为什么 C# BackgroundWorker 在导入文件时不报告进度？

Question

我是多线程的新手，需要帮助。我正在尝试在 C#（WPF 代码隐藏）中使用 BackgroundWorker，以便在通过 BinaryReader 导入文件时更新进度（通过标签内容）。问题是我需要完整的文件才能继续执行程序。因此，我需要知道它何时完成。

我正在尝试将主线程锁定在 while 循环内，直到布尔标志为真，但 ProgressChanged 和 RunWorkerCompleted 方法从未达到，并且在读取字节后主线程似乎被锁定在 while 循环内.你能建议在这种情况下最好的方法是什么吗？下面是我的代码。谢谢！

全球声明：

List<byte> storage_list = new List<byte>();
byte[] storage_byte_array = { (byte)0 };
bool Completed_Flag = false;

部分导入文件处理方法：

byte[] data = Read_File(directory_path);

foreach (byte b in data)
{
//etc

Read_File:

 byte[] Read_File(string directory_path)
 {
        Completed_Flag = false;
        BackgroundWorker worker = new BackgroundWorker();
        worker.WorkerReportsProgress = true;
        worker.DoWork += worker_DoWork;
        worker.ProgressChanged += worker_ProgressChanged;
        worker.RunWorkerCompleted += worker_RunWorkerCompleted;
        worker.RunWorkerAsync(directory_path);

        while (Completed_Flag == false)
        {
            System.Threading.Thread.Sleep(100);
        }
        return storage_byte_array;
   }

    void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        storage_byte_array = storage_list.ToArray();
        Completed_Flag = true;
    }

    void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        LBL.Content = e.ProgressPercentage;
        Console.WriteLine(e.ProgressPercentage);
    }

    void worker_DoWork(object sender, DoWorkEventArgs e)
    {
        string filename = (string)e.Argument;
        FileStream stream = File.OpenRead(@filename);
        var length = stream.Length;
        var position = 0;
        var buffer = new byte[1024];
        BinaryReader binReader = new BinaryReader(stream);

        while (position < length)
        {
            int store = binReader.Read(buffer, 0, buffer.Length);
            position = position + store;
            for (int i = 0; i < buffer.Length; i++)
            {
                storage_list.Add(buffer[i]);
            }
            int progressPercentage = Convert.ToInt32(((double)position / length) * 100);

            (sender as BackgroundWorker).ReportProgress(progressPercentage);
        }
        e.Result = storage_list;
    }

Answer 1

来自API：

"The call to the ReportProgress method is asynchronous and returns immediately. The ProgressChanged event handler executes on the thread that created the BackgroundWorker."

大概是因为您正在这里的主线程上忙着等待，

while (Completed_Flag == false)
{
   System.Threading.Thread.Sleep(100);
}

... 对 ReportProgress() 的调用永远没有机会执行。按照您设计它的方式，它基本上是在执行同步操作，那么为什么还要费心使用 BackgroundWorker？

为什么 C# BackgroundWorker 在导入文件时不报告进度？

Why is C# BackgroundWorker not reporting progress when importing a file?

c#

wpf

multithreading

backgroundworker