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.NET下 JSON 的一些常用操作

2017-05-27 08:03 471 查看
1.JSON的序列化和反序列化

首先要先添加引用:

代码如下

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using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using Newtonsoft.Json;

namespace PlayJSON

{

class Program

{

static void Main(string[] args)

{

List<StuInfo> list = new List<StuInfo>() { new StuInfo{StuName="张三",StuSex="男",StuAge=11},

new StuInfo{StuName="李四",StuSex="男",StuAge=32},

new StuInfo{StuName="王翠花",StuSex="女",StuAge=64}

};

string jsonStr = JavaScriptConvert.SerializeObject(list); //将对象转换成json存储

Console.WriteLine("JSON字符串"+jsonStr);

Console.ReadLine();

List<StuInfo> newList = new List<StuInfo>();

newList = (List<StuInfo>)JavaScriptConvert.DeserializeObject(jsonStr,typeof(List<StuInfo>)); //反序列化

//StuInfo s = new StuInfo() { StuName = "阿龙", StuSex = "男", StuAge = 33 };

//string sigleJSON = JavaScriptConvert.SerializeObject(s);

//StuInfo newS = (StuInfo)JavaScriptConvert.DeserializeObject(sigleJSON);

//Console.WriteLine("姓名:" + newS.StuName + "---性别:" + newS.StuSex + "--年龄:" + newS.StuAge + "\n\n");

foreach (StuInfo item in newList)

{

Console.WriteLine("姓名:" + item.StuName + "---性别:" + item.StuSex + "--年龄:" + item.StuAge + "\n\n");

}

Console.ReadLine();

}

}

public class StuInfo

{

public string StuName { set; get; }

public string StuSex { set; get; }

public int StuAge { set; get; }

}

}

2.在web中

首先添加一个一般处理文件 Handler1.ashx:用来返回一个json

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/// <summary>

/// Handler1 的摘要说明

/// </summary>

public class Handler1 : IHttpHandler

{

public void ProcessRequest(HttpContext context)

{

context.Response.ContentType = "application/json";

List<StuInfo> list = new List<StuInfo>() { new StuInfo{StuName="张三",StuSex="男",StuAge=11},

new StuInfo{StuName="李四",StuSex="男",StuAge=32},

new StuInfo{StuName="王翠花",StuSex="女",StuAge=64}

};

string jsonStr = JavaScriptConvert.SerializeObject(list);

context.Response.Write(jsonStr);

context.Response.End();

}

public bool IsReusable

{

get

{

return false;

}

}

}

public class StuInfo

{

public string StuName { set; get; }

public string StuSex { set; get; }

public int StuAge { set; get; }

}

前台页面上的调用:这里采用jquery 的ajax请求

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<head runat="server">

<title>JSON</title>

<script src="Scripts/jquery-1.4.1.min.js" type="text/javascript"></script>

<script type="text/javascript">

$(function () {

$("#btnOK").click(function () {

$.ajax({

type: "JSON",

url: "Handler1.ashx",

data: null,

success: function (msg) {

var con="";

for (var i = 0; i < msg.length; i++) {

con += "姓名:" + msg[i].StuName + "--性别:" + msg[i].StuSex + "--" + "--年龄:" + msg[i].StuAge+"<br/>";

}

$("#divContent").html("长度:" + msg.length + "--具体内容:<br/>" + con);

}

});

});

});

</script>

</head>

<body>

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

<div>

<input type="button" id="btnOK" value="点我获得JSON数据" />

<div id="divContent"></div>

</div>

</form>

</body>

现在经常会用到json,因此经常会需要对其进行序列化和反序列化。,.NET Framewok 3.5也提供了JSON对象序列化和反序列化的类,这就是System.Runtime.Serialization.Json 命名空间下的 DataContractJsonSerializer 类。利用这个类,可以实现JSON对象的序列化和反序列化。

现在我提供一个类JSON对象序列化和反序列化的类供参考用:

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/// <summary>

/// JSON帮助类。用于将对象转换为Json格式的字符串,或者将Json的字符串转化为对象。

/// </summary>

public static class JsonHelper

{

/// <summary>

/// 将对象转化为Json字符串

/// </summary>

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

/// <param name="obj">源类型实例</param>

/// <returns>Json字符串</returns>

public static string GetJsonFromObj<T>(T obj)

{

DataContractJsonSerializer jsonSerializer = new DataContractJsonSerializer(obj.GetType());

using (MemoryStream ms = new MemoryStream())

{

jsonSerializer.WriteObject(ms, obj);

return Encoding.UTF8.GetString(ms.ToArray());

}

}

/// <summary>

/// 将Json字符串转化为对象

/// </summary>

/// <typeparam name="T">目标类型</typeparam>

/// <param name="strJson">Json字符串</param>

/// <returns>目标类型的一个实例</returns>

public static T GetObjFromJson<T>(string strJson)

{

T obj = Activator.CreateInstance<T>();

using (MemoryStream ms = new MemoryStream(Encoding.UTF8.GetBytes(strJson)))

{

DataContractJsonSerializer jsonSerializer = new DataContractJsonSerializer(obj.GetType());

return (T)jsonSerializer.ReadObject(ms);

}

}

/// <summary>

/// 将DataTable转换为JSON字符串

/// </summary>

/// <param name="dt">数据表</param>

/// <returns>JSON字符串</returns>

public static string GetJsonFromDataTable(DataTable dt)

{

StringBuilder JsonString = new StringBuilder();

if (dt != null && dt.Rows.Count > 0)

{

JsonString.Append("{ ");

JsonString.Append("\"TableInfo\":[ ");

for (int i = 0; i < dt.Rows.Count; i++)

{

JsonString.Append("{ ");

for (int j = 0; j < dt.Columns.Count; j++)

