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;
    }
}

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; }
}

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”}]。