How to parse 'HttpServletRequest' with value of key value pair data

Question

I'm sending from my client side an ajax request to my server.

this is the data structure that i'm passing:

data = {"key1" : "value1" , "key2" : {"subkey1": "subvalue1" ,"subkey2" : "subvalue2"}};

on the server side i'm doing the following:

   private Map<String, Object> parseItemData(HttpServletRequest request) {

    Enumeration<String> parameterNames = request.getParameterNames();

    while (parameterNames.hasMoreElements()) {

        String paramName = parameterNames.nextElement();

        String[] paramValues = request.getParameterValues(paramName);

        if(paramName.equals("itemSpecifics"))
        {
            System.out.println(paramName);

            for (int i =0 ; i<paramValues.length; i++)
            {
                System.out.println(paramName +": "+paramValues[i] );
            }
        }
    }
    return item;
}

this is the output that i'm getting:

itemSpecifics: [object Object]

is there any way to do it?

Solution :

in case of nested key value pair, i had to manual use JSON.stringify() for the nested key value in order to send it as JSON.

score 3 · Accepted Answer · edited May 23 '17 at 12:05

3

This may help you.

Use getParameterMap() method to get all key value pairs.

Map<String, String[]> requestParams = request.getParameterMap();

Below code to get JSONObject:

JSONObject jsonObject=null;
        Map<String,String> out = new HashMap<String, String>();
        Map<String,String[]> map = request.getParameterMap();

        for (Map.Entry<String,String[]> mapEntry : map.entrySet()) {

          String value[] = mapEntry.getValue();
          Object object = value.length == 1 ? value[0] : value;
          try {
              jsonObject = new JSONObject((String)object);
              parse(jsonObject,out);

        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        }
        response.getWriter().print(out);

To parse json use parse function : I have taken help from How can I iterate JSONObject to get individual items

public static Map<String,String> parse(JSONObject json , Map<String,String> out) throws JSONException{
        Iterator<String> keys = json.keys();
        while(keys.hasNext()){
            String key = keys.next();
            String val = null;
            try{
                 JSONObject value = json.getJSONObject(key);
                 parse(value,out);
            }catch(Exception e){
                val = json.getString(key);
            }

            if(val != null){
                out.put(key,val);
            }
        }
        return out;
    }

edited May 23 '17 at 12:05

Community

1
1

answered Nov 28 '14 at 07:18

Vishvesh Phadnis

2,448
5
19
35

was trying to use it as Map requestParams = request.getParameterMap(); and cast it while having the right key for that, but it cannot cast from string to map 'Ljava.lang.String; cannot be cast to java.util.Map' – USer22999299 Nov 28 '14 at 07:32
for some reason the get action returning string object insted of Object – USer22999299 Nov 28 '14 at 07:34
getParameterMap() returns Map only. iterate through string to get other values using json or jackson library – Vishvesh Phadnis Nov 28 '14 at 07:37
Map requestParams = request.getParameterMap(); JSONObject jsonObj = (JSONObject)rquestParams.get("itemSpecifics"); By doing that i'm getting the compilation error of Cannot cast from String[] to JSONObject, as the above suggestion.. – USer22999299 Nov 28 '14 at 07:43
I updated code.Please check. or still you facing issue? – Vishvesh Phadnis Nov 28 '14 at 08:44
While doing that and printing the 'jsonObject' , i'm getting: {... , "itemSpecifics":"[object Object]" , ...} Seems like the data is sent the wrong way? – USer22999299 Nov 28 '14 at 09:30
Please post actual json. – Vishvesh Phadnis Nov 28 '14 at 09:50
Updated Answer and added parse function – Vishvesh Phadnis Nov 28 '14 at 10:00
Found the problem , while sending with ajax json with nested key value i have to use JSON.stringify for the nested list other wise the post method will send it as [object Object] and not as json string. Any way your code is working for me :) thanks! – USer22999299 Nov 28 '14 at 10:01

Anurag Anand · Answer 2 · 2014-11-28T08:26:13.223

1

You could try this. As sysout prints [Object,Object] that means there are two String Objects.

Onw of possible way to declare a String Array like this

String[] keyValPair = new String[]{"\"key1\" : \"value1\"","key2:{}"} This is just a guess how container is parsing this Json like data. May be it converts it in two different String Objects put it as a String Array.

    String[] paramValues = request.getParameterValues(paramName);

    if(paramName.equals("itemSpecifics"))
    {
     System.out.println(paramName);

     String[] paramArr = (String[]) paramValues[0];
     String firstKeyVal = paramArr [0];//Contains "key1" : "value1" as String
     String secondKeyVal = paramArr [1];//Contains "key2" : {"subkey1": "subvalue1" ,"subkey2" : "subvalue2"} as String

     String value1= firstKeyVal.split(":")[1];
     String[] subValues = secondKeyVal.substring(secondKeyVal.indexOf("{")+1,secondKeyVal.indexOf("}")).split(",");
    String subVal1 = subValues[0].split(":")[1];
    String subVal2 = subValues[1].split(":")[1];

     System.out.println(paramName+" value1"+value1+" subVal1 "+subVal1+" subVal2 "+subVal2);

     }

The Best way is to pass all parameters as JSON.

edited Nov 28 '14 at 08:26

answered Nov 28 '14 at 07:02

Anurag Anand

500
1
7
13

This is what i'm getting: Cannot cast from String to JSONObject. any idea? – USer22999299 Nov 28 '14 at 07:21
@USer22999299 I do not think you are getting a String, you are getting an array of Objects because `sysout` prints `[object Object]`, it does not print String value.Calling `paramValues[i].toString()` will give the same output. Have you tried this approach. – Anurag Anand Nov 28 '14 at 07:32
while applying the code above, i'm getting the compilation error of Cannot cast from String to JSONObject. paramValues is a String[] – USer22999299 Nov 28 '14 at 07:36
@USer22999299 I have updated my answer, by assuming how container will parse this string data. – Anurag Anand Nov 28 '14 at 08:22

How to parse 'HttpServletRequest' with value of key value pair data

2 Answers2