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"}]。