在 MessageBox 问题上实现重试按钮功能 (C#)

Question

尝试编写一些代码来检索文件的文件路径，以便稍后在 ReadFile() 函数中使用它，但遇到了一些问题。

我的目标是实现一个 MessageBox，它输出带有重试和关闭按钮的错误消息，两者都可以正常工作。

当执行以下代码时，它只是循环 try 块并且永远不会进入 catch 块，这就是我希望它在不选择文件或单击 OpenFileDialog 上的取消时执行的操作。

下面是我目前正在使用的代码..

public static string GetFile() {
    MyLog.Write(@"Begin OpenFileDialog Process", LogFormat.Evaluate);
    var path = _lastFilePath != string.Empty ? _lastFilePath : GetBaseDirectory();
    if (path == null || !Directory.Exists(path))
        path = Assembly.GetExecutingAssembly().CodeBase;

    var dialog = new OpenFileDialog {
        InitialDirectory = path,
        Filter = @"Text|*.txt|All|*.*",
        RestoreDirectory = true
    };

    var result = DialogResult.Retry;
    while (result == DialogResult.Retry) {
        try {
            if (dialog.ShowDialog() != DialogResult.OK) {
                MyLog.Write(@"File Retrieval was Unsuccessful", LogFormat.Result);
            } else {
                MyLog.Write($"FilePath: {dialog.FileName}", LogFormat.Process);
                MyLog.Write(@"File Retrieval was Successful", LogFormat.Result);
                _lastFilePath = Path.GetDirectoryName(dialog.FileName);
                return dialog.FileName;
            }
        } catch when (result == DialogResult.Retry) {
            MyLog.Write("No File Selected", LogFormat.Error);
            result = MessageBox.Show(@"Please select a file..", @"No File Selected!", MessageBoxButtons.RetryCancel, MessageBoxIcon.Exclamation);
            if (result == DialogResult.Abort) throw;
            return null;
        }
    }
    return null;
}

我已尝试将代码调整为 similar question，但我很难理解为什么该逻辑在我的上下文中不起作用。

我做错了什么？

编辑： 使用以法莲的回答，我能够想出以下似乎可行的方法..

// USED TO RETRIEVE THE FILENAME IN A OPENFILEDIALOG
public static string GetFile() {
    MyLog.Write(@"Begin OpenFileDialog Process", LogFormat.Evaluate);
    var path = _lastFilePath != string.Empty ? _lastFilePath : GetBaseDirectory();
    if (path == null || !Directory.Exists(path))
        path = Assembly.GetExecutingAssembly().CodeBase;

    var dialog = new OpenFileDialog {
        InitialDirectory = path,
        Filter = @"Text|*.txt|All|*.*",
        RestoreDirectory = true
    };

    var result = DialogResult.Retry;
    while (result == DialogResult.Retry) {
        if (dialog.ShowDialog() != DialogResult.OK) {
            MyLog.Write(@"File Retrieval was Unsuccessful", LogFormat.Result);
            MyLog.Write("No File Selected", LogFormat.Error);
            result = MessageBox.Show(@"Please select a file..", @"No File Selected!", MessageBoxButtons.RetryCancel, MessageBoxIcon.Exclamation);
            if (result == DialogResult.Abort || result == DialogResult.Cancel) { break; }
            if (result == DialogResult.Retry) { return GetFile(); }
        }

        MyLog.Write($"FilePath: {dialog.FileName}", LogFormat.Process);
        MyLog.Write(@"File Retrieval was Successful", LogFormat.Result);
        _lastFilePath = Path.GetDirectoryName(dialog.FileName);
        return dialog.FileName;
    }
    return null;
}

Answer 1

您不需要在您的情况下执行 try-catch，因为当用户没有使用文件对话框选择任何内容时，不会引发或捕获任何异常。

试试：

while (result == DialogResult.Retry) {
        if (dialog.ShowDialog() != DialogResult.OK) {
                MyLog.Write(@"File Retrieval was Unsuccessful", LogFormat.Result);
                MyLog.Write("No File Selected", LogFormat.Error);
            result = MessageBox.Show(@"Please select a file..", @"No File Selected!", MessageBoxButtons.RetryCancel, MessageBoxIcon.Exclamation);
                if (result == DialogResult.Abort) throw;
                    return null;
            } else {
                MyLog.Write($"FilePath: {dialog.FileName}", LogFormat.Process);
                MyLog.Write(@"File Retrieval was Successful", LogFormat.Result);
                _lastFilePath = Path.GetDirectoryName(dialog.FileName);
                return dialog.FileName;
            }
    }