c# - 在后台开始获取响应

Question

我有一个主页，它从网络其他信息中获取新闻和 n 后台加载：

BackgroundWorker bw = new BackgroundWorker();
        bw.WorkerSupportsCancellation = true;
        bw.DoWork += new DoWorkEventHandler(GetContacts);
        bw.RunWorkerAsync();

private void GetContacts(object sender, DoWorkEventArgs e)
    {
        BackgroundWorker bw = new BackgroundWorker();
        bw.WorkerSupportsCancellation = true;
        bw.DoWork += new DoWorkEventHandler(getServiceContactData);
        BackgroundWorker worker = sender as BackgroundWorker;
        if ((worker.CancellationPending == true))
        {
            e.Cancel = true;
        }
        long cont = 0;

       //This made to pause a thread for a long time

        do
        {
            cont++;
        }
        while (cont != 999999999);
        getServiceContactData();
}

private void getServiceContactData()
    {
        HttpWebRequest request = HttpWebRequest.CreateHttp(GS.BACKEND_HOST + "sfbsfb");
        request.BeginGetResponse(new AsyncCallback(HandleResponseContacts), request);
    }

private void HandleResponseContacts(IAsyncResult result)
    {
        HttpWebRequest request = result.AsyncState as HttpWebRequest;
        if (request != null)
        {
            using (WebResponse response = request.EndGetResponse(result))
            {
                using (StreamReader reader = new StreamReader(response.GetResponseStream()))
                {
                    string JSON = reader.ReadToEnd();
                    if (JSON == "")
                    {
                        NoItems = true;
                    }
                    IsolatedStorage IS = new IsolatedStorage();
                    IS.Save("ContactsStorage.txt", JSON);
                    IS.SaveContactsRetrieveDate(DateTime.Now.ToString("dd.MM.yyyy"));
                    Deployment.Current.Dispatcher.BeginInvoke(() =>
                    {
                        //MessageBox.Show("got");
                    });
                }
            }
        }

    }

在联系人页面上有：

string contactsRetriveDate = "";
        DateTime a;
        string now = DateTime.Now.ToString("MM/dd/yyyy");
        string then = "";
        do
        {
            contactsRetriveDate = IS.ReadContactsRetriveDate();
            if (contactsRetriveDate != "")
            {
                a = DateTime.ParseExact(contactsRetriveDate, "dd.MM.yyyy", System.Globalization.CultureInfo.InvariantCulture);
                a.ToString("MM/dd/yyyy");
            }
        }
        while(then!=now);
        MessageBox.Show("Estj");

此代码检查联系人的最后更新日期，当 now = then 时显示消息框。

目的：

目的是在后台下载联系人数据，以便在联系人页面上没有太多时间等待......换句话说，在打开联系人页面之前开始获取联系人数据。

但是代码不做HandleResponseContacts，当我导航到另一个页面时它只是不进入那个函数。

Answer 1

发现我错了。

错误的方法是让联系人页面上的主线程忙：

我应该这样做：

string contactsRetriveDate = "";
    DateTime a;
    string now = DateTime.Now.ToString("MM/dd/yyyy");
    string then = "";
    do
    {
        contactsRetriveDate = IS.ReadContactsRetriveDate();
        if (contactsRetriveDate != "")
        {
            a = DateTime.ParseExact(contactsRetriveDate, "dd.MM.yyyy", System.Globalization.CultureInfo.InvariantCulture);
            a.ToString("MM/dd/yyyy");
        }
    }
    while(then!=now);
    MessageBox.Show("Estj");

在后台工作人员中。

代码不起作用，因为主线程很忙。