ajax 对 Json 格式的解析(转)

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":"[e-mail]","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：

response.setCharacterEncoding("utf-8");
        response.setContentType("text/json;charset=UTF-8");
        PrintWriter out = null;
        String count = "<span style="color: #000000;">{ "firstName": "Brett" }</span>

;
        try {
            out = response.getWriter();
        } catch (Exception e) {
            e.printStackTrace();
        }
        out.print(count);
        out.flush();

 这样就能在前台页面弹出提示框：firstName = Brett。

 

2.多个键/值对和上面的情况一样

 

3.解析Json如下数组：

{

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

$.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) {
for(int i = 0; i < data.length; i++) { //循环后台传过来的Json数组
     var datas = data[i];
     alert(datas.firstName);
     alert(datas.lastName);
     alert(datas.email);
}
}
});

 

4.解析如下Json数据

{ "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" }
 ]
}

 

$.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) {
var pro = data.programmers; // pro为programmers的一个数组
for(int i = 0; i < pro.length; i++) { //循环后台传过来的Json数组
     var datas = pro[i];
     alert(pro.firstName);
     alert(pro.lastName);
     alert(pro.email);
}
var aut = data.authors; // aut为authors的一个数组
for(int i = 0; i < aut.length; i++) { //循环后台传过来的Json数组
     var datas = aut[i];
     alert(aut.firstName);
     alert(aut.lastName);
     alert(aut.genre);
}
var mus = data.musicians; // aut为authors的一个数组
for(int i = 0; i < mus.length; i++) { //循环后台传过来的Json数组
     var datas = mus[i];
     alert(mus.firstName);
     alert(mus.lastName);
     alert(mus.instrument);
}

}
});

 

 5.

{ "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":"[e-mail]","created":"2012-03-22T09:36:44+0800","state":"enabled","account":"xian1","accounttype":0,"domainid":2,"domain":"Server","timezone":"Asia/Shanghai"}]} ] } }

 

 

 

 

$.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) {
var accounts = data.listaccountsresponse.account; //取到“account”中的数据
for(int i = 0; i < accounts.length; i++) { //循环后台传过来的Json数组
     var datas = accounts[i];
     alert(datas.id);
     alert(datas.name);
     alert(datas.accounttype);
     ..........
}
}
});

 

-----这里是自己写的一个后台传值----------------------------------------------------------------------------------------------------------

 

@RequestMapping(value="/applyVm/listApplyVmCount", method={RequestMethod.GET, RequestMethod.POST})
    public void listApplyVmCount(HttpServletRequest request, HttpServletResponse response) {
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/json;charset=UTF-8");
        PrintWriter out = null;
        String count = "";
        try {
            out = response.getWriter();
            Map<String, Integer> map = applyVmService.findApplyVmCount();
            Gson gson = new Gson();
            count = gson.toJson(map);
        } catch (Exception e) {
            e.printStackTrace();
        }
        out.print(count);
        out.flush();
    }