The rules of JSON are simple: an object is an unordered collection of "name/value" pairs. An object starts with "{" (left bracket) and ends with "}" (right bracket). Each "name" is followed by a ":" (colon); "name/value" pairs are separated by a "," (comma). For specific details, please refer to http://www.json.org/json-zh.html
This article has an introductory article. You can also refer to JSON Learning Complete Manual with Graphics
A simple example:
js code
function showJSON() {
var user =
{
"username":"andy",
"age":20,
"info ": { "tel": "123456", "cellphone": "98765"},
"address":
[
{"city":"beijing","postcode":"222333" },
{"city":"newyork","postcode":"555666"}
]
}
alert(user.username);
alert(user.age);
alert(user.info.cellphone);
alert(user.address[0].city);
alert(user.address[0].postcode);
}
This represents a user object with attributes such as username, age, info, address, etc.
You can also use JSON to simply modify the data, modify the above example
js code
function showJSON() {
var user =
{
"username":"andy",
"age":20,
" info": { "tel": "123456", "cellphone": "98765"},
"address":
[
{"city":"beijing","postcode":"222333 "},
{"city":"newyork","postcode":"555666"}
]
}
alert(user.username);
alert(user.age) ;
alert(user.info.cellphone);
alert(user.address[0].city);
alert(user.address[0].postcode);
user.username = "Tom";
alert(user.username);
}
JSON provides the json.js package, download it from http://www.json.org/json.js , introduce it and then simply use object.toJSONString() to convert it into JSON data.
js code
function showCar() {
var carr = new Car("Dodge", "Coronet R/T", 1968, "yellow");
alert(carr.toJSONString());
}
function Car(make, model , year, color) {
this.make = make;
this.model = model;
this.year = year;
this.color = color;
}
You can use eval to convert JSON characters to Object
js code
function myEval() {
var str = '{ "name": "Violet", "occupation": "character" }';
var obj = eval('(' str ')');
alert(obj.toJSONString());
}
or use parseJSON() method
js code
function myEval() {
var str = '{ "name": "Violet", "occupation": "character" }';
var obj = str.parseJSON();
alert(obj.toJSONString());
}
Use prototype below Write an ajax example of JSON.
First write a servlet (mine is servlet.ajax.JSONTest1.java) and write a sentence
java code
response.getWriter().print("{ "name": "Violet", " occupation": "character" }");
Write an ajax request in the page
js code
function sendRequest() {
var url = "/MyWebApp/JSONTest1";
var mailAjax = new Ajax.Request(
url,
{
method: 'get',
onComplete: jsonResponse
}
);
}
function jsonResponse(originalRequest) {
alert(originalRequest.responseText);
var myobj = originalRequest.responseText.parseJSON();
alert(myobj.name);
}
JSON methods are provided in prototype-1.5.1.js , String.evalJSON(), you can modify the above method without using json.js.
js code
function jsonResponse(originalRequest) {
alert(originalRequest.responseText);
var myobj = originalRequest.responseText.evalJSON(true);
alert(myobj.name);
}
JSON also provides the java jar package http://www.json.org/java/index.html The API is also very simple. Here is an example
Fill in the javascript Request parameters
js code
function sendRequest() {
var carr = new Car("Dodge", "Coronet R/T", 1968, "yellow");
var pars = "car=" carr.toJSONString();
var url = " /MyWebApp/JSONTest1";
var mailAjax = new Ajax.Request(
url,
{
method: 'get',
parameters: pars,
onComplete: jsonResponse
}
);
}
Using the JSON request string, you can simply generate JSONObject and parse it, modify the servlet to add JSON processing (you need to use json.jar)
java code
private void doService(HttpServletRequest request, HttpServletResponse response ) throws IOException {
String s3 = request.getParameter("car");
try {
JSONObject jsonObj = new JSONObject(s3);
System.out.println(jsonObj.getString(" model"));
System.out.println(jsonObj.getInt("year"));
} catch (JSONException e) {
e.printStackTrace();
}
response.getWriter().print("{ "name": "Violet", "occupation": "character" }");
}
You can also use JSONObject to generate a JSON string , modify the servlet
java code
private void doService( HttpServletRequest request, HttpServletResponse response) throws IOException {
String s3 = request.getParameter("car");
try {
JSONObject jsonObj = new JSONObject(s3);
System.out.println( jsonObj.getString("model"));
System.out.println(jsonObj.getInt("year"));
} catch (JSONException e) {
e.printStackTrace();
}
JSONObject resultJSON = new JSONObject();
try {
resultJSON.append("name", "Violet")
.append("occupation", "developer")
.append("age", new Integer(22));
System.out.println(resultJSON.toString());
} catch (JSONException e) {
e.printStackTrace();
}
response.getWriter().print(resultJSON.toString());
}
js code
function jsonResponse(originalRequest) {
alert(originalRequest.responseText);
var myobj = originalRequest.responseText. evalJSON(true);
alert(myobj.name);
alert(myobj.age);
}
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