ajax 对 Json 格式的解析

摘要: 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：

response.setCharacterEncoding("utf-8");
response.setContentType("text/json;charset=UTF-8");
PrintWriter out = null;
String count = "{ "firstName": "Brett" };
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":"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({
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();
}