ajax 对 Json 格式的解析

ajax 对 Json 格式的解析

Json 的介绍：

JSON 可以将 JavaScript 对象中表示的一组数据转换为字符串，然后就可以在函数之间轻松地传递这个字符串，或者在异步应用程序中将字符串从 Web 客户机传递给服务器端程序。

按照最简单的形式，可以用下面这样的 JSON 表示名称/值对：

{ "firstName": "Brett" }

这样的键/值对也可以是多个：

{"name":"aaa","sex":"男","age":"20"}
从语法方面来看，这与名称/值对相比并没有很大的优势，但是在这种情况下 JSON 更容易使用，而且可读性更好。

值的数组

当需要表示一组值时，JSON 不但能够提高可读性，而且可以减少复杂性。

如果使用 JSON，就只需将多个带花括号的记录分组在一起：

{ "people": [
  { "firstName": "Brett", "lastName":"McLaughlin", "email": "111111" },
  { "firstName": "Jason", "lastName":"Hunter", "email": "22222" },
  { "firstName": "Elliotte", "lastName":"Harold", "email": "33333" }
]}

可以使用相同的语法表示多个值（每个值包含多个记录）：

{ "programmers": [
  { "firstName": "Brett", "lastName":"McLaughlin", "email": "3333" },
  { "firstName": "Jason", "lastName":"Hunter", "email": "1222" },
  { "firstName": "Elliotte", "lastName":"Harold", "email": "3333" }
 ],
"authors": [
  { "firstName": "Isaac", "lastName": "Asimov", "genre": "science fiction" },
  { "firstName": "Tad", "lastName": "Williams", "genre": "fantasy" },
  { "firstName": "Frank", "lastName": "Peretti", "genre": "christian fiction" }
 ],
"musicians": [
  { "firstName": "Eric", "lastName": "Clapton", "instrument": "guitar" },
  { "firstName": "Sergei", "lastName": "Rachmaninoff", "instrument": "piano" }
 ]
}

Json也可以这样写：

{ "listaccountsresponse" : { "count":1 ,"account" : [ {"id":5,"name":"xian1","accounttype":0,"domainid" :2,"domain":"Server","receivedbytes":649444,"sentbytes":175467975,"vmlimit":"20","vmtotal":2,"vmavailable" :"18","iplimit":"20","iptotal":1,"ipavailable":"19","volumelimit":"20","volumetotal":2,"volumeavailable" :"18","snapshotlimit":"20","snapshottotal":0,"snapshotavailable":"20","templatelimit":"20","templatetotal" :0,"templateavailable":"20","vmstopped":0,"vmrunning":2,"state":"enabled","user":[{"id":5,"username" :"xian1","firstname":"Eric","lastname":"Tang","email":"Wang-Ngai.Tang@pccw.com","created":"2012-03-22T09 :36:44+0800","state":"enabled","account":"xian1","accounttype":0,"domainid":2,"domain":"Server","timezone" :"Asia/Shanghai"}]} ] } }

ajax对Json格式数据的解析 ：

1.对简单json格式的解析：

{ "firstName": "Brett" }

写道 $.ajax({
url:"这里是你要请求的地址",
data:{"id":id}, //以键/值对的形式
async : false,
dataType : "json",
success : function(data) {
alert("firstName = " + data.firstName);
}
});

 注：这里的data是你从后台穿过来的Json字符传串。

后台写法：

Java代码      

1. @RequestMapping(value="/applyVm/listApplyVmCount", method={RequestMethod.GET, RequestMethod.POST})   
2.     public void listApplyVmCount(HttpServletRequest request, HttpServletResponse response) {   
3.         response.setCharacterEncoding("utf-8");   
4.         response.setContentType("text/json;charset=UTF-8");   
5.         PrintWriter out = null;   
6.         String count = "";   
7.         try {   
8.             out = response.getWriter();   
9.             Map map = applyVmService.findApplyVmCount();   
10.             Gson gson = new Gson();   
11.             count = gson.toJson(map);   
12.         } catch (Exception e) {   
13.             e.printStackTrace();   
14.         }   
15.         out.print(count);   
16.         out.flush();   
17.     }