title: spring pathvariable doesn't work ,can't get the value
body: <p>when i enter:<a href="http://localhost:8080/sys_manager/admin/sys/resource/update/1009" rel="nofollow">http://localhost:8080/sys_manager/admin/sys/resource/update/1009</a>
  it's can enter into this method,but the id value is null,:</p>
  
  <pre class="lang-java prettyprint-override"><code>    @RequestMapping(value = "update/{id}", method = RequestMethod.GET)
      public String showUpdateForm(@PathVariable("id") ID id, Model model) {
          M m = baseService.findOne(id);
          if (permissionList != null) {
              this.permissionList.assertHasUpdatePermission();
          }
          setCommonData(model);
          model.addAttribute(Constants.OP_NAME, "修改");
          model.addAttribute("m", m);
          return viewName("editForm");
      }
  </code></pre>
  
  <p>One picture more than thousands of words,here is the snapshot:<a href="https://plus.google.com/photos/109577783306525329699/albums/6135767537581420673" rel="nofollow">https://plus.google.com/photos/109577783306525329699/albums/6135767537581420673</a></p>