Newtonsoft.Json程序包的引用
c#中使用json功能，需要Newtonsoft.Json程序包，可以通过NuGet程序包管理器搜索Newtonsoft.Json来安装，也可以在NuGet程序包管理器控制台下使用以下命令来安装：
install-package Newtonsoft.Json
然后引用NewTonSoft.Json命名空间。之后就可以将建立的对象转换为JSON字符串了。
如下创建一个类
public class Student
{
public int Id { get; set; }
public string Name { get; set; }
public string Sex { get; set; }
public string Description { get; set; }
}
生成对象并序列化为JSON字符串
List<Student> students = new List<Student>();
students.Add(new Student { Id = 1, Name = "张三", Sex = "男", Description = "班长" });
students.Add(new Student { Id = 2, Name = "李四", Sex = "女", Description = "小组长" });
students.Add(new Student { Id = 3, Name = "王五", Sex = "男", Description = "宣传委员" });
string studentsJson = JsonConvert.SerializeObject(students);
Console.WriteLine(studentsJson);
输出结果：
[{“Id”:1,”Name”:”张三”,”Sex”:”男”,”Description”:”班长”},{“Id”:2,”Name”:”李四”,”Sex”:”女”,”Description”:”小组长”},{“Id”:3,”Name”:”王五”,”Sex”:”男”,”Description”:”宣传委员”}]
有时我们可能不希望某些字段参与对象的JSON序列化，此时可以在该字段上使用[JsonIgnore]特性，对象被序列化后不会包含被忽略的字段
public class Student
{
public int Id { get; set; }
public string Name { get; set; }
[JsonIgnore]
public string Sex { get; set; }
public string Description { get; set; }
}
输出结果：
[{“Id”:1,”Name”:”张三”,”Description”:”班长”},{“Id”:2,”Name”:”李四”,”Description”:”小组长”},{“Id”:3,”Name”:”王五”,”Description”:”宣传委员”}]
有时我们可能想在对象序列化时更换字段的输出名称，譬如简化字段名称以缩短JSON字符串的长度，此时可使用[JsonProperty]特性标识字段
public class Student
{
public int Id { get; set; }
public string Name { get; set; }
[JsonIgnore]
public string Sex { get; set; }
[JsonProperty("Desc")]
public string Description { get; set; }
}
输出结果：
[{“Id”:1,”Name”:”张三”,”Desc”:”班长”},{“Id”:2,”Name”:”李四”,”Desc”:”小组长”},{“Id”:3,”Name”:”王五”,”Desc”:”宣传委员”}]
如果要将生成的JSON字符串以友好的格式化形式输出，可调用以下方法来转换
/// <summary>
/// 格式化JSON字符串
/// </summary>
/// <param name="str"></param>
/// <returns></returns>
private static string ConvertJsonString(string str)
{
JsonSerializer serializer = new JsonSerializer();
TextReader tr = new StringReader(str);
JsonTextReader jtr = new JsonTextReader(tr);
object obj = serializer.Deserialize(jtr);
if (obj != null)
{
StringWriter textWriter = new StringWriter();
JsonTextWriter jsonWriter = new JsonTextWriter(textWriter)
{
Formatting = Formatting.Indented,
Indentation = 4,
IndentChar = ' '
};
serializer.Serialize(jsonWriter, obj);
return textWriter.ToString();
}
else
{
return str;
}
}
于是上面的JSON字符串可改用格式化的形式输出
List<Student> students = new List<Student>();
students.Add(new Student { Id = 1, Name = "张三", Sex = "男", Description = "班长" });
students.Add(new Student { Id = 2, Name = "李四", Sex = "女", Description = "小组长" });
students.Add(new Student { Id = 3, Name = "王五", Sex = "男", Description = "宣传委员" });
//string studentsJson = JsonConvert.SerializeObject(students);
string studentsJson = ConvertJsonString(JsonConvert.SerializeObject(students));
Console.WriteLine(studentsJson);
输出结果：
[
{
“Id”: 1,
“Name”: “张三”,
“Desc”: “班长”
},
{
“Id”: 2,
“Name”: “李四”,
“Desc”: “小组长”
},
{
“Id”: 3,
“Name”: “王五”,
