使用Spring可以使路径变量可选吗？

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或/json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

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();
}

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"
    }       
}

还不知道您是否还可以使用@PathVariable批注注入路径变量的Map。我不确定此功能是否在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();
    }
}

您可以使用：

@RequestParam(value="somvalue",required=false)

用于可选参数而不是pathVariable

Spring 5 / Spring Boot 2示例：

阻塞

@GetMapping({"/dto-blocking/{type}", "/dto-blocking"})
public ResponseEntity<Dto> getDtoBlocking(
        @PathVariable(name = "type", required = false) String type) {
    if (StringUtils.isEmpty(type)) {
        type = "default";
    }
    return ResponseEntity.ok().body(dtoBlockingRepo.findByType(type));
}

反应性

@GetMapping({"/dto-reactive/{type}", "/dto-reactive"})
public Mono<ResponseEntity<Dto>> getDtoReactive(
        @PathVariable(name = "type", required = false) String type) {
    if (StringUtils.isEmpty(type)) {
        type = "default";
    }
    return dtoReactiveRepo.findByType(type).map(dto -> ResponseEntity.ok().body(dto));
}

Nicolai Ehmann的注释和wildloop的答案的简化示例（适用于Spring 4.3.3+），基本上，您required = false现在可以使用：

  @RequestMapping(value = {"/json/{type}", "/json" }, method = RequestMethod.GET)
  public @ResponseBody TestBean testAjax(@PathVariable(required = false) String type) {
    if (type != null) {
      // ...
    }
    return new TestBean();
  }

选中此Spring 3 WebMVC-可选路径变量。它显示了对AntPathMatcher进行扩展以启用可选路径变量的文章，可能会有帮助。塞巴斯蒂安·赫罗德（Sebastian Herold）的所有发表文章。

$.ajax({
            type : 'GET',
            url : '${pageContext.request.contextPath}/order/lastOrder',
            data : {partyId : partyId, orderId :orderId},
            success : function(data, textStatus, jqXHR) });

@RequestMapping(value = "/lastOrder", method=RequestMethod.GET)
public @ResponseBody OrderBean lastOrderDetail(@RequestParam(value="partyId") Long partyId,@RequestParam(value="orderId",required=false) Long orderId,Model m ) {}