json是一种与语言无关的数据交换的格式,
作用:
1.使用ajax进行前后台数据交换
2.移动端与服务端的数据交换
1.Json的格式与解析
json有两种格式:
1)对象格式:{"key1":obj,"key2":obj,"key3":obj...}
2)数组/集合格式:[obj,obj,obj...]
例如:user对象 用json数据格式表示
{"username":"zhangsan","age":28,"password":"123","addr":"北京"}
List<Product> 用json数据格式表示
[{"pid":"10","pname":"小米4C"},{"pid":"10","pname":"小米4C"},{"pid":"10","pname":"小米4C"}]
注意:对象格式和数组格式可以互相嵌套
json的解析:
json是js的原生内容,也就意味着js可以直接取出json对象中的数据
例子:var json = {
"key1":"value1",
"key2":{"firstname":"张","lastname":"三丰","age":100},
"key3":[
{"name":"小双","age":28,"addr":"扬州"},
{"name":"建宁","age":18,"addr":"紫禁城"},
{"name":"阿珂","age":10,"addr":"山西"},
]
};
//直接获取元素值
alert(json.key2.lastname);
alert(json.key3[2].name);