Question

I am looking to parse a URL to obtain a collection of the querystring parameters in Java. To be clear, I need to parse a given URL(or string value of a URL object), not the URL from a servlet request.

It looks as if the javax.servlet.http.HttpUtils.parseQueryString method would be the obvious choice, but it has been deprecated.

Is there an alternative method that I am missing, or has it just been deprecated without an equivalent replacement/enhanced function?

Answer 1

Well, as you mention that the URL does not come from a servlet request, the right answer is, as usual, it depends.

The problem with query part of an url is that there is no clear specification about how to handle parameters duplication.

For example, consider an url like this one:

http://www.example.com?param1=value1&param2=value2&param1=value3 

What do you expect as a value for param1? the first value, the last one, an array? The issue is that, according to the specs, all these answers are valid and server vendor are free to support one of these or another. Some use the param1[] notation to indicate that it has to be treated as an array, but again, this is not a unified solution.

So the ‘best’ solution is to know how your destination handle parameters, and mimic the behaviour with a self-made utility class.