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Json简单学习

2012-05-10 13:38 148 查看
JSON:JavaScript 对象表示法(JavaScript Object Notation)。

JSON 是存储和交换文本信息的语法。类似 XML。

JSON 比 XML 更小、更快,更易解析。

实例:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="json_test.aspx.cs" Inherits="Web_SoftAceTest.json.json_test" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0
Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html
xmlns="http://www.w3.org/1999/xhtml" >

<head runat="server">

title>Untitled Page</title>

<script type="text/javascript">

var text = '{employees:[' '{"LastName":"Getes","FirstName":"Bill"},' '{"LastName":"Yue","FirstName":"Ace"},''{"LastName":"Bush","FirstName":"George"}]}';

var obj = eval("(" text ")");

</script> <

/head>

<body>

<form id="form1"
runat="server"> <

div> <p> Name:<span
id="sp_name"></span><br
/> Age:<span
id="sp_age"></span><br
/> Address:<span
id="sp_address"></span><br
/> Phone:<span
id="sp_phone"></span> </p>

<%--<script
type="text/javascript"> var JsonObject
= { employees: [ {
"Name": "AceYue", "Age": "22", "Address": "Guangdong
Shenzheng", "Phone": "1234567" }, {
"Name": "Getes", "Age": "52", "Address": "Americ", "Phone": "555-1234567" } ] };

document.getElementById("sp_name").innerHTML
=
JsonObject.employees[1].Name;

document.getElementById("sp_age").innerHTML
=
JsonObject.employees[1].Age;

document.getElementById("sp_address").innerHTML
=
JsonObject.employees[1].Address;

document.getElementById("sp_phone").innerHTML
=
JsonObject.employees[1].Phone;

</script>--%>

<p> FirstName:<span
id="sp_firstname"></span><br
/> LastName:<span
id="sp_lastname"></span> </p>

<script type="text/javascript">

document.getElementById("sp_firstname").innerHTML
=
obj.employees[0].FirstName;

document.getElementById("sp_lastname").innerHTML
=
obj.employees[0].LastName;

</script>

</div>

form>

body>

html>

类似 XML

JSON 是纯文本

JSON 具有“自我描述性”(人类可读)

JSON 具有层级结构(值中存在值)

JSON 可通过 JavaScript 进行解析

JSON 数据可使用 AJAX 进行传输

相比 XML 的不同之处

没有结束标签

更短

读写的速度更快

能够使用内建的 JavaScript eval() 方法进行解析

使用数组

不使用保留字

JSON 值可以是:

数字(整数或浮点数)

字符串(在双引号中)

逻辑值(true 或 false)

数组(在方括号中)

对象(在花括号中)

null

json序列化与反序列化

json的序列化需要用到DataContractJsonSerializer类,在命名空间System.Runtime.Serialization.Json;下。.NET
Framework 3.5需要添加System.ServiceModel.Web引用;.NET Framework
4在System.Runtime.Serialization中。

jsonhelper类:

public class JsonHelper {

/// <summary>///
json序列号 /// </summary>

/// <typeparam
name="T"></typeparam>

/// <param name="t"></param>

/// <returns></returns>

public static string JsonSerializa<T>(T t)

{

DataContractJsonSerializer zer = new DataContractJsonSerializer(typeof(T));

MemoryStream ms = new
MemoryStream();

zer.WriteObject(ms, t);

string jsonstring =
Encoding.UTF8.GetString(ms.ToArray());

ms.Close();

return
jsonstring;

}
/// <summary>///
json反序列化 /// </summary>

/// <typeparam
name="T"></typeparam>/

// <param
name="strjson"></param>

/// <returns></returns>

public static T JsonDeserializa<T>(string strjson)

{

DataContractJsonSerializer zer = new DataContractJsonSerializer(typeof(T));

MemoryStream ms = new
MemoryStream(Encoding.UTF8.GetBytes(strjson));

T obj = (T)zer.ReadObject(ms);

return
obj;

}

}

Person类:

publicclass Person
{ publicstring Name { get; set; } publicint Age { get; set; }
}

简单实现:

protectedvoid
Page_Load(object sender, EventArgs e)

{

Person p =
new
Person();

p.Name =
"Ace";

p.Age =
22;
string json =
JsonHelper.JsonSerializa<Person>(p);

Response.Write(json);

}

json序列化处理日期类型的处理

JSON格式不直接支持日期和时间。DateTime值值显示为“/Date(700000
0500)/”形式的JSON字符串,其中第一个数字(在提供的示例中为 700000)是 GMT 时区中自 1970 年 1 月 1
日午夜以来按正常时间(非夏令时)经过的毫秒数。该数字可以是负数,以表示之前的时间。示例中包括“
0500”的部分可选,它指示该时间属于Local类型,即它在反序列化时应转换为本地时区。如果没有该部分,则会将时间反序列化为Utc。

