Question

我目前正在从我创建的REST服务中读取数据。返回的数据为<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <label class="col-sm-2 control-label" for="radioo">Commission type <b style="color:red;">*</b></label> <div class="col-lg-10" required> <label class="custom-control custom-control-primary custom-radio"> <input class="custom-control-input" type="radio" name="comission_type" value="0" checked="checked"> <span class="custom-control-indicator"></span> <span class="custom-control-label">Fixed price</span> </label> <label class="custom-control custom-control-primary custom-radio"> <input class="custom-control-input" type="radio" name="comission_type" value="1"> <span class="custom-control-indicator"></span> <span class="custom-control-label">Percentage wise</span> </label> <label class="custom-control custom-control-primary custom-radio"> <input class="custom-control-input" type="radio" name="comission_type" value="2"> <span class="custom-control-indicator"></span> <span class="custom-control-label">Monthly</span> </label> <label class="custom-control custom-control-primary custom-radio"> <input class="custom-control-input" type="radio" name="comission_type" value="3"> <span class="custom-control-indicator"></span> <span class="custom-control-label">Yearly</span> </label> </div> <form name="fixedForm"> <div id="fixPerDiv" style="display:block;"> <div class="form-group"> <div class="col-lg-11 col-lg-offset-1"> <div class="table-responsive"> <table class="table" id='commision_tbl'> <tr> <td width='20%'>Start price</td> <td width='20%'>End price</td> <td width='20%'>Start date</td> <td width='20%'>End date</td> <td width='20%'>Comission</td> <td> </td> </tr> <tr> <td> <input type="number" name="commissions_start_price[]" class="form-control" value="" placeholder="Start Price" required="required" /> </td> <td> <input type="number" name="commissions_end_price[]" class="form-control" value="" placeholder="End Price" required="required" /> </td> <td> <div class="input-with-icon"> <input type="text" data-provide="datepicker" value="" data-date-today-highlight="true" name="start_date[]" class="form-control" placeholder="Start date" required="required" /><span class="icon icon-calendar input-icon"></span></div> </td> <td> <div class="input-with-icon"> <input type="text" data-provide="datepicker" value="" data-date-today-highlight="true" name="end_date[]" class="form-control" placeholder="End date" required="required" /><span class="icon icon-calendar input-icon"></span></div> </td> <td> <input type="number" name="commissions_amount[]" class="form-control" value="" placeholder="Commision price" required="required" /> </td> <td> </td> </tr> <tr> <td colspan="6" align="center"> <input type="button" value="Add More" id="price_addmorebtn" class="btn btn-outline-info"> </td> </tr> </table> </div> </div> </div> </div> </form> <form name="monYearForm"> <div id="monYearDiv" style="display:none;"> <div class="form-group"> <div class="col-lg-11 col-lg-offset-1"> <div class="table-responsive"> <table class="table" id='commision_tb2'> <tr> <td width='30%'>Start date</td> <td width='30%'>End date</td> <td width='30%'>Comission</td> <td> </td> </tr> <tr> <td> <div class="input-with-icon"> <input type="text" data-provide="datepicker" data-date-today-highlight="true" name="start_date[]" class="form-control" placeholder="Start date" required="required" /><span class="icon icon-calendar input-icon"></span></div> </td> <td> <div class="input-with-icon"> <input type="text" data-provide="datepicker" data-date-today-highlight="true" name="end_date[]" class="form-control" placeholder="End date" required="required" /><span class="icon icon-calendar input-icon"></span></div> </td> <td> <input type="number" name="commissions_amount[]" class="form-control" placeholder="Commision price" required="required" /> </td> <td> </td> </tr> <tr> <td colspan="4" align="center"> <input type="button" value="Add More" id="price_addmore" class="btn btn-outline-info"> </td> </tr> </table> </div> </div> </div> </div> </form>。列表中填充了YAML文件内容，这些内容被提取到地图中，然后提取到列表中。

当get调用返回一些内容（即List对象中的内容）时，我的代码完美无缺。当没有返回任何内容时，我得到一个java.net.UnknownServiceException：没有内容类型

List用于填充HTML选择器。如果没有返回任何内容，则不会出现任何选择器。我目前通过捕获异常并继续AJAX调用来完成此工作，如下所示。我只是想知道是否有更好的方法（比如检查返回的InputStream中是否有内容）。

List<String>

编辑：我觉得我的错误可能源于当get方法找不到索引时地图对象返回的内容。所以这里通常是我的REST服务正在做的事情（注意URL请求中给出变量“role”）：

URL url = new URL("myurl");
HttpURLConnection request = (HttpURLConnection) url.openconnection();
request.connect();

try{
   //parse
   JsonParser jp = new.JsonParser();
   JsonElement root = jp.parse(new InputStreamReader((InputStream) request.getContent()));
   JsonArray unsanitizedMembers = root.getAsJsonArray();

   //remove quotes from input
   List<String> members = new ArrayList<String>();
   for(int i=0; i<unsanitizedMembers.size(); i++)
      members.add(unsanitizedMembers.get(i).getAsString());

   //add to thymeleaf model
   model.addAttributes("members", members);
}
catch(UnknownServiceException e){
   //return nothing if given list is empty
   return "fragments :: memberResults";
}
return "fragments :: memberResults";

Answer 1

检查内容是否为null。也许是这样的：

if (request.getContent() != null)
    JsonElement root = jp.parse(new InputStreamReader((InputStream) request.getContent()));

如何判断是否没有要从HttpURLConnection中读取的内容

1 个答案: