HttpClient在网络恢复时连接到azure服务器时抛出错误-无法连接到远程服务器

Question

从WPF控件中托管的httpclient向azure服务器发出查询，azure服务器将结果发送回WPF控件。当禁用Internet连接并执行postasync查询时，将抛出httprequestexception。当互联网连接恢复并进行postaysnc查询时，post async工作正常，如果我再次禁用互联网连接并使post async抛出异常。一旦重新建立了internet连接，postasync就会抛出httprequest异常。如何解决这个问题。

var httpContent = new StringContent(value, Encoding.UTF8, "application/json");
var queryUri = new Uri(httpClient.BaseAddress, "content/resultvalue");
var response = await httpClient.PostAsync(queryUri, httpContent);
response.EnsureSuccessStatusCode();
var resultJson = await response.Content.ReadAsStringAsync();
var result = JsonConvert.DeserializeObject<Result>(resultJson);

Answer 1

这是预期的行为。如果它无法连接到服务器，则会抛出异常。在Exception Handling标题下的HttpClient.PostAsync文档中对此进行了描述。

如果需要捕获异常，则将其放在try/catch块中，并对该异常执行一些操作。

var httpContent = new StringContent(value, Encoding.UTF8, "application/json");
var queryUri = new Uri(httpClient.BaseAddress, "content/resultvalue");
try {
    var response = await httpClient.PostAsync(queryUri, httpContent);
    response.EnsureSuccessStatusCode();
    var resultJson = await response.Content.ReadAsStringAsync();
    var result = JsonConvert.DeserializeObject<Result>(resultJson);
} catch (Exception e) {
    //report the exception to the user
}