SynchronizationContext.Post到UI方法

Question

我正在使用Web服务,因此我需要扩展会话长度/重新连接并获取大型数据集等.有时这可能很长,所以我想在一个单独的线程中异步更新UI.

我似乎无法理解使用synchronizationContext在我的UI线程上调用方法.我有它,我已经将我的UIThread上下文传递给我的线程,现在我想更新UI线程上的一些标签等.我已经阅读了很多帖子,但似乎没有解释如何简单地将一些参数传递回方法,或者他们可能会这样做但是我太累了/傻到看到它.

//在主UI线程上

public void updateConnStatus(string conn_name, bool connected)
{
        switch (conn_name)
        {
            case "Conn" : if (connected == true){ //do something} break;

//在单独的线程上

uiContext.Post( //something to do with delegates in here that eludes me );

如果有人可以简单地解释我如何将sendOrPostCallBack链接到原始方法,我将非常感激.

谢谢

编辑:

我设法让代码运行并尝试触发事件,它填充我的自定义eventArgs好,但要么说它没有实例化updateUIConnStatus,需要更多的调查:o

public void updateUIThread(string conn, bool connected)
    {
       uiContext.Post(new SendOrPostCallback((o) => { updateConnStatus(this, new MyEventArgs<String, Boolean>(conn, connected)); }), null);
    }

public class MyEventArgs<T, U> : EventArgs
    {
        private T _val1; private U _val2;
        public  MyEventArgs(T value1, U value2) { _val1 = value1; _val2 = value2; }
        public T val1 { get { return _val1;} }
        public U val2 { get {return _val2;} }
    }

public event EventHandler<MyEventArgs<String, Boolean>> updateConnStatus = Delegate {};

//在UI Thread Now上

 public void updateConnStatus(object sender, MyEventArgs<String,Boolean> e)
    {
        switch (e.val1)
        {
            case "Conn1" :
                if (e.val2 == true)
                {

Answer 1

您需要SendOrPostCallback类型的委托.这很尴尬,它只需要一个类型为object的参数.你肯定应该看看.NET 4中提供的Task <>类来使这更容易.或者使用lambda,如下所示:

        string conn_name = "foo";
        uiContext.Post(new SendOrPostCallback((o) => {
            updateConnStatus(conn_name, true);
        }), null);

{braces}之间的代码在UI线程上执行.

Answer 2

通常,您在UI线程上创建类型的实例(例如ViewModels),因此您只需将SynchronizationContext或TaskScheduler(优选的恕我直言)保存到私有字段,然后在需要时进行比较...

private readonly SynchronizationContext _syncContext = SynchronizationContext.Current;
private readonly TaskScheduler _scheduler = TaskScheduler.Current;

void OnSomeEvent(object sender, EventArgs e)
{
    if (_syncContext != SynchronizationContext.Current)
    {
        // Use Send if you need to get something done as soon as possible.
        // We'll be polite by using Post to wait our turn in the queue.
        _syncContext.Post(o => DoSomething(), null);
        return;
    }
    // Call directly if we are already on the UI thread
    DoSomething();
}

void OnSomeOtherEvent(object sender, MyEventArgs e)
{
    var arg1 = e.Arg1; // "Hello "
    var arg2 = e.Arg2; // {"World", "!"};

    // Process args in the background, and then show the result to the user...
    // NOTE: We don't even need to check the context because we are passing
    // the appropriate scheduler to the continuation that shows a MessageBox.

    Task<string>.Factory.StartNew(() => ReturnSomething(arg1, arg2))
        .ContinueWith(t => MessageBox.Show(t.Result), _scheduler);
}

void DoSomething() { MessageBox.Show("Hello World!"); }

string ReturnSomething(string s, IEnumerable<string> list)
{
    return s + list.Aggregate((c, n) => c + n);
}