任务/多线程处理时的单例可绑定控件

Question

在发布这个问题之前，我做了 10 天的研究，所以真的希望有人能够为解决这个问题提供一些线索。

问题是，一旦单例类的绑定列表发生更改，任何可绑定控件都不会更新。这是多线程应用程序上的常见问题。大多数（如果不是全部）解决方案都提供建议，其中绑定列表或集合从父线程初始化，然后进行一些调用。不是我要找的。如果使用静态类而不是单例，同样的问题仍然存在。

基本上，应用程序会触发一些任务，这些任务又会在不同的业务类上创建对象。这些对象将消息发布到绑定列表中，这应该会更新 UI 列表框，但实际上却没有。是的，消息对象位于列表中，并且在任务完成后绑定（显示项目）。锁定/解锁对象访问也不是问题。

感谢任何建议/解决方案

业务对象的精简版本：

namespace MyNameSpace
{
    public class Message
    {
        private string messageSummary;
        public Message() { }
        public string MessageSummary
        {
            set { messageSummary = value; }
            get { return messageSummary; }
        }
    }
}

执行某些操作的另一个类的精简版本：

namespace MyNameSpace
{
    public class WorkDoingClass
    {
        public WorkDoingClass() { }
        public void DoSomeWork()
        {
            //some routines
            Message messageObj = new Message();
            messageObj.MessageSummary = "DoSOmrWork Finished";
        }

        public void DoSomeOtherWork()
        {
            //some routines
            Message messageObj = new Message();
            messageObj.MessageSummary = "DoSomeOtherWork Finished";
            AllMessages.Instance.AllMessagesBindingList.Add(messageObj);
        }
    }
}

单例：

namespace MyNameSpace
{
    public sealed class AllMessages
    {
        private static readonly AllMessages _instance = new AllMessages();
        private BindingList<Message> _allMessagesBL;

        public WorkDoingClass() { _allMessagesBL = new BindingList<Message>(); }

        public static AllMessages Instance
        {
            get { return _instance; }
        }

        public BindingList<Message> AllMessagesBindingList
        {
            get { return _allMessagesBL};
        }
    }
}

这也是调用开始处的精简版本：

namespace MyNameSpace
{
    public partial class Form1 : Form
    {
        private Task _TaskSqlData;
        private CancellationTokenSource cTokenSourceSql;

        public Form1()
        {
            InitializeComponent();
            listBox1.DataSource = AllMessages.Instance.AllMessagesBindingList;
            listBox1.DisplayMember = "MessageSummary";
        }

    private void button1_Click(object sender, EventArgs e)
    {
            cTokenSourceSql = new CancellationTokenSource();
            var tokenSqlData = cTokenSourceSql.Token;
            if (this._TaskSqlData != null)
            {
                if (this._TaskSqlData.Status == TaskStatus.Running)
                    this.cTokenSourceSql.Cancel();
                this._TaskSqlData.Dispose();
                this._TaskSqlData = null;
            }
            _TaskSqlData = Task.Factory.StartNew(()
                            => StartDoingWork(this, tokenSqlData, null), tokenSqlData);
    }

    public void StartDoingWork(object sender, CancellationToken ct, EventArgs e)
    {
            if (ct.IsCancellationRequested)
                ct.ThrowIfCancellationRequested();
            WorkDoingClass work = new WorkDoingClass();
            work.DoSomeOtherWork();
    }

Answer 1

您的问题是创建列表框的线程（主 UI 线程）与修改集合的线程（工作线程）不同。

尝试以下代码。它可以解决你的问题。我使用 SynchronizationContext 来同步两个线程，它与 Control.Invoke()。

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        private Task _TaskSqlData;
        private CancellationTokenSource cTokenSourceSql;
        WorkDoingClass _work;

        public Form1()
        {
            InitializeComponent();
            listBox1.DataSource = AllMessages.Instance.AllMessagesBindingList;
            listBox1.DisplayMember = "MessageSummary";
            _work = new WorkDoingClass(SynchronizationContext.Current);
        }

        private void button1_Click(object sender, EventArgs e)
        {
            cTokenSourceSql = new CancellationTokenSource();
            var tokenSqlData = cTokenSourceSql.Token;
            if (this._TaskSqlData != null)
            {
                if (this._TaskSqlData.Status == TaskStatus.Running)
                    this.cTokenSourceSql.Cancel();
                this._TaskSqlData.Dispose();
                this._TaskSqlData = null;
            }
            _TaskSqlData = Task.Factory.StartNew(()
                            => StartDoingWork(this, tokenSqlData, null), tokenSqlData);
        }

        public void StartDoingWork(object sender, CancellationToken ct, EventArgs e)
        {
            if (ct.IsCancellationRequested)
                ct.ThrowIfCancellationRequested();

            _work.DoSomeOtherWork();
        }
    }

    public class Message
    {
        private string messageSummary;
        public Message() { }
        public string MessageSummary
        {
            set { messageSummary = value; }
            get { return messageSummary; }
        }
    }

    public class WorkDoingClass
    {
        private SynchronizationContext _syncContext;

        public WorkDoingClass() { }

        public WorkDoingClass(SynchronizationContext _syncContext)
        {
            // TODO: Complete member initialization
            this._syncContext = _syncContext;
        }
        public void DoSomeWork()
        {
            //some routines
            Message messageObj = new Message();
            messageObj.MessageSummary = "DoSOmrWork Finished";
        }

        public void DoSomeOtherWork()
        {
            _syncContext.Send(DoWork, null);
        }

        private static void DoWork(object arg)
        {
            //some routines
            Message messageObj = new Message();
            messageObj.MessageSummary = "DoSomeOtherWork Finished";
            AllMessages.Instance.AllMessagesBindingList.Add(messageObj);
        }
    }

    public sealed class AllMessages
    {
        private static readonly AllMessages _instance = new AllMessages();
        private BindingList<Message> _allMessagesBL;

        public AllMessages() { _allMessagesBL = new BindingList<Message>(); }

        public static AllMessages Instance
        {
            get { return _instance; }
        }

        public BindingList<Message> AllMessagesBindingList
        {
            get { return _allMessagesBL; }
        }
    }
}