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.

Answer 1

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

Answer 2

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.

Answer 3

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?

Answer 4

On Gili's request: https://jsr311.dev.java.net/nonav/releases/1.0/javax/ws/rs/core/UriBuilder.html is what worked for Gili (also because he is already using JAX-RS).

Answer 5

Hello. 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 at least download the reference implementation (jersey).

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