java.io.EOFException: No content to map to Object due to end of input

Server Side

@RequestMapping (value="url",method=RequestMethod.GET)
public @ResponseBody String sampleMethod (@RequestBody String json){

     ObjectMapper mapper = new ObjectMapper();
     HashMap<Object, Object> params = new HashMap<Object,Object>();
     params = mapper.readValue(json, new TypeReference<Map<String,Object>>() { });
 

     return "";
}

Client Side

jQuery(document).ready(function(){

var datas =  {id:"id",password:"password"};

jQuery.ajax({
       type: "POST",
       url: 'http://localhost:8080/url',
       data: JSON.stringify(datas),
       contentType: "application/json; charset=utf-8",
       dataType: "json",
       success: function (result){
        if (result.status != 0){
            return;
        }
       },
       error: function (){
        alert ("Error");
       }
});
});

Result : java.io.EOFException: No content to map to Object due to end of input

symptom : method=RequestMethod.GET change to POST