Spring/Rest @PathVariable character encoding

Question

In the environment I'm using (Tomcat 6), percent sequences in path segments apparently are decoded using ISO-8859-1 when being mapped to a @PathVariable.

I'd like that to be UTF-8.

I already configured Tomcat to use UTF-8 (using the URIEncoding attribute in server.xml).

Is Spring/Rest doing the decoding on its own? If yes, where can I override the default encoding?

Additional information; here's my test code:

@RequestMapping( value = "/enc/{foo}", method = RequestMethod.GET )
public HttpEntity<String> enc( @PathVariable( "foo" ) String foo, HttpServletRequest req )
{
  String resp;

  resp = "      path variable foo: " + foo + "\n" + 
         "      req.getPathInfo(): " + req.getPathInfo() + "\n" +
         "req.getPathTranslated(): " + req.getPathTranslated() + "\n" + 
         "    req.getRequestURI(): " + req.getRequestURI() + "\n" + 
         "   req.getContextPath(): " + req.getContextPath() + "\n";

  HttpHeaders headers = new HttpHeaders();
  headers.setContentType( new MediaType( "text", "plain", Charset.forName( "UTF-8" ) ) );
  return new HttpEntity<String>( resp, headers );
}

If I do an HTTP GET request with the following URI path:

/TEST/enc/%c2%a3%20and%20%e2%82%ac%20rates

which is the UTF-8 encoded then percent-encoded form of

/TEST/enc/£ and € rates

the output that I get is:

      path variable foo: £ and ⬠rates
      req.getPathInfo(): /enc/£ and € rates
req.getPathTranslated(): C:\Users\jre\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\TEST\enc\£ and € rates
    req.getRequestURI(): /TEST/enc/%C2%A3%20and%20%E2%82%AC%20rates
   req.getContextPath(): /TEST

which to me shows that Tomcat (after setting the URIEncoding attribute) does the right thing (see getPathInfo()), but the path variable is decoded still in ISO-8859-1.

And the answer is:

Spring/Rest apparently uses the request encoding, which is a very strange thing to do, as this is about the body, not the URI. Sigh.

Adding this:

<filter>
  <filter-name>CharacterEncodingFilter</filter-name>
  <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
  <init-param>
      <param-name>encoding</param-name>
      <param-value>UTF-8</param-value>
  </init-param>
</filter>
<filter-mapping>
  <filter-name>CharacterEncodingFilter</filter-name>
  <url-pattern>/*</url-pattern>
</filter-mapping>

fixed the problem. It really should be simpler.

And actually, it's worse:

If the method indeed has a request body, and that one isn't encoded in UTF-8, the additional forceEncoding parameter is needed. This seems to work, but I'm concerned it will cause more problems later on.

Another approach

In the meantime, I found out that it's possible to disable the decoding, my specifying

<property name="urlDecode" value="false"/>

...in which case the recipient can to the right thing; but of course this will make lots of other things harder.

Answer 1

I thing that you need add filter to web.xml

<filter>
    <filter-name>CharacterEncodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
        <param-name>encoding</param-name>
        <param-value>UTF-8</param-value>
    </init-param>
    <init-param>
        <param-name>forceEncoding</param-name>
        <param-value>true</param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>CharacterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

Answer 2

The path variable is still decoded in ISO-8859-1 for me, even with the Character Encoding Filter. Here is what I had to do to get around this. Please let me know if you have any other ideas!

To see the actual UTF-8 decoded characters on the server, you can just do this and take a look at the value (you need to add "HttpServletRequest httpServletRequest" to your controller parameters):

String requestURI = httpServletRequest.getRequestURI();
String decodedURI = URLDecoder.decode(requestURI, "UTF-8");

I can then do whatever I want (like get the parameter manually from the decoded URI), now that I have the right decoded data on the server.

Answer 3

Try to configure connector on Tomcat in server.xml. Add useBodyEncodingForURI="true" or URIEncoding="UTF-8" to your Connector tag. For example:

    <Connector port="8080" protocol="HTTP/1.1"
           connectionTimeout="20000"
           useBodyEncodingForURI="true"
           redirectPort="8443" />

Answer 4

But doesn't it suck that you have to mess with the Tomcat configuration (URIEncoding) at all to make this work? If the servlet API provided a way to obtain the path and request parameters in their undecoded representation, the application (or Spring) could deal with the decoding entirely on its own. And apparently, HttpServletRequest#getPathInfo and HttpServletRequest#getQueryString would even provide this, but for the latter this would mean that Spring would have to parse and decode the query string itself and not rely on HttpServletRequest#getParameter and friends. Apparently they don't do this, which means you can't have @RequestParam or @PathVariable capture anything other than us-ascii strings safely without relying on the servlet container's configuration.