CODEWITHSUNDEEP
javajavascriptspringjakarta-eespring-mvc
Ankur Jain
Ankur Jain

Reputation: 1404

Springs MVC JSON Response and convert it to JS Object

I am having a question that how can I send JSON Object from Springs MVC so that I can convert it into a JavaScript Object on my HTML Page.

In a traditional way I do it: Below is a snippet from Java Servlet which sets a request attribute and forward it to the JSP Page.

   JSONObject jsonObj = new JSONObject();
   jsonObj.put("name","test");
   jsonObj.put("age",24);
   request.setAttribute("jsonObj",jsonObj);
   request.getRequestDispatcher("test.jsp").forward(request,response);

In JSP I retrieve as :

   <script type="text/javascript">
    var jsonObj =<%=request.getAttribute("jsonObj"); %>;
    alert("name = "+jsonObj.name+" ; age = "+jsonObj.age); // This will output name and age from the JSON Object
   </script>

So what I need to ask how can I do the same in Springs MVC. How can I send the JSONObject from Dispatcher Servlet, and convert it to JS object in my JSP page ?

Upvotes: 2

Views: 11539

Answers (4)

Gunjan Shah
Gunjan Shah

Reputation: 5168

As per your requirement, I suggest you to use AJAX call with JSON as data type.

For example :

$.ajax({
                    url: "getFormatIdDescMap?compId="+compId,
                    global: false,
                    type: "POST",
                    dataType:"json",
                    contanttype:'text/json',
                    async:false,
                    error:function(){
                        alert("Error during retrieving the foramt ID List");
                    },
                    success: function(data){                                                
                        //REMOVE ALL THE OLD VALUES OF FORMAT DROP DOWN
                        removeDropDownVals('formatList');

                        var optn;
                        for(var index=0;index<data.formatKeys.length;index++){
                            optn = document.createElement("option");
                            document.getElementById("formatList").options.add(optn);
                            optn.text =data.formatDescs[index];
                            optn.value=data.formatKeys[index];  
                        }
                    }
                });

            });

In the code above, I am preparing a new list of Formats based on company ID. You can iterate over the response.

It will give response text as per your requirements. But here note that .. if you are getting json Array in the response, it will contain that data in square bracket like..[1,2,3] and If you are getting response in JSON Object then it will be displayed in curly braces like {"data",[1,2,3]}.

Upvotes: 0

jinchuan
jinchuan

Reputation: 21

I think you should use ajax(for example jquery),the following is spring mvc

@RequestMapping(value = "/admin/new/list", method = RequestMethod.GET)
@ResponseBody
public List<News> list()
{
  return newsDao.findAll();
}

and in the jsp page,you may use ajax util (for example jquery)

$.ajax({
            type: "GET",
            url: '<c:url value="/admin/new/list"/>',
            cache:false,
            dataType :'json',
            success: function(data){
                 alert(data);               
           }
    });

the data is json object I don't know whether the above is what you need

Upvotes: 2

David
David

Reputation: 20063

A much easier way to do this is to include the Jackson dependencies in maven and use @ResponseBody to return a JSON representation of the object, without having to manually write the manipulation.

Have a look at the example below, you shouldn't have to write any tranlation to JSON code.

http://www.mkyong.com/spring-mvc/spring-3-mvc-and-json-example/

Upvotes: 0

derlinuxer
derlinuxer

Reputation: 574

An easy way to do this using the ObjectMapper. It will create an JSON String from your Object. And that you can send to your view/jsp.

I put an small example of a controller I do this (just snipped).

@Controller
public class UsersSettingsController {

    @Autowired
    UserSettingsDefaultService userSettingsService;


    @RequestMapping(value="/userSettings/dynamic/userSettings", method=RequestMethod.GET)
    public ModelAndView get() throws Exception {
        ModelAndView mav = new ModelAndView();
        ObjectMapper mapper = new ObjectMapper();


    User user = (User)SecurityContextHolder.getContext().getAuthentication().getPrincipal();
    UserSettings userSet = userSettingsService.getUserSettingsByUser(user);

    mav.addObject("userSettingsJSON", mapper.writeValueAsString(userSet));

    mav.setViewName("userSettings/dynamic/filter");


        return mav;
    }
}

Or course can you create your JSON Object in your Contoller step by step like you did in your example. Then you don't need the Mapper, just sending the String to your View.

In the JSP you load the json String like this into a JS var:

var jsonString = '${userSettingsJSON}';

To get elements from JSON String or parse, see: http://www.json.org/js.html.
I'm an KnockOut Framework Fan would do it with it.

Upvotes: 4

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