将实体类或者集合序列化为JSON字符串，将JSON字符串反序列化还原为对象

using System.ServiceModel.Web;//需要添加对该程序集的引用才能引用System.Runtime.Serialize.Json;

using System.Runtime.Serialization;//需要添加对该程序集的引用，才能使用DataContract,DataMember.
using System.Runtime.Serialization.Json;

public class JSONHelper
{
    public static string Serialize<T>(T obj)//序列化为JSON
    {
        System.Runtime.Serialization.Json.DataContractJsonSerializer serializer = new System.Runtime.Serialization.Json.DataContractJsonSerializer(obj.GetType());
        MemoryStream ms = new MemoryStream();
        serializer.WriteObject(ms, obj);
        string retVal = Encoding.Default.GetString(ms.ToArray());
        return retVal;
    }

    public static T Deserialize<T>(string json)//反序列化为对象
    {
        T obj = Activator.CreateInstance<T>();
        MemoryStream ms = new MemoryStream(Encoding.Unicode.GetBytes(json));
        System.Runtime.Serialization.Json.DataContractJsonSerializer serializer = new System.Runtime.Serialization.Json.DataContractJsonSerializer(obj.GetType());
        obj = (T)serializer.ReadObject(ms);
        ms.Close();
        return obj;
    }
}

/// Our Person object to Serialize/Deserialize to JSON
[DataContract] //需引用System.Runtime.Serializable程序集
public class Person
{
    public Person() { }
    public Person(string firstname, string lastname)
    {
        this.FirstName = firstname;
        this.LastName = lastname;
    }

    [DataMember]
    public string FirstName { get; set; }

    [DataMember]
    public string LastName { get; set; }
}


/// Sample code using the above helper methods
/// to serialize and deserialize the Person object

Person myPerson = new Person("Chris", "Pietschmann");

// Serialize
string json = JSONHelper.Serialize<Person>(myPerson);

// Deserialize
myPerson = JSONHelper.Deserialize<Person>(json);