控制'progressBar1'从我在业务类中创建的线程以外的线程访问[duplicate]

Posted 2021-03-30

这个问题在这里已有答案：

• Reporting progress from Async Task 1回答

我在另一个dll中有一个方法可以获取大量数据（占用22k行），我需要为用户创建一个进度条。

如果我不异步调用此方法，它会挂起应用程序。但是，当我异步调用它时，我得到错误progressBar1控件从一个线程访问，而不是它创建的线程

private void btnSend_Click(object sender, EventArgs e)
{
    string filePath = tbPath.Text;

    ETLBusiness etlBusiness = new ETLBusiness(filePath);

    Task.Run(() => etlBusiness.LoadData(progressBar1));

}

在这种情况下，backgroundWorker1.RunWorkerAsync不是异步的，它在循环中停止我的应用程序

private void btnSend_Click(object sender, EventArgs e)
{
    string filePath = tbPath.Text;

    ETLBusiness etlBusiness = new ETLBusiness(filePath);

    Func<ProgressBar,int> func = etlBusiness.LoadData;

    this.backgroundWorker1.RunWorkerAsync(func(progressBar1));

}

怎么修好了？

答案

你的问题是你的控件存在于线程A上，但你试图通过线程B访问它。这是一个'禁忌'。请尝试以下代码

private void btnSend_Click(object sender, EventArgs e)
{
    Task.Run(() => LoadData(System.Threading.SynchronizationContext.Current, progressBar1));
}

private void LoadData (System.Threading.SynchronizationContext synchContext, ProgressBar1ObjectType progressBar)
{
    string filePath = tbPath.Text;
    ETLBusiness etlBusiness = new ETLBusiness(filePath);

    synchContext.Post(state => etlBusiness.LoadData(progressBar), null);
}

其中'ProgressBar1ObjectType'是progressBar1的类型

这是另一种可能更好的选择：

Thread _myThread = null;
private void btnSend_Click(object sender, EventArgs e)
{
    SynchronizationContext synchContext = SynchronizationContext.Current;
    _myThread = new Thread(() => LoadData(synchContext, progressBar1));

    myThread.Start();

}

private void LoadData (System.Threading.SynchronizationContext synchContext, ProgressBar1ObjectType progressBar)
{
    string filePath = tbPath.Text;
    ETLBusiness etlBusiness = new ETLBusiness(filePath);

    synchContext.Post(state => etlBusiness.LoadData(progressBar), null);
    _myThread.Abort();
}