![Example: JSON Object var myJSONObject = {"bindings": [ {"ircEvent": "PRIVMSG", "method": "newURI", "regex": "^http://.*"}, {"ircEvent": "PRIVMSG", "method": "deleteURI", "regex": "^delete.*"}, {"ircEvent": "PRIVMSG", "method": "randomURI", "regex": "^random.*"} ] };](https://image.slidesharecdn.com/j-s-o-n-120219575328402-3-111030153145-phpapp01/85/J-s-o-n-120219575328402-3-8-320.jpg)
![Example: JSON Object Cont.. In this example, a JSON JavaScript object is created containing a single member "bindings", which contains an array containing three objects, each containing "ircEvent", "method", and "regex" members Members can be retrieved using dot or subscript operators myJSONObject.bindings[0].method // "newURI"](https://image.slidesharecdn.com/j-s-o-n-120219575328402-3-111030153145-phpapp01/85/J-s-o-n-120219575328402-3-9-320.jpg)
![How to Receive JSON Data at the Client Side JSON data is received as a string Calling eval() will generate JSON object in JavaScript code > var JSONdata = eval(req.responseText); Once you have JSON object, you can use . Notation to access its properties > var name = JSONdata.name; > var address = JSONdata.addresses[3]; > var streetname = JSONdata.addresses[3].street;](https://image.slidesharecdn.com/j-s-o-n-120219575328402-3-111030153145-phpapp01/85/J-s-o-n-120219575328402-3-15-320.jpg)
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- 1. Introduction to Introduction to JSON (JavaScript (JavaScript Object Notation)
- 2. Topics What is JSON? JSON Data Structure > JSON Object > JSON text How to send and receive JSON data at both client and server sides Resources
- 3. What is JSON? Lightweight data-interchange format > Compared to XML Simple format > Easy for humans to read and write > Easy for machines to parse and generate JSON is a text format > Programming language independent > Uses conventions that are familiar to programmers of the C family of languages, including C, C++, C#, Java, JavaScript, Perl, Python
- 4. JSON Object
- 5. JSON 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 These are universal data structures supported by most modern programming languages
- 6. JSON Object Notation A JSON object is an unordered set of name/value pairs A JSON 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)
- 7. JSON and JavaScript JSON is a subset of the object literal notation of JavaScript > JSON can be used in the JavaScript language with no muss or fuss
- 8. Example: JSON Object var myJSONObject = {"bindings": [ {"ircEvent": "PRIVMSG", "method": "newURI", "regex": "^http://.*"}, {"ircEvent": "PRIVMSG", "method": "deleteURI", "regex": "^delete.*"}, {"ircEvent": "PRIVMSG", "method": "randomURI", "regex": "^random.*"} ] };
- 9. Example: JSON Object Cont.. In this example, a JSON JavaScript object is created containing a single member "bindings", which contains an array containing three objects, each containing "ircEvent", "method", and "regex" members Members can be retrieved using dot or subscript operators myJSONObject.bindings[0].method // "newURI"
- 10. Text to Object Conversion in JavaScript code var myObject = eval('(' + myJSONtext + ')'); To convert a JSON text into an JSON object, use the eval() function > eval() invokes the JavaScript compiler > Since JSON is a proper subset of JavaScript, the compiler will correctly parse the text and produce an object structure
- 11. Security & JSON Parser // Include http://www.json.org/json.js var myObject = myJSONtext.parseJSON(); eval() can compile and execute any JavaScript program, so there can be security issues (cross-site scripting) > Use eval() when the source can be trusted When security is a concern - the source cannot be trusted -, it is better to use a JSON parser > A JSON parser will only recognize JSON text and so is much safer
- 12. Object to Text Conversion var myJSONText = myObject.toJSONString(); You can convert JSON object into JSON text JSON does not support cyclic data structure > Do not give cyclical structures to the JSON stringifier
- 13. How to Send & Receive JSON Data at Both Client and Server Side
- 14. How to Generate/Send JSON Data at the Server Side Create JSONObject Java object Add name/value pairs using put method Convert it to String type using toString method and send it to the client with content-type as “text/xml” or “text/plain” myString = new JSONObject().put("JSON", "Hello, World!").toString(); // myString is {"JSON": "Hello, World"}
- 15. How to Receive JSON Data at the Client Side JSON data is received as a string Calling eval() will generate JSON object in JavaScript code > var JSONdata = eval(req.responseText); Once you have JSON object, you can use . Notation to access its properties > var name = JSONdata.name; > var address = JSONdata.addresses[3]; > var streetname = JSONdata.addresses[3].street;
- 16. How to Generate/Send JSON Data at the Client Side Use “POST” HTTP method in the open method of the XMLHttpRequest object Create JSON JavaScript object Pass JSON JavaScript object in the send method of XMLHttpRequest object
- 17. How to Generate/Send JSON Data at the Client Side Cont… var carAsJSON = JSON.stringify(car); var url = "JSONExample?timeStamp=" + new Date().getTime(); createXMLHttpRequest(); xmlHttp.open("POST", url, true); xmlHttp.onreadystatechange = handleStateChange; xmlHttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); xmlHttp.send(carAsJSON);
- 18. How to Receive JSON Data at the Server Side Read the JSON data as a String type Create JSONObject Java object from the string String json = readJSONStringFromRequestBody(request); //Use the JSON-Java binding library to create a JSON object in Java JSONObject jsonObject = null; try { jsonObject = new JSONObject(json); } catch(ParseException pe) { }
- 19. JSON Resources Introducing JSON > http://www.json.org/ JSON in JavaScript > http://www.json.org/js.html