Newtonsoft.Json(Json.Net)学习笔记

落日映苍穹つ 2022-05-26 02:48 197阅读 0赞

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/][http_json.codeplex.com])。

下面是Json序列化和反序列化的简单封装：

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/// <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：

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/// <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：

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//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);

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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：\[\{"ID":"112","Name":"石子儿"\},\{"ID":"113","Name":"陈晨"\}\]。

[http_json.codeplex.com]: http://json.codeplex.com/
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