向背景工作者发送参数？

Question

假设我想将一个int参数发送给后台工作者,如何实现呢？

private void worker_DoWork(object sender, DoWorkEventArgs e) {

}

我知道什么时候这是worker.RunWorkerAsync();,我不明白如何在worker_DoWork中定义它应该采用int参数.

Answer 1

你这样开始:

int value = 123;
bgw1.RunWorkerAsync(argument: value);  // the int will be boxed

然后

private void worker_DoWork(object sender, DoWorkEventArgs e) 
{
   int value = (int) e.Argument;   // the 'argument' parameter resurfaces here

   ...

   // and to transport a result back to the main thread
   double result = 0.1 * value;
   e.Result = result;
}


// the Completed handler should follow this pattern 
// for Error and (optionally) Cancellation handling
private void worker_Completed(object sender, RunWorkerCompletedEventArgs e) 
{
  // check error, check cancel, then use result
  if (e.Error != null)
  {
     // handle the error
  }
  else if (e.Cancelled)
  {
     // handle cancellation
  }
  else
  {          
      double result = (double) e.Result;
      // use it on the UI thread
  }
  // general cleanup code, runs when there was an error or not.
}

Answer 2

虽然这是一个已经回答的问题,但我还有另外一个选择,即IMO更容易阅读:

BackgroundWorker worker = new BackgroundWorker();
worker.DoWork += (obj, e) => WorkerDoWork(value, text);
worker.RunWorkerAsync();

并在处理程序方法上:

private void WorkerDoWork(int value, string text) {
    ...
}

Answer 3

你可以像这样传递多个参数.

List<object> arguments = new List<object>();
                    arguments.Add(argument 1);
                    arguments.Add(argument 1);
                    arguments.Add(argument n);


                    backgroundWorker2.RunWorkerAsync(arguments);

private void worker_DoWork(object sender, DoWorkEventArgs e) {

  List<object> genericlist = e.Argument as List<object>;
  extract your multiple arguments from this list and cast them and use them. 

}

Answer 4

您可以使用该DoWorkEventArgs.Argument物业.

可以在Microsoft的站点上找到完整的示例(甚至使用int参数):

• 如何:在后台运行操作

Answer 5

查看DoWorkEventArgs.Argument属性:

...
backgroundWorker1.RunWorkerAsync(yourInt);
...

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    // Do not access the form's BackgroundWorker reference directly.
    // Instead, use the reference provided by the sender parameter.
    BackgroundWorker bw = sender as BackgroundWorker;

    // Extract the argument.
    int arg = (int)e.Argument;

    // Start the time-consuming operation.
    e.Result = TimeConsumingOperation(bw, arg);

    // If the operation was canceled by the user, 
    // set the DoWorkEventArgs.Cancel property to true.
    if (bw.CancellationPending)
    {
        e.Cancel = true;
    }
}

Answer 6

您需要RunWorkerAsync(object)方法和DoWorkEventArgs.Argument属性。

worker.RunWorkerAsync(5);

private void worker_DoWork(object sender, DoWorkEventArgs e) {
    int argument = (int)e.Argument; //5
}

Answer 7

如果你想传递多种类型的参数,你可以试试这个,首先将它们全部添加到Object类型的数组中,并将该对象传递给RunWorkerAsync()这里是一个例子:

   some_Method(){
   List<string> excludeList = new List<string>(); // list of strings
   string newPath ="some path";  // normal string
   Object[] args = {newPath,excludeList };
            backgroundAnalyzer.RunWorkerAsync(args);
      }

现在在后台工作者的doWork方法中

backgroundAnalyzer_DoWork(object sender, DoWorkEventArgs e)
      {
        backgroundAnalyzer.ReportProgress(50);
        Object[] arg = e.Argument as Object[];
        string path= (string)arg[0];
        List<string> lst = (List<string>) arg[1];
        .......
        // do something......
        //.....
       }