修改jsonhelper类需用到的名称空间:

using System.Runtime.Serialization.Json;
using System.IO; using System.Text; using System.Text.RegularExpressions; using System.Collections.Generic;//List名称空间

jsonhelper类的修改:

public class JsonHelper {
///
<summary>/// json序列化 ///
</summary>

/// <typeparam
name="T"></typeparam>

/// <param
name="t"></param>

/// <returns></returns>

public static string JsonSerializer<T>(T
t)

{

DataContractJsonSerializer zer = new
DataContractJsonSerializer(typeof(T));

MemoryStream ms = new
MemoryStream();

zer.WriteObject(ms,
t);

string jsonstring =
Encoding.UTF8.GetString(ms.ToArray());

ms.Close();
string p =
@"\\/Date\((\d )\ \d \)\\/";

MatchEvaluator me = new
MatchEvaluator(ConvertJsonDateToDateString)

; Regex rg = new
Regex(p);

jsonstring = rg.Replace(jsonstring,
me);

return
jsonstring;

}
/// <summary>/// json反序列化 ///
</summary>

/// <typeparam
name="T"></typeparam>

/// <param
name="jsonstring"></param>

///
<returns></returns>

public static T
JsonDeserializer<T>(string
jsonstring)

{

string p =
@"\d{4}-\d{2}-\d{2}\s\d{2}:\d{2}:\d{2}";

MatchEvaluator me = new
MatchEvaluator(ConvertDateTimeToJsonDate);

Regex rg = new
Regex(p);

jsonstring = rg.Replace(jsonstring,
me);

DataContractJsonSerializer zer = new
DataContractJsonSerializer(typeof(T));

MemoryStream ms=new
MemoryStream(Encoding.UTF8.GetBytes(jsonstring));

T obj =
(T)zer.ReadObject(ms);

return
obj;

}
/// <summary>///
将Json序列化的时间由/Date(1294499956278 0800)转为字符串 ///
</summary>/

// <param
name="m"></param>

///
<returns></returns>

private static string
ConvertJsonDateToDateString(Match m)

{

string result =
string.Empty;

DateTime dt = new
DateTime(1970,1,1);

dt =
dt.AddMilliseconds(long.Parse(m.Groups[1].Value));

dt =
dt.ToLocalTime();

result = dt.ToString("yyyy-MM-dd
HH:mm:ss");

return
result;

}
/// <summary>///
将时间字符串转化成json时间 ///
</summary>

/// <param
name="m"></param>

///
<returns></returns>

private static string
ConvertDateTimeToJsonDate(Match m)

{

string result =
string.Empty;

DateTime dt =
DateTime.Parse(m.Groups[0].Value);

dt =
dt.ToUniversalTime();

TimeSpan ts = dt -
DateTime.Parse("1970-01-01");

result = string.Format("\\/Date({0}
0800)\\/",ts.TotalMilliseconds);

return
result;

}

}

person类的修改:

public class Person { public string Name { get; set; } public int Age { get; set; } public DateTime LastLoginTime { get; set; }
}

实例调用及对集合、字典、数组的处理:

protected
void Page_Load(object sender, EventArgs
e)

{

Person ps = new
Person();

ps.Age = 22;

ps.Name = "Ace";

ps.LastLoginTime =
DateTime.Now;
string
json =
JsonHelper.JsonSerializer<Person>(ps)

; Response.Write(json);

List<Person> lt = new
List<Person>()

{

new Person(){Name="Ace",Age=22,LastLoginTime=DateTime.Now},

new Person(){Name="Getes",Age=55,LastLoginTime=DateTime.Now}

};

string jsonstring =
JsonHelper.JsonSerializer<List<Person>>(lt);

Response.Write(jsonstring);

Dictionary<string, string> dy = new Dictionary<string, string>();

dy.Add("Name", "Ace");

dy.Add("Age","22");
string json1 =
JsonHelper.JsonSerializer<Dictionary<string, string>>(dy);

Response.Write(json1);

}

用javascript处理

function ChangeDateFormat(jsondate)
{

jsondate = jsondate.replace("/Date(", "").replace(")/",
"");

if (jsondate.indexOf("") > 0)
{

jsondate = jsondate.substring(0, jsondate.indexOf(""));

}

else if (jsondate.indexOf("-")
> 0)
{

jsondate = jsondate.substring(0, jsondate.indexOf("-"));

}

var date = new Date(parseInt(jsondate, 10));

var month = date.getMonth() 1 < 10 ? "0"
(date.getMonth() 1) : date.getMonth()
1;

var currentDate = date.getDate() < 10 ? "0"
date.getDate() : date.getDate();

return date.getFullYear() "-"
month "-"
currentDate;

}
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