Easyui the error handling returned by the service side when the form submits the interaction with SPRINGMVC

The error callback function is not available in the submit interface of the Asyui form, and a solution on the web is to concatenate. Success (function () {}). Error (function () {}) and then unified processing through JQXHR But I have found that this scenario calls the. Error (), regardless of whether the server returns a correct or an exception, and it is a bit confusing to write code. After two days of groping, basically found the answer.
in the front Easyui the form submission can handle a successful callback by checking the data = = ' of Success ', while $.ajax commit specifies the error callback function.
The approximate code is as follows:
$.ajax ({
    url:url,// Corresponding controller returns httpstatus.nocontent, error throws exception
    type: ' Post ',
    Data:data,
    Success:function (res) {},//successfully processed
    error:function (err) {}//error handling
});
$ (' #fm '). Form ({
    url:url,//corresponding controller returns httpstatus.success, error throws exception
    SUCCESS: Function (res) {
        if (res = = ') {
           //successfully processed
&nbs P      }else{//error handling
       }
   },
    ' JSON '
});

Easyui form submits error handling returned by the server when interacting with SPRINGMVC