“Desc”: “宣传委员”
}
]
以下例子将构建的JSON字符串反序列化为对象，类的定义不要使用以上描述的两个附加特性
public class Student
{
public int Id { get; set; }
public string Name { get; set; }
//[JsonIgnore]
public string Sex { get; set; }
//[JsonProperty("Desc")]
public string Description { get; set; }
}
string inputJsonString = @"[
{ Id: 1, Name: '张三', Sex: '男', Description: '班长' },
{ Id: 2, Name: '李四', Sex: '女', Description: '小组长' },
{ Id: 3, Name: '王五', Sex: '男', Description: '宣传委员' }
]";
List<Student> objects = JsonConvert.DeserializeObject<List<Student>>(inputJsonString);
foreach (Student item in objects)
{
Console.WriteLine($"Id: {item.Id}, Name: {item.Name}, Sex: {item.Sex}, Description: {item.Description}");
}
输出结果：
Id: 1, Name: 张三, Sex: 男, Description: 班长
Id: 2, Name: 李四, Sex: 女, Description: 小组长
Id: 3, Name: 王五, Sex: 男, Description: 宣传委员
有时候我们可能需要序列化一个对象到字符串，或者反序列化字符串到对象，如对一个类进行封装传输或者存储。这首先需要使用特性[Serializable]将该对象类型标记为可序列化
// 标记类型可序列化
[Serializable]
public class Student
{
public int Id { get; set; }
public string Name { get; set; }
public string Sex { get; set; }
public string Description { get; set; }
}
一般对象的序列化和反序列化可以用以下两个方法来实现
/// <summary>
/// 序列化对象到字符串
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="obj"></param>
/// <returns></returns>
private static string Serialize<T>(T obj)
{
try
{
IFormatter formatter = new BinaryFormatter();
MemoryStream stream = new MemoryStream();
formatter.Serialize(stream, obj);
stream.Position = 0;
byte[] buffer = new byte[stream.Length];
stream.Read(buffer, 0, buffer.Length);
stream.Flush();
stream.Close();
return Convert.ToBase64String(buffer);
}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
}
/// <summary>
/// 反序列化字符串到对象
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="obj"></param>
/// <param name="str"></param>
/// <returns></returns>
public static T Deserialize<T>(T obj, string str)
{
try
{
obj = default(T);
IFormatter formatter = new BinaryFormatter();
byte[] buffer = Convert.FromBase64String(str);
MemoryStream stream = new MemoryStream(buffer);
obj = (T)formatter.Deserialize(stream);
stream.Flush();
stream.Close();
}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
return obj;
}
以下例子使用上述两个方法实现一般对象的序列化和反序列化
List<Student> students = new List<Student>();
students.Add(new Student { Id = 1, Name = "张三", Sex = "男", Description = "班长" });
students.Add(new Student { Id = 2, Name = "李四", Sex = "女", Description = "小组长" });
students.Add(new Student { Id = 3, Name = "王五", Sex = "男", Description = "宣传委员" });
string studentsString = Serialize(students);
Console.WriteLine($"序列化后的对象：\n{studentsString}");
List<Student> objects = new List<Student>();
objects = Deserialize(objects, studentsString);
Console.WriteLine("反序列化后的对象：");
foreach (Student item in objects)
{
Console.WriteLine($"Id: {item.Id}, Name: {item.Name}, Sex: {item.Sex}");
}
输出结果：
序列化后的对象：
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
反序列化后的对象：
Id: 1, Name: 张三, Sex: 男
Id: 2, Name: 李四, Sex: 女
Id: 3, Name: 王五, Sex: 男
