JSON (JavaScript Object Notation)一種簡單的資料格式,比xml更輕巧。 JSON 是JavaScript 原生格式,這意味著在 JavaScript 中處理 JSON 資料不需要任何特殊的 API 或工具包。
JSON的規則很簡單: 對象是一個無序的“‘名稱/值’對”集合。一個對象以“{”(左括弧)開始,“}”(右括弧)結束。每個“名稱”後跟一個“:”(冒號);“‘名稱/值’ 對”之間使用“,”(逗號)分隔。具體細節參考http://www.json.org/json-zh.html
舉個簡單的例子:
js 代碼
- 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);
- }
這表示一個user對象,擁有username, age, info, address 等屬性。
同樣也可以用JSON來簡單的修改資料,修改上面的例子
js 代碼
- 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提供了json.js包,下載http://www.json.org/json.js 後,將其引入然後就可以簡單的使用object.toJSONString()轉換成JSON資料。
js 代碼
- 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;
- }
可以使用eval來轉換JSON字元到Object
js 代碼
- function myEval() {
- var str = '{ "name": "Violet", "occupation": "character" }';
- var obj = eval('(' + str + ')');
- alert(obj.toJSONString());
- }
或者使用parseJSON()方法
js 代碼
- function myEval() {
- var str = '{ "name": "Violet", "occupation": "character" }';
- var obj = str.parseJSON();
- alert(obj.toJSONString());
- }
下面使用prototype寫一個JSON的ajax例子。
先寫一個servlet (我的是servlet.ajax.JSONTest1.java)就寫一句話
java 代碼
- response.getWriter().print("{ \"name\": \"Violet\", \"occupation\": \"character\" }");
再在頁面中寫一個ajax的請求
js 代碼
- 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);
- }
prototype-<st1:chsdate w:st="on" isrocdate="False" islunardate="False" day="30" month="12" year="1899">1.5.1</st1:chsdate>.js中提供了JSON的方法,String.evalJSON(), 可以不使用json.js, 修改上面的方法
js 代碼
- function jsonResponse(originalRequest) {
- alert(originalRequest.responseText);
- var myobj = originalRequest.responseText.evalJSON(true);
- alert(myobj.name);
- }
JSON還提供了java的jar包 http://www.json.org/java/index.html API也很簡單,下面舉個例子
在javascript中填加請求參數
js 代碼
- 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
- }
- );
- }
使用JSON請求字串就可以簡單的產生JSONObject並進行解析,修改servlet添加JSON的處理(要使用json.jar)
java 代碼
- 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\" }");
- }
同樣可以使用JSONObject產生JSON字串,修改servlet
java 代碼
- 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 代碼
- function jsonResponse(originalRequest) {
- alert(originalRequest.responseText);
- var myobj = originalRequest.responseText.evalJSON(true);
- alert(myobj.name);
- alert(myobj.age);
- }
參考
http://www.json.org/js.html
http://www.blogjava.net/Jkallen/archive/2006/03/28/37905.html
http://www.json.org/
http://www.prototypejs.org/learn/json
http://www.json.org/java/index.html
http://www.ibm.com/developerworks/cn/web/wa-ajaxintro10/index.html