Returning JSON response from Servlet to Javascript JSP page

Question

I think  actually I KNOW   I m doing something wrong here I am trying to populate some values into HashMap and add each hasmap to a list which will be added to a JSON object   JSONObject json   new JSONObject    try       Map address      List addresses   new ArrayList         int count   15       for  int i 0   i lt count   i                  address   new HashMap            address put  CustomerName         Decepticons    i           address put  AccountId            1999    i           address put  SiteId               1888    i           address put  Number                7    i           address put  Building              StarScream Skyscraper    i           address put  Street                Devestator Avenue    i           address put  City                  Megatron City    i           address put  ZipCode              ZZ00 XX1    i           address put  Country               CyberTron    i           addresses add address             json put  Addresses   addresses     catch  JSONException jse       response setContentType  application json    response getWriter   write json toString       My problem is I know this is returning a string  which I cannot seem to parse  which is the problem   My question is how do I return the actual JSON encoded string  or even should I be doing this   or what is the best method of attack for this type of problem  The JavaScript I am using for this is below   function getReadyStateHandler req           Return an anonymous function that listens to the        XMLHttpRequest instance     return function                     If the request s status is  complete          if  req readyState    4                           Check that a successful server response was received             if  req status    200                                msgBox  JSON Response recieved                       populateDatagrid req responseText toJSON                               else                                  An HTTP problem has occurred                 alert  HTTP error      req status                                     Note the JSON Response comes back fine  but its a string  Any advice is greatly appreciated  I am also opening to using googles Gson  but don t have too much knowledge on that

User · Answer

I used JSONObject as shown below in Servlet.

    JSONObject jsonReturn = new JSONObject();

    NhAdminTree = AdminTasks.GetNeighborhoodTreeForNhAdministrator( connection, bwcon, userName);

    map = new HashMap<String, String>();
    map.put("Status", "Success");
    map.put("FailureReason", "None");
    map.put("DataElements", "2");

    jsonReturn = new JSONObject();
    jsonReturn.accumulate("Header", map);

    List<String> list = new ArrayList<String>();
    list.add(NhAdminTree);
    list.add(userName);

    jsonReturn.accumulate("Elements", list);

The Servlet returns this JSON object as shown below:

    response.setContentType("application/json");
    response.getWriter().write(jsonReturn.toString());

This Servlet is called from Browser using AngularJs as below

$scope.GetNeighborhoodTreeUsingPost = function(){
    alert("Clicked GetNeighborhoodTreeUsingPost : " + $scope.userName );

    $http({

        method: 'POST',
        url : 'http://localhost:8080/EPortal/xlEPortalService',
        headers: {
           'Content-Type': 'application/json'
         },
        data : {
            'action': 64,
            'userName' : $scope.userName
        }
    }).success(function(data, status, headers, config){
        alert("DATA.header.status : " + data.Header.Status);
        alert("DATA.header.FailureReason : " + data.Header.FailureReason);
        alert("DATA.header.DataElements : " + data.Header.DataElements);
        alert("DATA.elements : " + data.Elements);

    }).error(function(data, status, headers, config) {
        alert(data + " : " + status + " : " + headers + " : " + config);
    });

};

This code worked and it is showing correct data in alert dialog box:

Data.header.status : Success

Data.header.FailureReason : None

Data.header.DetailElements : 2

Data.Elements : Coma seperated string values i.e. NhAdminTree, userName

User · Answer

Got it working  I should have been building a JSONArray of JSONObjects and then add the array to a final  Addresses  JSONObject  Observe the following   JSONObject json        new JSONObject    JSONArray  addresses   new JSONArray    JSONObject address  try      int count   15      for  int i 0   i lt count   i                address   new JSONObject           address put  CustomerName         Decepticons    i          address put  AccountId            1999    i          address put  SiteId               1888    i          address put  Number                7    i          address put  Building              StarScream Skyscraper    i          address put  Street                Devestator Avenue    i          address put  City                  Megatron City    i          address put  ZipCode              ZZ00 XX1    i          address put  Country               CyberTron    i          addresses add address           json put  Addresses   addresses     catch  JSONException jse        response setContentType  application json    response getWriter   write json toString       This worked and returned valid and parse-able JSON  Hopefully this helps someone else in the future  Thanks for your help Marcel

User · Answer

I think that what you want to do is turn the JSON string back into an object when it arrives back in your XMLHttpRequest - correct   If so  you need to eval the string to turn it into a JavaScript object - note that this can be unsafe as you re trusting that the JSON string isn t malicious and therefore executing it  Preferably you could use jQuery s parseJSON

[java] Returning JSON response from Servlet to Javascript/JSP page

Examples related to java

Examples related to json

Examples related to gson