如何使用 C# WebClient 从 JSON URL 请求特定对象

Question

以下代码返回整个JSON对象，但我需要过滤到某个特定的对象，例如我只需要获取"layers"或tiltle你能告诉我如何做到这一点是C#吗？

我必须为此创建一个HttpWebRequest对象吗？ 如果是这样，我应该将请求的数据传递到哪里？

using (WebClient wc = new WebClient())
   {
    var json = wc.DownloadString("https://sampleserver6.arcgisonline.com/arcgis/rest/services/Water_Network/FeatureServer?f=pjson");
    Console.WriteLine(json);
   }

我已经试过了，但它也返回了所有内容

class Program
{
    private const string URL = "https://sampleserver6.arcgisonline.com/arcgis/rest/services/Water_Network/FeatureServer?f=pjson";
    private const string DATA = @"{{""layers"":""Layers""}}";
    static void Main(string[] args)
    {
       CreateObject();
    }
    private static void CreateObject()
    {
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(URL);
        request.Method = "POST";
        request.ContentType = "application/json";
        request.ContentLength = DATA.Length;
        using (Stream webStream = request.GetRequestStream())
        using (StreamWriter requestWriter = new StreamWriter(webStream, System.Text.Encoding.ASCII))
        {
            requestWriter.Write(DATA);
        }
        try
        {
            WebResponse webResponse = request.GetResponse();
            using (Stream webStream = webResponse.GetResponseStream())
            {
                if (webStream != null)
                {
                    using (StreamReader responseReader = new StreamReader(webStream))
                    {
                        string response = responseReader.ReadToEnd();
                        Console.WriteLine(response);
                        Console.ReadLine();
                    }
                }
            }
        }
        catch (Exception e)
        {
            Console.WriteLine("-----------------");
            Console.WriteLine(e.Message);
            Console.ReadLine();
        }
    }
}

Answer 1

如果您需要与layers数组对象相关的信息，则可以使用以下代码

 using (var wc = new WebClient())
 {
     string json = wc.DownloadString("https://sampleserver6.arcgisonline.com/arcgis/rest/services/Water_Network/FeatureServer?f=pjson");
     dynamic data = Json.Decode(json);
     Console.WriteLine(data.layers[0].id);
     Console.WriteLine(data.layers[0].name);
     Console.WriteLine(data.documentInfo.Title);
 }