使用Spring，我可以创建一个可选的路径变量吗？

Question

在Spring 3.0中，我可以有一个可选的path变量吗？例如@RequestMapping(value = "/json/{type}", method = RequestMethod.GET)public @ResponseBody TestBean testAjax(        HttpServletRequest req,        @PathVariable String type,        @RequestParam("track") String track) {    return new TestBean();}在这里我想/json/abc还是/json要调用相同的方法。一种明显的解决方法是声明type为请求参数：@RequestMapping(value = "/json", method = RequestMethod.GET)public @ResponseBody TestBean testAjax(        HttpServletRequest req,        @RequestParam(value = "type", required = false) String type,        @RequestParam("track") String track) {    return new TestBean();}然后/json?type=abc&track=aa或/json?track=rr将工作

Answer 1

您不能具有可选的路径变量，但是可以有两个调用相同服务代码的控制器方法：

@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();

}

Answer 2

如果您在使用Spring 4.1和Java 8，你可以使用java.util.Optional它支持@RequestParam，@PathVariable，@RequestHeader和@MatrixVariableSpring MVC中-

@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"

    }       

}

Answer 3

众所周知，您还可以使用@PathVariable批注注入路径变量的Map。我不确定该功能是否在Spring 3.0中可用或是否在以后添加，但是这是解决示例的另一种方法：

@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();

    }

}