C＃如何在嘗試url.GetStringAsync null時重試？

Question

我想問一下如何重試是否await url.GetStringAsync獲取取消任務？

ServicePointManager.Expect100Continue = true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
var httpclient = new HttpClient();
var html = await httpclient.GetStringAsync(url);

Answer 1

如果您希望在上面的代碼中這樣做（而不是使用HttpResponse對象），則可以執行以下操作

ServicePointManager.Expect100Continue = true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
var httpclient = new HttpClient();
int retries = 5;
int count = 0;
var html = await httpclient.GetStringAsync(url);

while(String.IsNullOrEmpty(html) && count++ < retries) {
    var html = await httpclient.GetStringAsync(url); }

if(String.IsNullOrEmpty(html)) {
    throw new Exception("Could not contact the server"); }