How to use StreamWriter.WriteAsync and catch exceptions?

问题

I have simple function to write files.

public static void WriteFile(string filename, string text)
{
    StreamWriter file = new StreamWriter(filename);
    try
    {
        file.Write(text);
    }
    catch (System.UnauthorizedAccessException)
    {
        MessageBox.Show("You have no write permission in that folder.");
    }
    catch (System.Exception e)
    {
        MessageBox.Show(e.Message);
    }

    file.Close();
}

How can I convert my code to use StreamWriter.WriteAsync with try-catch?

回答1:

async public static void WriteFile(string filename, string text)
{
    StreamWriter file = null;
    try
    {
        file = new StreamWriter(filename);
        await file.WriteAsync(text);
    }
    catch (System.UnauthorizedAccessException)
    {
        MessageBox.Show("You have no write permission in that folder.");
    }
    catch (System.Exception e)
    {
        MessageBox.Show(e.Message);
    }
    finally
    {
        if (file != null) file.Close();
    }
}

来源：https://stackoverflow.com/questions/18943154/how-to-use-streamwriter-writeasync-and-catch-exceptions