正确中止或取消PostAsync [英] Properly Abort or Cancel PostAsync
本文介绍了正确中止或取消PostAsync的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
使用HttpClient时是否有保证取消帖子的方法?我目前有一个呼叫PostAsync,我正在尝试使用cancelleToken取消,但看来它实际上并未中止/停止该操作。我仍然可以看到我上传的图像已正确发布。
Is there a guaranteed way to cancel a post when using HttpClient? I currently have a call do PostAsync that I am attempting to cancel using a cancellationToken, but it appears that it does not actually abort/stop the operation. I still can see that the image I am uploading is posted properly.
我在这里做错了吗,还是HttpClient直到上载之后才处理取消令牌?
Am I doing something wrong here or is it possible that HttpClient is not processing the cancellation token until after the upload?
var sc = new StreamContent(uploadFile.Data);
content.Add(sc, uploadFile.FieldName, uploadFile.FileName);
var request = new HttpRequestMessage
{
RequestUri = new Uri(ApiImageUrlUpload),
Content = content
};
request.Headers.TryAddWithoutValidation("User-Agent", _sessionManager.UserAgent);
request.Headers.TransferEncodingChunked = true;
using(cancellationToken.Register(() => httpClient.CancelPendingRequests()))
httpResponse = await HttpClient.PostAsync(new Uri(ApiImageUrlUpload), content, cancellationToken);
推荐答案
尝试以下代码示例
public partial class LoginForm : MaterialForm
{
static NLog.Logger logger = LogManager.GetLogger("LoginForm");
HttpClient client;
HttpResponseMessage response;
public LoginForm()
{
InitializeComponent();
materialLabelErrMessage.Visible = false;
}
#region GUI events
private void BntCancel_Click(object sender, EventArgs e)
{
CancelLogin();
Close();
}
private void BtnOK_Click(object sender, EventArgs e)
{
Login();
}
private void TextBoxPassword_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
Login();
}
}
private void TextBoxUsername_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Enter)
{
Login();
}
}
#endregion
#region Keyboard Helpers
protected override bool ProcessDialogKey(Keys keyData)
{
if (Form.ModifierKeys == Keys.None && keyData == Keys.Escape)
{
CancelLogin();
Close();
return true;
}
return base.ProcessDialogKey(keyData);
}
#endregion
async void Login()
{
try
{
pbLogin.Visible = true;
btnOK.Enabled = false;
materialLabelErrMessage.Text = string.Empty;
materialLabelErrMessage.Visible = false;
client = new HttpClient();
var user = new User() { Username = textBoxUsername.Text.Trim(), Password = StringUtils.Crypt(textBoxPassword.Text.Trim()) };
var url = Properties.Settings.Default.ServerBaseUrl + @"/api/account/VerifyUserNamePassword";
response = await client.PostAsync(url, user.AsJson());
if (response.IsSuccessStatusCode) // Check the response StatusCode
{
var serSettings = new JsonSerializerSettings() { TypeNameHandling = TypeNameHandling.All };
string responseBody = await response.Content.ReadAsStringAsync();
var loggedUser = JsonConvert.DeserializeObject<User>(responseBody, serSettings);
if (loggedUser.IsLogged == false && loggedUser.UserId == Guid.Empty)
{
logger.Warn(Properties.Resources.LOGINUsernameOrPasswordWrong + " Username:" + user.Username);
BeginInvoke((Action)(() =>
{
materialLabelErrMessage.Text = Properties.Resources.LOGINUsernameOrPasswordWrong;
materialLabelErrMessage.Visible = true;
pbLogin.Visible = false;
btnOK.Enabled = true;
}));
}
else
{
logger.Info(Properties.Resources.LOGINPassed + " Username:" + user.Username);
BeginInvoke((Action)(() =>
{
materialLabelErrMessage.Text = string.Empty;
materialLabelErrMessage.Visible = false;
Program.UserInfo = loggedUser;
DialogResult = DialogResult.OK;
pbLogin.Visible = false;
}));
}
}
else if (response.StatusCode == HttpStatusCode.Forbidden)
{
pbLogin.Visible = false;
btnOK.Enabled = true;
materialLabelErrMessage.Text = Properties.Resources.LOGINUsernameOrPasswordWrong;
materialLabelErrMessage.Visible = true;
logger.Warn(Properties.Resources.LOGINUsernameOrPasswordWrong + " Username:" + user.Username);
}
else
{
pbLogin.Visible = false;
btnOK.Enabled = true;
materialLabelErrMessage.Text = Properties.Resources.LOGINCannotConnectToServer;
materialLabelErrMessage.Visible = true;
logger.Error("Reason: " + response.ReasonPhrase + " Message: " + response.RequestMessage + " Username:" + user.Username);
}
}
catch (ObjectDisposedException ex)
{
logger.Error("Login has been canceled. " + ex.Message);
pbLogin.Visible = false;
btnOK.Enabled = true;
}
catch (Exception ex)
{
logger.Error(Properties.Resources.LOGINUsernameOrPasswordWrong + " " + ex.Message);
pbLogin.Visible = false;
btnOK.Enabled = true;
}
}
void CancelLogin()
{
if (client != null)
{
client.CancelPendingRequests();
client = null;
}
}
}
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