如何在不阻止UI的情况下等待线程完成 [英] How to wait for thread to complete without blocking UI

问题描述

我希望我的程序在下面的行之后等待

I want my program to wait after below line

frmProgressBarObj = PullMSI.ExtractByMSIName("products.txt", false);

上面的

方法是通过StartProcessWithProgress()方法在内部调用线程.我希望在//代码逻辑-2行执行之前完成该线程.同时，它不应停止由frmProgressBar.UpdateProgress()完成的UI更新.我该怎么做呢?

as above method is internally calling thread through StartProcessWithProgress() method . I want that thread to be completed before //code logic -2 line gets executed. At the same time, It should not stop UI update done by frmProgressBar.UpdateProgress(). How do I do this?

namespace NS1
{
    public partial class frmMain : Form
    {                
        private void button1_Click(object sender, EventArgs e)
        {
            frmProgressBar frmProgressBarObj = PullMSI.ExtractByMSIName("products.txt", false);
            //code logic - 2
            MessageBox.Show("This is executing immediately. 
                             I want to wait until above thread is complete");
        }
    }

    public partial class frmProgressBar : Form
    {

        public void UpdateProgress(String strTextToDisplayOnProgress)
        {
            progressBar1.BeginInvoke(
                   new Action(() => 
                   { 
                       progressBar1.Value++; 
                       lblFileName.Text = strTextToDisplayOnProgress;
                       if (progressBar1.Value == progressBar1.Maximum)
                       {
                           this.Hide(); 
                        } 
                    }));
        }

        public delegate void DelProgress();

        public void StartProcessWithProgress(DelProgress delMethodCode, int maxCount)
        {
            InitializeProgress(maxCount);
            Thread backgroundThread = new Thread(new ThreadStart(delMethodCode));
            backgroundThread.Start();
        }
    }

    public static class PullMSI
    {
        public static frmProgressBar ExtractByMSIName(String strProductFilePath, bool reNameMSI)
        {
            frmProgressBar frmProgressBar = new frmProgressBar();

            frmProgressBar.StartProcessWithProgress(() =>
            {
                //StreamRader sr declaration and other code

                while (!sr.EndOfStream)
                {
                    //logic here
                    frmProgressBar.UpdateProgress("Copying sr.msiname");
                }
            }, 2);

            return frmProgressBar;
        }
    }
}

推荐答案

我很惊讶您以前没有使用过这些方法，但是我真的建议您阅读有关C#中线程的知识，因为理解复杂性从根本上来说很重要并学习语言.

I'm very surprised you haven't worked with any of these before but I would really recommend reading about threading in C# since it's fundamentally important to understand the intricacies and learning the language.

以下是您实现所需目标的三种不同方式:

Below are three different ways you can achieve what you want:

1.使用重置事件(进一步阅读:

1. Using reset events (further reading: https://msdn.microsoft.com/en-us/library/system.threading.manualreseteventslim(v=vs.110).aspx). If your C# version doesn't have the ManualResetEventSlim, replace it with ManualResetEvent and change Wait() with WaitOne()

class LockingWithResetEvents
{
    private readonly ManualResetEvent _resetEvent = new ManualResetEvent(false);

    public void Test()
    {
        MethodUsingResetEvents();
    }

    private void MethodUsingResetEvents()
    {
        ThreadPool.QueueUserWorkItem(_ => DoSomethingLong());
        ThreadPool.QueueUserWorkItem(_ => ShowMessageBox());
    }

    private void DoSomethingLong()
    {
        Console.WriteLine("Doing somthing.");
        Thread.Sleep(1000);
        _resetEvent.Set();
    }

    private void ShowMessageBox()
    {
        _resetEvent.WaitOne();
        Console.WriteLine("Hello world.");
    }
}

2)使用任务并行库(TPL).进一步阅读:

3)使用异步/等待.进一步阅读: https://msdn.microsoft.com/zh-我们/library/hh191443.aspx

class LockingWithAwait
{
    public void Test()
    {
        DoSomething();
    }

    private async void DoSomething()
    {
        await Task.Run(() => DoSomethingLong());
        ShowMessageBox();
    }

    private async void DoSomethingLong()
    {
        Console.WriteLine("Doing somthing.");
        Thread.Sleep(10000);
    }

    private void ShowMessageBox()
    {
        Console.WriteLine("Hello world.");
    }
}

也要知道:Mutex( https://msdn.microsoft.com/en-us/library/system. threading.semaphore(v = vs.110).aspx )，锁定( https://msdn.microsoft.com/en-us/library/c5kehkcz.aspx )，SemaphoreSlim( https://msdn.microsoft.com/zh-CN/library/system.threading.monitor(v=vs.110).aspx)和互锁的( https: //msdn.microsoft.com/zh-CN/library/system.threading.interlocked(v=vs.110).aspx ).

Also good to know: Mutex (https://msdn.microsoft.com/en-us/library/system.threading.mutex(v=vs.110).aspx), Semaphore (https://msdn.microsoft.com/en-us/library/system.threading.semaphore(v=vs.110).aspx), Lock (https://msdn.microsoft.com/en-us/library/c5kehkcz.aspx), SemaphoreSlim (https://msdn.microsoft.com/en-us/library/system.threading.semaphoreslim(v=vs.110).aspx), Monitor (https://msdn.microsoft.com/en-us/library/system.threading.monitor(v=vs.110).aspx) and Interlocked (https://msdn.microsoft.com/en-us/library/system.threading.interlocked(v=vs.110).aspx).

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