JSON详解以及在android中的使用.ppt

JSON
讲解:李志敏
概念
JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write. It is easy for machines to parse and generate. It is based on a subset of the JavaScript Programming Language, Standard ECMA-262 3rd Edition - December 1999. JSON is a text format that pletely language independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. These properties make JSON an ideal data-interchange language.
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JSON书写格式
JSON的规则很简单:对象是一个无序的“‘名称/值’对”集合。
一个对象以“{”(左括号)开始,“}”(右括号)结束。每个“名称”后跟一个“:”(冒号);“‘名称/值’对”之间使用“,”(逗号)分隔。
规则如下:
1) 映射用冒号(“:”)表示。名称:值
2) 并列的数据之间用逗号(“,”)分隔。名称1:值1,名称2:值2
3) 映射的集合(对象)用大括号(“{}”)表示。{名称1:值,名称2:值2}
4) 并列数据的集合(数组)用方括号(“[]”)表示。
[
{名称1:值,名称2:值2},
{名称1:值,名称2:值2}
]
5)元素值可具有的类型:string, number, object, array, true, false, null
JSON对象(键值对或键值对的集合)
例1、{ "name": "Obama"}
例2、{ "name": "Romney","age": 56}
例3、{ "city":{"name": "bj"},"weatherinfo":{"weather": "sunny"}}
例4、{
"city":{"name": "北京",“city_id”:"101010100"},
"weatherinfo":{"weather": "sunny","temp":"29度"}
}
JSON数组
例1、 [
{ "name": "张三", "age":22, "email": "zhangsan@" },
{ "name": "李四", "age":23, "email": "lisi@"},
{ "name": "王五", "age":24, "email": "wangwu@" }
]
例2、 { "student":
[
{ "name": "张三", "age":22, "email": "zhangsan@" },
{ "name": "李四", "age":23, "email": "lisi@"},
{ "name": "王五", "age":24, "email": "wangwu@" }
]
}
在javascript中使用json
javascript解析json本身是不需要任何工具包的,也有一些封装好的更方便使用的工具包(下载地址:)
例1、翻译json字符串为json对象并解析
<script language="JavaScript">
var peopleStr='{"firstName": "Brett", "lastName":"McLaughlin" }';
var people=eval('('+peopleStr+')');
//上面两行代码相当于
//var people ={"firstName": "Brett", "lastName":"McLaughlin"};
alert();
alert();
</script>
在javascript中使用json
例2:解析json数组
<script language="JavaScript">
var people =[
{"firstName": "Brett","email": "brett@" },
{"firs