EventArgs 數據使用情況

Question

我有三個類， FileManagerClass包含兩個事件，即EventHandler<FileTransferEventArgs> FileMove和EventHandler<FileTransferEventArgs> FileMoveError 。

然后，我有一個名為FileTransferEventArg的自定義EventArgs class，它繼承自基本EventArgs class。 我有第三個 class 稱為FolderDirectoryModel然后偵聽要引發的事件並使用OnFileMove(object sender, FileTransferEventArg arg)或OnFileMoveError(object sender, FileTransferEventArg arg)對其進行響應。

總的來說，它看起來像這樣：

class FileTransferManager
{
    public event EventHandler<FileTransferEventArgs> FileMove;
    public event EventHandler<FileTransferEventArgs> FileMoveError;
}

public class FileTransferEventArgs : EventArgs
{
    string FileName { get; set; }
    string Message { get; set; }

    internal FileTransferEventArgs(FileModel file, string message)
    {
        this.FileName = file.FileName;
        this.Message = message;
    }
}

public class FolderDirectoryModel
{
    void TransferFile(FileModel toBeTransfered, string destinationPath)
    {
        if (!File.Exists(toBeTransfered.FilePath))
        {
            File.Move(toBeTransfered.FilePath, destinationPath);
            FileTransferEvents.FileTransferManager TransferAgent = new FileTransferEvents.FileTransferManager();
            TransferAgent.FileMove += new EventHandler<FileTransferEventArgs>(OnFileMove);                
        }
        else
        {
            FileTransferEvents.FileTransferManager TransferAgent = new FileTransferEvents.FileTransferManager();
            TransferAgent.FileMoveError += new EventHandler<FileTransferEventArgs>(OnFileMoveError);
        }
    }

    //Handler Methods
    private void OnFileMoveError(object sender, FileTransferEventArgs args)
    {
        //what i want to happen

        MessageBox.Show($"File {args.FileName} has not been moved succefully to {args.FilePath} because of....");
    }

    private void OnFileMove(object sender, FileTransferEventArgs args)
    {
        //what i want to happen
        MessageBox.Show($"File {args.FileName} has been moved successfully to {args.FilePath}
    }
}

我的問題是我想使用FileTransferEventArgs class 中的屬性來顯示移動的文件名，無論它是否成功，並提供將在消息屬性中的原因。

但是，當我把所有東西都連接起來時，我無法查看傳遞的數據。 我不確定我是否不正確地使用了這些事件，或者我正在嘗試做一些不可能的事情。

Answer 1

FileMove和FileMoveError事件必須放在FolderDirectoryModel class 中。

事件在同一個 class 中觸發。 使用Invoke方法。

public class FileTransferEventArgs : EventArgs
{
    public string FileName { get; }
    public string FilePath { get; }
    public string Message { get; }

    internal FileTransferEventArgs(FileModel file, string message)
    {
        FileName = file.FileName;
        FilePath = file.FilePath;
        Message = message;
    }
}

public class FileModel
{
    public string FileName { get; set; }
    public string FilePath { get; set; }
}

public class FolderDirectoryModel
{
    public event EventHandler<FileTransferEventArgs> FileMove;
    public event EventHandler<FileTransferEventArgs> FileMoveError;

    public void TransferFile(FileModel fileModel, string destinationPath)
    {
        if (!File.Exists(fileModel.FilePath))
        {
            File.Move(fileModel.FilePath, destinationPath);
            var fileTransferEventArgs = new FileTransferEventArgs(fileModel, "Success");
            FileMove?.Invoke(this, fileTransferEventArgs);
        }
        else
        {
            var fileTransferEventArgs = new FileTransferEventArgs(fileModel, "Cannot move");
            FileMoveError?.Invoke(this, fileTransferEventArgs);
        }
    }
}

用法

var fileModel = new FileModel { FileName = "name", FilePath = "path" };

var folderDirectoryModel = new FolderDirectoryModel();
folderDirectoryModel.FileMove += FolderDirectoryModel_FileMove;
folderDirectoryModel.FileMoveError += FolderDirectoryModel_FileMoveError;

folderDirectoryModel.TransferFile(fileModel, "destPath");

void FolderDirectoryModel_FileMove(object sender, FileTransferEventArgs args)
{
    MessageBox.Show($"File {args.FileName} has been moved successfully to {args.FilePath}");
}

void FolderDirectoryModel_FileMoveError(object sender, FileTransferEventArgs args)
{
    MessageBox.Show($"File {args.FileName} has not been moved to {args.FilePath} because of {args.Message}");
}

事件處理程序位於創建和使用FolderDirectoryModel實例的同一代碼中。