使用System.Text.Json反序列化为不区分大小写的字典

using System;
using System.Collections.Generic;
using System.Text.Json;
using System.Text.Json.Serialization;

public class DictionaryCaseInsensitiveConverter<TValue> : JsonConverter<Dictionary<string, TValue>>
{
    public override Dictionary<string, TValue> Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        var dictionary = new Dictionary<string, TValue>(StringComparer.OrdinalIgnoreCase);
        var jsonDocument = JsonDocument.ParseValue(ref reader);

        foreach (var property in jsonDocument.RootElement.EnumerateObject())
        {
            var key = property.Name;
            var value = JsonSerializer.Deserialize<TValue>(property.Value.GetRawText(), options);
            dictionary[key] = value;
        }

        return dictionary;
    }

    public override void Write(Utf8JsonWriter writer, Dictionary<string, TValue> value, JsonSerializerOptions options)
    {
        writer.WriteStartObject();

        foreach (var pair in value)
        {
            writer.WritePropertyName(pair.Key);
            JsonSerializer.Serialize(writer, pair.Value, options);
        }

        writer.WriteEndObject();
    }
}

using System;
using System.Collections.Generic;
using System.Text.Json;

public class Program
{
    public static void Main()
    {
        var jsonString = "{\"Key1\": \"Value1\", \"key2\": \"Value2\", \"KEY3\": \"Value3\"}";

        var options = new JsonSerializerOptions();
        options.Converters.Add(new DictionaryCaseInsensitiveConverter<string>());

        var dictionary = JsonSerializer.Deserialize<Dictionary<string, string>>(jsonString, options);

        foreach (var pair in dictionary)
        {
            Console.WriteLine($"{pair.Key}: {pair.Value}");
        }
    }
}

Key1: Value1
key2: Value2
KEY3: Value3