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json学习笔记

2012-03-21 10:17  AceYue  阅读(1382)  评论(5编辑  收藏  举报

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:

View Code
<%@ 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:

View Code
 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:

View Code
 public class Person
{
public string Name { get; set; }
public int Age { get; set; }
}

简单实现:

View Code
protected void 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

View Code
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

View Code
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

View Code
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

View Code
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

View Code
//        在后台替换字符串适用范围比较窄,如果考虑到全球化的有多种语言还会更麻烦。
//2. 利用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;
}
//简单Demo :
//ChangeDateFormat("\/Date(1294499956278+0800)\/");