Json序列化和反序列化--Newtonsoft.Json

using Newtonsoft.Json;

写入文件，读取文件后，要及时释放FileStream ，StreamWriter StreamReader ，否则可能导致读写失败；

反序列化使用泛型方法，而不应使用as转换；

as可能导致转型失败；

JsonConvert.DeserializeObject<CStudent>(json)

string path = Application.StartupPath + @"\data.json";
        private void button2_Click(object sender, EventArgs e)
        {
            listBox1.Items.Add(path);
            CStudent student = new CStudent() { Name = "Tome", Sex = "male", Age = 18 };
            string json = JsonConvert.SerializeObject(student);

            using (FileStream stream = new FileStream(path, FileMode.OpenOrCreate))
            {
                StreamWriter sw = new StreamWriter(stream);

                sw.Write(json);
                sw.Dispose();
            }        }

 private void button3_Click(object sender, EventArgs e)
        {
            listBox1.Items.Clear();
            if (!File.Exists(path)) return;
            string json =null;
            using (FileStream stream = new FileStream(path, FileMode.Open))
            {
                StreamReader sr = new StreamReader(stream);
                json = sr.ReadToEnd();
                sr.Dispose();
            }
            listBox1.Items.Add("(json ==null)?" + (json == null));
            if (json ==null) return;
            var student3 = JsonConvert.DeserializeObject<CStudent>(json);

            listBox1.Items.Add(student3.Name);
            listBox1.Items.Add(student3.Sex);
            listBox1.Items.Add(student3.Age);
            listBox1.Items.Add("Say():"+student3.Say());
        }