JSON PARSER - USING JERSEY

                                 JSON PARSER - USING JERSEY

Now a days most of the companies building webservices using REST instead of SOAP.

Representational State Transfer or REST basically means that each unique URL is a representation of some object. You can get the contents of that object using an HTTP GET, to delete it, you then might use a POST, PUT, or DELETE to modify the object .

REST uses existing principles and protocols of the Web are enough to create robust Web services. This means that developers who understand HTTP and XML can start building Web services right away, without needing any toolkits beyond what they normally use for Internet application development.

JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write. It is easy for machines to parse and generate.

JSON is a text format that is completely language independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. These properties make JSON an ideal data-interchange language.

JSON is built on two structures:

• A collection of name/value pairs. In various languages, this is realized as an object, record, struct, dictionary, hash table, keyed list, or associative array.
• An ordered list of values. In most languages, this is realized as an array, vector, list, or sequence.

In JSON, they take on these forms:

An object is an unordered set of name/value pairs. An object begins with { (left brace) and ends with } (right brace). Each name is followed by : (colon) and the name/value pairs are separated by , (comma).

An array is an ordered collection of values. An array begins with [ (left bracket) and ends with ] (right bracket). Values are separated by , (comma).

A value can be a string in double quotes, or a number, or true or false or null, or an object or an array. These structures can be nested.

A string is a sequence of zero or more Unicode characters, wrapped in double quotes, using backslash escapes. A character is represented as a single character string. A string is very much like a C or Java string.

A number is very much like a C or Java number, except that the octal and hexadecimal formats are not used.

{

"employees": [

{ "firstName":"Raghu" , "lastName":"Juluri" }, 

{ "firstName":"Dinesh" , "lastName":"Gunda" }, 

{ "firstName":"Kumar" , "lastName":"Prabhu" }

]

}

JSON object can be parsed using jersey. 

Download Jersey Resource bundle  jersey-bundle.jar , JSON and add jars to the classpath.

     public void parseJson(String json) {

        try {

            JSONObject jsonObj = new JSONObject(json);

            String[] keys = JSONObject.getNames(jsonObj);

            for (String key : keys) {

                if (jsonObj.get(key) instanceof JSONObject) {

                    JSONObject innerData = jsonObj.getJSONObject(key);

                    // process inner Json Object

                } else if (jsonObj.get(key) instanceof JSONArray) {

                    JSONArray innerArray = jsonObj.getJSONArray(key);

                    for (int i = 0; i < innerArray.length(); i++) {

                        JSONObject innerJsonArray = innerArray.getJSONObject(i);

                        //Process JSON Object present in the Array }

                    }

                } else {

                    System.out.println("Key : " + key + " Value : " +

                                       jsonObj.get("key"));

                }

            }

        } catch (JSONException e) {

            e.printStackTrace();

        }

    }