With Spring can I make an optional path variable?

You can't have optional path variables, but you can have two controller methods which call the same service code:

@RequestMapping(value = "/json/{type}", method = RequestMethod.GET)public @ResponseBody TestBean typedTestBean(        HttpServletRequest req,        @PathVariable String type,        @RequestParam("track") String track) {    return getTestBean(type);}@RequestMapping(value = "/json", method = RequestMethod.GET)public @ResponseBody TestBean testBean(        HttpServletRequest req,        @RequestParam("track") String track) {    return getTestBean();}

If you are using Spring 4.1 and Java 8 you can use java.util.Optional which is supported in @RequestParam, @PathVariable, @RequestHeader and @MatrixVariable in Spring MVC -

@RequestMapping(value = {"/json/{type}", "/json" }, method = RequestMethod.GET)public @ResponseBody TestBean typedTestBean(    @PathVariable Optional<String> type,    @RequestParam("track") String track) {          if (type.isPresent()) {        //type.get() will return type value        //corresponds to path "/json/{type}"    } else {        //corresponds to path "/json"    }       }

It's not well known that you can also inject a Map of the path variables using the @PathVariable annotation. I'm not sure if this feature is available in Spring 3.0 or if it was added later, but here is another way to solve the example:

@RequestMapping(value={ "/json/{type}", "/json" }, method=RequestMethod.GET)public @ResponseBody TestBean typedTestBean(    @PathVariable Map<String, String> pathVariables,    @RequestParam("track") String track) {    if (pathVariables.containsKey("type")) {        return new TestBean(pathVariables.get("type"));    } else {        return new TestBean();    }}