C# - 如何进行HTTP调用

using System;
using System.Net.Http;
using System.Threading.Tasks;

class Program
{
    static async Task Main(string[] args)
    {
        using HttpClient client = new HttpClient();
        string url = "https://api.example.com/data";
        HttpResponseMessage response = await client.GetAsync(url);
        if (response.IsSuccessStatusCode)
        {
            string content = await response.Content.ReadAsStringAsync();
            Console.WriteLine(content);
        }
        else
        {
            Console.WriteLine($"Error: {response.StatusCode}");
        }
    }
}

using System;
using System.Net.Http;
using System.Threading.Tasks;
using System.Text.Json;

class Program
{
    static async Task Main(string[] args)
    {
        using HttpClient client = new HttpClient();
        string url = "https://api.example.com/data";
        var data = new { key1 = "value1", key2 = "value2" };
        string json = JsonSerializer.Serialize(data);
        HttpContent content = new StringContent(json, System.Text.Encoding.UTF8, "application/json");
        HttpResponseMessage response = await client.PostAsync(url, content);
        if (response.IsSuccessStatusCode)
        {
            string result = await response.Content.ReadAsStringAsync();
            Console.WriteLine(result);
        }
        else
        {
            Console.WriteLine($"Error: {response.StatusCode}");
        }
    }
}