使用webrequest返回API失败

try
{
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://example.com/api");
    using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
    {
        // 处理响应
    }
}
catch (WebException ex)
{
    if (ex.Status == WebExceptionStatus.Timeout)
    {
        Console.WriteLine("请求超时");
    }
    else if (ex.Status == WebExceptionStatus.NameResolutionFailure)
    {
        Console.WriteLine("域名解析失败");
    }
    else
    {
        Console.WriteLine("网络错误: " + ex.Message);
    }
}

HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://example.com/api");
request.Credentials = new NetworkCredential("username", "password");

HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://example.com/api");
request.Method = "POST";
request.ContentType = "application/json";
string json = "{\"key\":\"value\"}";
byte[] data = Encoding.UTF8.GetBytes(json);
request.ContentLength = data.Length;
using (Stream stream = request.GetRequestStream())
{
    stream.Write(data, 0, data.Length);
}

try
{
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://example.com/api");
    using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
    {
        if (response.StatusCode == HttpStatusCode.InternalServerError)
        {
            Console.WriteLine("服务器内部错误");
        }
        else
        {
            // 处理正常响应
        }
    }
}
catch (WebException ex)
{
    Console.WriteLine("请求失败: " + ex.Message);
}