如何使用C#将字符串转换为预期格式的Json字符串

using Newtonsoft.Json;

public class Person
{
    public string Name { get; set; }
    public int Age { get; set; }
}

public string ConvertToJson()
{
    Person person = new Person { Name = "John", Age = 30 };
    string json = JsonConvert.SerializeObject(person);
    return json;
}

using System.Text.Json;

public class Person
{
    public string Name { get; set; }
    public int Age { get; set; }
}

public string ConvertToJson()
{
    Person person = new Person { Name = "John", Age = 30 };
    string json = JsonSerializer.Serialize(person);
    return json;
}

string json = JsonConvert.SerializeObject(person, Formatting.Indented);

var options = new JsonSerializerOptions { WriteIndented = true };
string json = JsonSerializer.Serialize(person, options);

public class Person
{
    public string Name { get; set; }
    [JsonIgnore]
    public Person Spouse { get; set; }
}

public class CustomConverter : JsonConverter<int>
{
    public override int Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        // 自定义读取逻辑
    }

    public override void Write(Utf8JsonWriter writer, int value, JsonSerializerOptions options)
    {
        // 自定义写入逻辑
    }
}

var options = new JsonSerializerOptions();
options.Converters.Add(new CustomConverter());
string json = JsonSerializer.Serialize(person, options);