Newtonsoft.Json(Json.Net)学习笔记

Newtonsoft.Json，一款.NET中开源的Json序列化和反序列化类库(下载地址http://json.codeplex.com/)。

下面是Json序列化和反序列化的简单封装：

/// <summary>
/// Json帮助类 /// </summary>
public class JsonHelper { /// <summary>
/// 将对象序列化为JSON格式 /// </summary>
/// <param name="o">对象</param>
/// <returns>json字符串</returns>
public static string SerializeObject(object o) { string json = JsonConvert.SerializeObject(o); return json; } /// <summary>
/// 解析JSON字符串生成对象实体 /// </summary>
/// <typeparam name="T">对象类型</typeparam>
/// <param name="json">json字符串(eg.{"ID":"112","Name":"石子儿"})</param>
/// <returns>对象实体</returns>
public static T DeserializeJsonToObject<T>(string json) where T : class { JsonSerializer serializer = new JsonSerializer(); StringReader sr = new StringReader(json); object o = serializer.Deserialize(new JsonTextReader(sr), typeof(T)); T t = o as T; return t; } /// <summary>
/// 解析JSON数组生成对象实体集合 /// </summary>
/// <typeparam name="T">对象类型</typeparam>
/// <param name="json">json数组字符串(eg.[{"ID":"112","Name":"石子儿"}])</param>
/// <returns>对象实体集合</returns>
public static List<T> DeserializeJsonToList<T>(string json) where T : class { JsonSerializer serializer = new JsonSerializer(); StringReader sr = new StringReader(json); object o = serializer.Deserialize(new JsonTextReader(sr), typeof(List<T>)); List<T> list = o as List<T>; return list; } /// <summary>
/// 反序列化JSON到给定的匿名对象. /// </summary>
/// <typeparam name="T">匿名对象类型</typeparam>
/// <param name="json">json字符串</param>
/// <param name="anonymousTypeObject">匿名对象</param>
/// <returns>匿名对象</returns>
public static T DeserializeAnonymousType<T>(string json, T anonymousTypeObject) { T t = JsonConvert.DeserializeAnonymousType(json, anonymousTypeObject); return t; } }

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为进一步理解Newtonsoft，写了一些测试的例子：

/// <summary>
/// Json测试 /// </summary>
public class JsonTest : IRun { public void Run() { Student sdudent = new Student(); sdudent.ID = 1; sdudent.Name = "陈晨"; sdudent.NickName = "石子儿"; sdudent.Class = new Class() { Name = "CS0216", ID = 0216 }; //实体序列化和反序列化
string json1 = JsonHelper.SerializeObject(sdudent); //json1 : {"ID":1,"Name":"陈晨","NickName":"石子儿","Class":{"ID":216,"Name":"CS0216"}}
Student sdudent1 = JsonHelper.DeserializeJsonToObject<Student>(json1); //实体集合序列化和反序列化
List<Student> sdudentList = new List<Student>() { sdudent, sdudent1 }; string json2 = JsonHelper.SerializeObject(sdudentList); //json: [{"ID":1,"Name":"陈晨","NickName":"石子儿","Class":{"ID":216,"Name":"CS0216"}},{"ID":1,"Name":"陈晨","NickName":"石子儿","Class":{"ID":216,"Name":"CS0216"}}]
List<Student> sdudentList2 = JsonHelper.DeserializeJsonToList<Student>(json2); //DataTable序列化和反序列化
DataTable dt = new DataTable(); dt.TableName = "Student"; dt.Columns.Add("ID", typeof(int)); dt.Columns.Add("Name"); dt.Columns.Add("NickName"); DataRow dr = dt.NewRow(); dr["ID"] = 112; dr["Name"] = "战三"; dr["NickName"] = "小三"; dt.Rows.Add(dr); string json3 = JsonHelper.SerializeObject(dt); //json3 : [{"ID":112,"Name":"战三","NickName":"小三"}]
DataTable sdudentDt3 = JsonHelper.DeserializeJsonToObject<DataTable>(json3); List<Student> sdudentList3 = JsonHelper.DeserializeJsonToList<Student>(json3); //验证对象和数组
Student sdudent4 = JsonHelper.DeserializeJsonToObject<Student>("{\"ID\":\"112\",\"Name\":\"石子儿\"}"); List<Student> sdudentList4 = JsonHelper.DeserializeJsonToList<Student>("[{\"ID\":\"112\",\"Name\":\"石子儿\"}]"); //匿名对象解析
var tempEntity = new { ID = 0, Name = string.Empty }; string json5 = JsonHelper.SerializeObject(tempEntity); //json5 : {"ID":0,"Name":""}
tempEntity = JsonHelper.DeserializeAnonymousType("{\"ID\":\"112\",\"Name\":\"石子儿\"}", tempEntity); var tempStudent = new Student(); tempStudent = JsonHelper.DeserializeAnonymousType("{\"ID\":\"112\",\"Name\":\"石子儿\"}", tempStudent); Console.Read(); } } /// <summary>
/// 学生信息实体 /// </summary>
public class Student { public int ID { get; set; } public string Name { get; set; } public string NickName { get; set; } public Class Class { get; set; } } /// <summary>
/// 学生班级实体 /// </summary>
public class Class { public int ID { get; set; } public string Name { get; set; } }

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使用Json帮助类时，有两点需要注意下：

1. 通常使用调用实体序列化SerializeObject()和反序列化DeserializeJsonToObject()两个方法就可以了。但有些情况下我们解析json字符串时，可能没有对应的实体类型（或者说不想添加对应的实体类），这时候可以用匿名对象解析方法DeserializeAnonymousType()，方便快捷，对应代码如下：

//匿名对象解析
var tempEntity = new { ID = 0, Name = string.Empty }; string json5 = JsonHelper.SerializeObject(tempEntity); //json5 : {"ID":0,"Name":""}
tempEntity = JsonHelper.DeserializeAnonymousType("{\"ID\":\"112\",\"Name\":\"石子儿\"}", tempEntity); Console.WriteLine(tempEntity.ID + ":" + tempEntity.Name);

2. Json的两种结构数组和对象解析时略有不同。Json对象一般转换成实体，Json数组一般转换成实体集合。代码如下：

//验证对象和数组
Student sdudent4 = JsonHelper.DeserializeJsonToObject<Student>("{\"ID\":\"112\",\"Name\":\"石子儿\"}"); List<Student> sdudentList4 = JsonHelper.DeserializeJsonToList<Student>("[{\"ID\":\"112\",\"Name\":\"石子儿\"}]");

简单解释下Json对象和数组的含义：

对象是以“{”（左括号）开始，“}”（右括号）结束。每个“名称”后跟一个“:”（冒号）；“‘名称/值’ 对”之间运用 “,”（逗号）分隔。名称用引号括起来；值如果是字符串则必须用括号，数值型则不须要。例如：{"ID":"112","Name":"石子儿"}。

数组是值（value）的有序集合。一个数组以“[”（左中括号）开始，“]”（右中括号）结束。值之间运用 “,”（逗号）分隔。例如：[{"ID":"112","Name":"石子儿"},{"ID":"113","Name":"陈晨"}]。