/**
  * 业务功能:请求和某人交换名片
  *
  * @param self_id 自己的名片
  * @param other_id 要交换的人的名片
  * @return
  */
 @RequestMapping("{self_id}/request/{other_id}")
 @ResponseBody
 public ResponseEntity<Map<String, Object>> requestExchangeCard(
     @PathVariable String self_id, @PathVariable String other_id) {
   return new ResponseEntity<Map<String, Object>>(
       cardService.createRequest(self_id, other_id), HttpStatus.OK);
 }