UriUtils does double encode [SPR-8507]

[spring-projects-issues]

Eduard Dudar opened SPR-8507 and commented

I'm seeing quite strange behavior and I'm not sure why UriUtils works this way.

In detail I'm having URL that I want to ask using RestTemplate. Url is the following [CODE]API=http://server/path?key=...&url={url}[/CODE] where {url} is variable that is passed from the outside. Url that is passed in can be any valid URL with query string or not. Then I call [CODE]this.rest.getForObject(API, String.class, url)[/CODE] that call API mentioned above and passed incoming URL into.

And here is what I see. When I pass unencoded url into REST call UriUtils does nothing so I get more parameters then I need because own url parameters are just appended to API parameters. When I do manual encoding first I get double encoded parameter that is also invalid.

I found the code and it definitely works that way, but I'm not sure why already encoded parameters are forced to be double encoded.

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Affects: 3.0.5

Reference URL: http://forum.springsource.org/showthread.php?111473-UriUtils-does-double-encode

Issue Links:

• UriTemplate doesn't encode query parameters [SPR-8403] #13050 UriTemplate doesn't encode query parameters

[spring-projects-issues]

Chris Beams commented

Rossen - this looks at least loosely related to #13050.

[spring-projects-issues]

Rossen Stoyanchev commented

There is a good reason for this behavior.

When the RestTemplate is invoked using one of the methods accepting a String URI template, the characters '&', '=', and '+' are not encoded since they are legal URI characters. It wouldn't be possible to know which ones should be encoded and which ones shouldn't.

Consider the following where the value of "url" is "url=http://host/path?a=b&b=c":

http://server/path?key=foo&{url}

As for the double encoding, the javadoc of the RestTemplate is very clear that the URI template is expected to not be encoded or else it will be double-encoded.

You can use the RestTemplate methods that accept a URI instead. See the recommendation here:
https://jira.springsource.org/browse/SPR-5516?focusedCommentId=58444&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-58444

You can also watch or comment under #13050 for a potential improvement.