has no way of knowing which part of the string needs to be encoded and which part does not. I need a method that takes in a raw parameter value and passes out the URL encoded form. – Gili Jan 14 '09 at 18:37
Yes. Stackoverflow marks questions as answered if they have been up-voted once. This answer has been up-voted by one person and I down-voted it. It still marks my questions as answered last time I checked. – Gili Jan 14 '09 at 19:30
My bad. You're right. I assumed "upvoted answer" meant ... you know, an answer with a positive number to its left ... – A. Rex Jan 14 '09 at 19:32
Same here, please vote for http://stackoverflow.uservoice.com/pages/general/suggestions/103614-use-score-0-instead-of-up-votes-for-unanswered-questions – Gili Jan 14 '09 at 19:35
Why don't you update your question to indicate that the URI class will not work for you? Otherwise, someone else will enter in the same advice even if I delete my answer. BTW, why can't the full URI be encoded? – Glenn Jan 14 '09 at 19:57
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I will update the question. The reason the full URI can't be encoded is if I pass in "key=value with spaces&still part of value" the constructor has no way of knowing where the value begins and ends. – Gili Jan 14 '09 at 20:09

score -2 · Answer 7 · edited Jun 20 '20 at 09:12

-2

Mmhh I know you've already discarded URLEncoder, but despite of what the docs say, I decided to give it a try.

You said:

For example, given an input:

http://google.com/resource?key=value

I expect the output:

http%3a%2f%2fgoogle.com%2fresource%3fkey%3dvalue

So:

C:\oreyes\samples\java\URL>type URLEncodeSample.java
import java.net.*;

public class URLEncodeSample {
    public static void main( String [] args ) throws Throwable {
        System.out.println( URLEncoder.encode( args[0], "UTF-8" ));
    }
}

C:\oreyes\samples\java\URL>javac URLEncodeSample.java

C:\oreyes\samples\java\URL>java URLEncodeSample "http://google.com/resource?key=value"
http%3A%2F%2Fgoogle.com%2Fresource%3Fkey%3Dvalue

As expected.

What would be the problem with this?

edited Jun 20 '20 at 09:12

Community

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answered Jan 14 '09 at 19:44

OscarRyz

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It is similar to RFC2396 but is not the same. For example, try encoding spaces. URLEncoder will encode it as '+', URIs expect %20 instead. There are other differences. – Gili Jan 14 '09 at 19:49
Ok but you wouldn't be encodgin: "value with space" but "value+with+space" like this: – OscarRyz Jan 14 '09 at 20:05
like:java URLEncodeSample "http://google.com/resource?key=value+with+spaces" http%3A%2F%2Fgoogle.com%2Fresource%3Fkey%3Dvalue%2Bwith%2Bspaces – OscarRyz Jan 14 '09 at 20:09
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There are a whole slew of rules that one must follow for RFC 2369. Instead of playing games with the input string I'd rather find a class that encodes things properly. – Gili Jan 14 '09 at 20:20
What do you intend to do? That would be very helpful to know in order to give you the right answer. – OscarRyz Jan 14 '09 at 20:35

How do I encode URI parameter values?

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