C#如何Json转字符串；字符串转Json；Newtonsoft.Json(Json.Net)

 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"}]。

JsonHelper下载