使用.NET通过HTTP发送base64编码的字符串

using System;
using System.Net.Http;
using System.Text;

class Program
{
    static async System.Threading.Tasks.Task Main(string[] args)
    {
        // 要发送的base64编码的字符串
        string base64String = "SGVsbG8gd29ybGQh";

        // 创建HttpClient实例
        using (HttpClient client = new HttpClient())
        {
            // 构造HTTP请求的内容
            var content = new StringContent(base64String, Encoding.UTF8, "text/plain");

            // 发送POST请求
            HttpResponseMessage response = await client.PostAsync("http://example.com/api/endpoint", content);

            // 检查响应状态码
            if (response.IsSuccessStatusCode)
            {
                // 处理成功响应
                string responseContent = await response.Content.ReadAsStringAsync();
                Console.WriteLine("成功响应：" + responseContent);
            }
            else
            {
                // 处理错误响应
                Console.WriteLine("错误响应：" + response.StatusCode);
            }
        }
    }
}