你需要做两件事
1.从服务器加载您的Jason

var url = "https://www.sec.gov/files/company_tickers.json";
var client = new HttpClient();
var response = await client.GetAsync(url);
if (!response.IsSuccessStatusCode)
{
    Console.WriteLine($"Error: Can not connect with the server {response.StatusCode}");
    return;
}
var json = await response.Content.ReadAsStringAsync();

1.初始化JSON

• 将以下类添加到项目中

public class CompanyTickers
{
    [JsonPropertyName("cik_str")]
    public int Cik{ get; set; }
    [JsonPropertyName("ticker")]
    public string Ticker { get; set; } = string.Empty;
    [JsonPropertyName("title")]
    public string Title { get; set; } = string.Empty;
}

• 反序列化并使用结果

var companyTickers = JsonSerializer.Deserialize<Dictionary<int, CompanyTickers>>(json);
foreach(var company in companyTickers.Values)
{
    Console.WriteLine($"{company.Cik} {company.Ticker} {company.Title}");
}