// 添加控制器并配置格式化器
var builder = WebApplication.CreateBuilder();
builder.Services.AddControllers(options =>
{
    options.Filters.Add<ContentTypeFilter>();
    options.ReturnHttpNotAcceptable = true; // 强制要求Accept头匹配
    // 添加 XML 格式化器
    options.InputFormatters.Add(new XmlSerializerInputFormatter(options));
    options.OutputFormatters.Add(new XmlSerializerOutputFormatter());
})
    .AddXmlSerializerFormatters()
    .AddJsonOptions(options =>
    {
        options.JsonSerializerOptions.Encoder = JavaScriptEncoder.Create(UnicodeRanges.All);
    });

添加筛选器

public class ContentTypeFilter: IResultFilter
{
    public void OnResultExecuting(ResultExecutingContext context)
    {
        if (context.Result is ObjectResult objectResult)
        {
            var requestContentType = context.HttpContext.Request.ContentType;
            if (requestContentType?.Contains("application/xml") == true)
            {
                objectResult.ContentTypes.Clear();
                objectResult.ContentTypes.Add("application/xml");
            }
            else // 默认或JSON
            {
                objectResult.ContentTypes.Clear();
                objectResult.ContentTypes.Add("application/json");
            }
        }
    }

    public void OnResultExecuted(ResultExecutedContext context) { }
}