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 · Accepted 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

User · Answer

I used JSONObject as shown below in Servlet       JSONObject jsonReturn   new JSONObject         NhAdminTree   AdminTasks GetNeighborhoodTreeForNhAdministrator  connection  bwcon  userName        map   new HashMap lt String  String gt         map put  Status    Success        map put  FailureReason    None        map put  DataElements    2         jsonReturn   new JSONObject        jsonReturn accumulate  Header   map        List lt String gt  list   new ArrayList lt String gt         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

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