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C＃2008C＃异常处理类
我开发了下面的类。我必须从Web服务器获取余额。一旦完成，它会回调我的主应用程序的结果。
但是，有时Web服务器出于某种未知原因失败。可能是大量的流量或其他东西。但是，我没有在我的课上实施任何异常处理。由于使用此应用程序处理异常。
但是，客户端已经确认，当Web服务器确实失败时，它会显示未处理的异常对话框。然后他们必须点击继续继续使用我的应用程序。
所以下面我不确定是否应该在我的类中实现异常处理。不过，我很困惑，为什么这个例外没有在我的应用程序中被捕获，如下所示。
的任何建议非常感谢，或者如果你看到别的错误，
private void OnGetBalanceCompleted(object sender, SIPPhoneLibraryEventArgs e)
{
try
{
//If the balance starts with 'null' there has been an error trying to get the balance.
if (e.Balance.StartsWith("null"))
{
statusDisplay1.CurrentBalance = CATWinSIP_MsgStrings.BalanceError;
}
else
{
// Display the current balance and round to 2 decimal places.
statusDisplay1.CurrentBalance = Math.Round(Convert.ToDecimal(e.Balance), 2).ToString();
//If the balance is zero display in the status message
if (decimal.Parse(e.Balance) == 0)
{
this.statusDisplay1.CallStatus = "Zero Balance";
}
}
//Remove the event as no longer needed
siplibrary.GetBalanceCompletedEvent -= new EventHandler<SIPPhoneLibraryEventArgs>(OnGetBalanceCompleted);
}
catch (WebException ex)
{
MessageBox.Show(ex.Message);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
//Control library for all importing functions
public class Balance : IDisposable
{
//Constructor
WebClient wc;
public Balance()
{
using (wc = new WebClient())
{
//Create event handler for the progress changed and download completed events
wc.DownloadProgressChanged += new DownloadProgressChangedEventHandler(wc_DownloadProgressChanged);
wc.DownloadStringCompleted += new DownloadStringCompletedEventHandler(wc_DownloadStringCompleted);
}
}
~Balance()
{
this.Dispose(false);
}
//Event handler and the method that handlers the event
public EventHandler<SIPPhoneLibraryEventArgs> GetBalanceCompletedEvent;
//The method that raises the event
public void OnGetBalanceCompleted(SIPPhoneLibraryEventArgs e)
{
if (GetBalanceCompletedEvent != null)
{
GetBalanceCompletedEvent(this, e);
}
}
//Get the current balance for the user that is logged in.
//If the balance returned from the server is NULL display error to the user.
//Null could occur if the DB has been stopped or the server is down.
public void GetBalance(string sipUsername)
{
//Remove the underscore (_) from the username, as this is not needed to get the balance.
sipUsername = sipUsername.Remove(0, 1);
string strURL = string.Format("http://xxx.xxx.xx.xx:xx/voipbilling/servlet/advcomm.voipbilling.GetBalance?CustomerID={0}", sipUsername);
//Download only when the webclient is not busy.
if (!wc.IsBusy)
{
// Sleep for 1/2 second to give the server time to update the balance.
System.Threading.Thread.Sleep(500);
// Download the current balance.
wc.DownloadStringAsync(new Uri(strURL));
}
else
{
System.Windows.Forms.MessageBox.Show("Busy please try again");
}
}
//return and display the balance after the download has fully completed
void wc_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
//Pass the result to the event handler
this.OnGetBalanceCompleted(new SIPPhoneLibraryEventArgs(e.Result));
}
//Progress state of balance.
void wc_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
{
//Write the details to the screen.
Console.WriteLine(e.TotalBytesToReceive);
Console.WriteLine(e.BytesReceived);
Console.WriteLine(e.ProgressPercentage);
}
//Dispose of the balance object
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
//Remove the event handlers
private bool isDisposed = false;
private void Dispose(bool disposing)
{
if (!this.isDisposed)
{
if (disposing)
{
wc.DownloadProgressChanged -= new DownloadProgressChangedEventHandler(wc_DownloadProgressChanged);
wc.DownloadStringCompleted -= new DownloadStringCompletedEventHandler(wc_DownloadStringCompleted);
wc.Dispose();
}
isDisposed = true;
}
}
}