个人封装！

public sealed class JsonOpration
{
/// <summary>
/// 泛型使用：把指定字符串转换指定对象
/// </summary>
/// <param name="str">需要转换的字符串</param>
/// <param name="s">指定编码格式</param>
public static T ConverSToObject<T>(string str, Encoding s)
{
byte[] buffer = s.GetBytes(str);
DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(T));
MemoryStream stream = new MemoryStream(buffer);
T user = (T)serializer.ReadObject(stream);
stream.Close();
return user;
}

/// <summary>
/// 泛型使用：把指定对象串转换指定字符串
/// </summary>
/// <param name="objects">需要转换的对象</param>
/// <param name="s">指定编码格式</param>
public static string ConverObjectToS<T>(T objects, Encoding s)
{
DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(T));
MemoryStream stream = new MemoryStream();
serializer.WriteObject(stream, objects);
return s.GetString(stream.ToArray());
}
}