Newtonsoft.Json(Json.Net)學習筆記

  Newtonsoft.Json，一款.NET中開源的Json序列化和反序列化類庫(下載地址http://json.codeplex.com/)。

         下面是Json序列化和反序列化的簡單封裝：

/// <summary>
    /// Json幫助類
    /// </summary>
    public class JsonHelper
    {
        /// <summary>
        /// 將對象序列化為JSON格式
        /// </summary>
        /// <param name="o">對象</param>
        /// <returns>json字符串</returns>
        public static string SerializeObject(object o)
        {
            string json = JsonConvert.SerializeObject(o);
            return json;
        }

        /// <summary>
        /// 解析JSON字符串生成對象實體
        /// </summary>
        /// <typeparam name="T">對象類型</typeparam>
        /// <param name="json">json字符串(eg.{"ID":"112","Name":"石子兒"})</param>
        /// <returns>對象實體</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數組生成對象實體集合
        /// </summary>
        /// <typeparam name="T">對象類型</typeparam>
        /// <param name="json">json數組字符串(eg.[{"ID":"112","Name":"石子兒"}])</param>
        /// <returns>對象實體集合</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到給定的匿名對象.
        /// </summary>
        /// <typeparam name="T">匿名對象類型</typeparam>
        /// <param name="json">json字符串</param>
        /// <param name="anonymousTypeObject">匿名對象</param>
        /// <returns>匿名對象</returns>
        public static T DeserializeAnonymousType<T>(string json, T anonymousTypeObject)
        {
            T t = JsonConvert.DeserializeAnonymousType(json, anonymousTypeObject);
            return t;
        }
    }

　　為進一步理解Newtonsoft，寫了一些測試的例子：

/// <summary>
    /// Json測試
    /// </summary>
    public class JsonTest : IRun
    {
        public void Run()
        {
            Student sdudent = new Student();
            sdudent.ID = 1;
            sdudent.Name = "陳晨";
            sdudent.NickName = "石子兒";
            sdudent.Class = new Class() { Name = "CS0216", ID = 0216 };

            //實體序列化和反序列化
            string json1 = JsonHelper.SerializeObject(sdudent);
            //json1 : {"ID":1,"Name":"陳晨","NickName":"石子兒","Class":{"ID":216,"Name":"CS0216"}}
            Student sdudent1 = JsonHelper.DeserializeJsonToObject<Student>(json1);

            //實體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":"陳晨","NickName":"石子兒","Class":{"ID":216,"Name":"CS0216"}},{"ID":1,"Name":"陳晨","NickName":"石子兒","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"] = "戰三";
            dr["NickName"] = "小三";
            dt.Rows.Add(dr);
            string json3 = JsonHelper.SerializeObject(dt);
            //json3 : [{"ID":112,"Name":"戰三","NickName":"小三"}]
            DataTable sdudentDt3 = JsonHelper.DeserializeJsonToObject<DataTable>(json3);
            List<Student> sdudentList3 = JsonHelper.DeserializeJsonToList<Student>(json3);

            //驗證對象和數組
            Student sdudent4 = JsonHelper.DeserializeJsonToObject<Student>("{\"ID\":\"112\",\"Name\":\"石子兒\"}");
            List<Student> sdudentList4 = JsonHelper.DeserializeJsonToList<Student>("[{\"ID\":\"112\",\"Name\":\"石子兒\"}]");

            //匿名對象解析
            var tempEntity = new { ID = 0, Name = string.Empty };
            string json5 = JsonHelper.SerializeObject(tempEntity);
            //json5 : {"ID":0,"Name":""}
            tempEntity = JsonHelper.DeserializeAnonymousType("{\"ID\":\"112\",\"Name\":\"石子兒\"}", tempEntity);
            var tempStudent = new Student();
            tempStudent = JsonHelper.DeserializeAnonymousType("{\"ID\":\"112\",\"Name\":\"石子兒\"}", tempStudent);

            Console.Read();
        }

    }

    /// <summary>
    /// 學生信息實體
    /// </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>
    /// 學生班級實體
    /// </summary>
    public class Class
    {
        public int ID { get; set; }
        public string Name { get; set; }
    }

 

         使用Json幫助類時，有兩點需要注意下：

         1. 通常使用調用實體序列化SerializeObject()和反序列化DeserializeJsonToObject()兩個方法就可以了。但有些情況下我們解析json字符串時，可能沒有對應的實體類型（或者說不想添加對應的實體類），這時候可以用匿名對象解析方法DeserializeAnonymousType()，方便快捷，對應代碼如下：

//匿名對象解析
            var tempEntity = new { ID = 0, Name = string.Empty };
            string json5 = JsonHelper.SerializeObject(tempEntity);
            //json5 : {"ID":0,"Name":""}
            tempEntity = JsonHelper.DeserializeAnonymousType("{\"ID\":\"112\",\"Name\":\"石子兒\"}", tempEntity);
            Console.WriteLine(tempEntity.ID + ":" + tempEntity.Name);

         2. Json的兩種結構數組和對象解析時略有不同。Json對象一般轉換成實體，Json數組一般轉換成實體集合。代碼如下：

//驗證對象和數組
            Student sdudent4 = JsonHelper.DeserializeJsonToObject<Student>("{\"ID\":\"112\",\"Name\":\"石子兒\"}");
            List<Student> sdudentList4 = JsonHelper.DeserializeJsonToList<Student>("[{\"ID\":\"112\",\"Name\":\"石子兒\"}]");

         簡單解釋下Json對象和數組的含義：

         對象是以“{”（左括號）開始，“}”（右括號）結束。每個“名稱”后跟一個“:”（冒號）；“‘名稱/值’ 對”之間運用 “,”（逗號）分隔。名稱用引號括起來；值如果是字符串則必須用括號，數值型則不須要。例如：{"ID":"112","Name":"石子兒"}。

         數組是值（value）的有序集合。一個數組以“[”（左中括號）開始，“]”（右中括號）結束。值之間運用 “,”（逗號）分隔。例如：[{"ID":"112","Name":"石子兒"},{"ID":"113","Name":"陳晨"}]。