{

if (j < dt.Columns.Count - 1)

{

JsonString.Append("\"" + dt.Columns[j].ColumnName.ToString() + "\":" + "\"" + dt.Rows[i][j].ToString() + "\",");

}

else if (j == dt.Columns.Count - 1)

{

JsonString.Append("\"" + dt.Columns[j].ColumnName.ToString() + "\":" + "\"" + dt.Rows[i][j].ToString() + "\"");

}

}

if (i == dt.Rows.Count - 1)

{

JsonString.Append("} ");

}

else

{

JsonString.Append("}, ");

}

}

JsonString.Append("]}");

return JsonString.ToString();

}

else

{

return null;

}

}

/// <summary>

/// 将对象转化为Json字符串

/// </summary>

/// <param name="obj">源对象</param>

/// <returns>json数据</returns>

public static string ObjToJson(this object obj)

{

JavaScriptSerializer serialize = new JavaScriptSerializer();

return serialize.Serialize(obj);

}

/// <summary>

/// 将Json字符串转化为对象

/// </summary>

/// <param name="strJson">Json字符串</param>

/// <returns>目标对象</returns>

public static T JsonToObj<T>(string strJson)

{

JavaScriptSerializer serialize = new JavaScriptSerializer();

return serialize.Deserialize<T>(strJson);

}

/// <summary>

/// 将对象转化为Json字符串(控制深度 )

/// </summary>

/// <param name="obj">源对象</param>

/// <param name="recursionDepth">深度</param>

/// <returns>json数据</returns>

public static string ObjToJson(this object obj, int recursionDepth)

{

JavaScriptSerializer serialize = new JavaScriptSerializer();

serialize.RecursionLimit = recursionDepth;

return serialize.Serialize(obj);

}

/// <summary>

/// 将Json字符串转化为对象(控制深度 )

/// </summary>

/// <param name="strJson">Json字符串</param>

/// <param name="recursionDepth">深度</param>

/// <returns>目标对象</returns>

public static T JsonToObj<T>(string strJson, int recursionDepth)

{

JavaScriptSerializer serialize = new JavaScriptSerializer();

serialize.RecursionLimit = recursionDepth;

return serialize.Deserialize<T>(strJson);

}

/// <summary>

/// 将DataTable转换为JSON字符串

/// </summary>

/// <param name="dt">DataTable</param>

/// <returns>json数据</returns>

public static string DataTableToJson(DataTable dt)

{

Dictionary<string, object> dic = new Dictionary<string, object>();

int index = 0;

foreach (DataRow dr in dt.Rows)

{

Dictionary<string, object> result = new Dictionary<string, object>();

foreach (DataColumn dc in dt.Columns)

{

result.Add(dc.ColumnName, dr[dc].ToString());

}

dic.Add(index.ToString(), result);

index++;

}

return ObjToJson(dic);

}

}

使用如下:

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public partial class WebForm1 : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

}

protected void Button1_Click(object sender, EventArgs e)

{

//反序列化成对象

String strJson = "{\"Name\":\"Test123\",\"Url\":\"http://www.126.com/\"}";

Person p1 = JsonHelper.GetObjFromJson<Person>(strJson);

Response.Write("<li>" + p1.Name + " " + p1.Url);

Person p2 = JsonHelper.JsonToObj<Person>(strJson);

Response.Write("<li>" + p2.Name + " " + p2.Url);

}

protected void Button2_Click(object sender, EventArgs e)

{

//对象的序列化

String JSONString = string.Empty;

Person p1 = new Person();

p1.Name = "Test123'\"\n\r\t";

p1.Url = "http://www.126.com/";

JSONString = JsonHelper.GetJsonFromObj<Person>(p1);

Response.Write("<li>" + JSONString);

JSONString = JsonHelper.ObjToJson(p1);

Response.Write("<li>" + JSONString);

}

}

/// <summary>

/// 类对象需要标记为DataContractAttribute

/// </summary>

[DataContractAttribute]

class Person

{

//成员需要标记为 DataMember

[DataMember]

public string Name { set; get; }

[DataMember]

public string Url { set; get; }

}


Json.NET json字符串反序列化为json对象

如何将一个字符串转换为JSON对象呢?如果先创建一个类的话,那就太累了。

var o = new

{

a = 1,

b = "Hello, World!",

c = new[] { 1, 2, 3 },

d = new Dictionary<string, int> { { "x", 1 }, { "y", 2 } }

};

var json = JsonConvert.SerializeObject(o);

现在json是一个字符串。

第一种做法(匿名类):

var anonymous = new { a = 0, b = String.Empty, c = new int[0], d = new Dictionary<string, int>() };

var o2 = JsonConvert.DeserializeAnonymousType(json, anonymous);

Console.WriteLine(o2.b);

Console.WriteLine(o2.c[1]);

第二种做法(匿名类):

var o3 = JsonConvert.DeserializeAnonymousType(json, new { c = new int[0], d = new Dictionary<string, int>() });

Console.WriteLine(o3.d["y"]);

DeserializeAnonymousType 只是借助这个匿名对象参数(anonymous) 反射类型而已,也就是说它和反序列化结果并非同一个对象。正如 o3 那样,我们也可以只提取局部信息。

第三种做法(索引器):

实际上,我们也可以直接反序列化为 JObject,然后通过索引器直接访问。JObject、JProperty 等都继承自 JToken,它重载了基元类型转换操作符,我们可以直接得到实际结果。

var o2 = JsonConvert.DeserializeObject(json) as JObject;

Console.WriteLine((int)o2["a"]);

Console.WriteLine((string)o2["b"]);

Console.WriteLine(o2["c"].Values().Count());

Console.WriteLine((int)o2["d"]["y"]);
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