blocks|key|1541732|text|根据您的模型，您可以让工作线程在完成其工作时回调其创建者(或其他进程)，或者必须频繁地轮询工作线程以查看是否已完成，如果已完成，则获取结果。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1541733|等待工作线程返回其结果的想法破坏了多线程的好处。|1541734|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Depending on your model, you either want to have your worker thread call back to its creator (or to some other process) when it's finished its work, or you have to poll the worker thread every so often to see if it's done and, if so, get the result.

The idea of waiting for a worker thread to return its result undermines the benefits of multithreading.

blocks|key|1541788|text|RunWorkerAsync()异步启动进程，并在进程实际完成之前返回并继续执行您的代码。如果您希望获得BackgroundWorker的结果，则需要创建一个实例变量来保存该值，并在BackgroundWorker完成后对其进行检查。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1541789|如果您想等到工作完成，那么您不需要BackgroundWorker。|1541790|entityMap^0|0|G|1G|G|2J|G|0|H|G|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|I|$]]

<code>RunWorkerAsync()</code> starts the process asynchronously and will return and continue executing your code before the process actually completes. If you want to obtain the result of the <code>BackgroundWorker</code>, you'll need to create an instance variable to hold that value and check it once the <code>BackgroundWorker</code> completes.

If you want to wait until the work is finished, then you don't need a <code>BackgroundWorker</code>.

blocks|key|1326678|text|你可以让你的线程以对象作为参数引发一个事件：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1326679|ThreadFinishedEvent(this,+new+ThreadEventArgs(object));|code-block|syntax|javascript|1326680|其中：|1326681|public+class+ThreadEventArgs+:+EventArgs
{
++++public+ThreadEventArgs(object+object)
++++{
++++++++Object+=+object
++++}

++++public+object+Object
++++{
++++++++get;+private+set;
++++}
}|1326682|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

You could have your thread raise an event with the object as an argument:

<pre><code>ThreadFinishedEvent(this, new ThreadEventArgs(object));
</code></pre>

where:

<pre><code>public class ThreadEventArgs : EventArgs
{
 public ThreadEventArgs(object object)
 {
 Object = object
 }

 public object Object
 {
 get; private set;
 }
}
</code></pre>

blocks|key|1541878|text|在BackgroundWorker+(后台工作发生的地方)的DoWork事件处理程序中，有一个参数DoWorkEventArgs。此对象具有公共属性对象结果。当您的worker生成其结果(在您的示例中是一个List<FileInfo>)时，将e.Result设置为该值，然后返回。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1541879|现在您的BackgroundWorker已经完成了它的任务，它触发了RunWorkerCompleted事件，该事件有一个RunWorkerCompletedEventArgs对象作为参数。RunWorkerCompletedEventArgs.Result将包含来自BackgroundWorker的结果。|1541880|示例：|1541881|private+void+bgw_DoWork(object+sender,+DoWorkEventArgs+e)
{
++++int+result+=+2%2B2;
++++e.Result+=+result;
}

private+void+bgw_RunWorkerCompleted(object+sender,+RunWorkerCompletedEventArgs+e)
{
++++int+result+=+(int)e.Result;
++++MessageBox.Show("Result+received:+"+%2B+result.ToString());
}|code-block|syntax|javascript|1541882|entityMap^0|1|G|U|6|1D|F|2V|E|3D|8|0|Y|I|1P|R|2N|Y|3Q|G|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]|$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|11|8|@$9|12|A|13|B|C]|$9|14|A|15|B|C]|$9|16|A|17|B|C]|$9|18|A|19|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|1A|8|@]|D|@]|E|$]]|$1|J|3|K|5|L|7|1B|8|@]|D|@]|E|$M|N]]|$1|O|3|-4|5|6|7|1C|8|@]|D|@]|E|$]]]|P|$]]

In your <code>DoWork</code> event handler for the <code>BackgroundWorker</code> (which is where the background work takes place) there is an argument <code>DoWorkEventArgs</code>. This object has a public property object Result. When your worker has generated its result (in your case, a <code>List&lt;FileInfo&gt;</code>), set <code>e.Result</code> to that, and return.

Now that your BackgroundWorker has completed its task, it triggers the <code>RunWorkerCompleted</code> event, which has a <code>RunWorkerCompletedEventArgs</code> object as an argument. <code>RunWorkerCompletedEventArgs.Result</code> will contain the result from your <code>BackgroundWorker</code>.

example:

<pre><code>private void bgw_DoWork(object sender, DoWorkEventArgs e)
{
 int result = 2+2;
 e.Result = result;
}

private void bgw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
 int result = (int)e.Result;
 MessageBox.Show("Result received: " + result.ToString());
}
</code></pre>

blocks|key|1541945|text|一般来说，当运行异步进程时，工作线程应该调用委托或触发事件(如ChrisF)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1541946|您可以查看新的PFX，它具有一些可以返回值的并发函数。|1541947|例如，有一个名为Parallel.ForEach()的函数，它有一个可以返回值的重载。|1541948|请查看此以了解更多信息|1541949|http://msdn.microsoft.com/en-us/magazine/cc817396.aspx|offset|length|1541950|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|0|0|1I|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|U|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|V|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|W|8|@]|9|@$J|X|K|Y|1|Z]]|A|$]]|$1|L|3|-4|5|6|7|10|8|@]|9|@]|A|$]]]|M|$N|$5|O|P|Q|A|$R|I]]]]

Generally speaking when running a process async, The worker thread should call a delegate or fire an event (like ChrisF).

You can check out the new PFX which has some concurrency function that can return values.

For example there is a function called Parallel.ForEach() which has an overload that can return a value.

check this out for more info

<a href="http://msdn.microsoft.com/en-us/magazine/cc817396.aspx" rel="nofollow noreferrer"><a href="http://msdn.microsoft.com/en-us/magazine/cc817396.aspx" rel="nofollow noreferrer">http://msdn.microsoft.com/en-us/magazine/cc817396.aspx</a></a>

blocks|key|1542010|text|不要在"DoWork“方法中做后台工作，而是创建一个返回您想要返回的类型的方法，并将其应用于e.Result，就像这里推荐的其他答案一样。作为一个最小的例子，在不使问题过于复杂的情况下回答OP的问题……|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1542011|++++++++private+List<FileInfo>+FileInfoWorker(object+sender,+DoWorkEventArgs+e)
++++{
++++++++return+new+List<FileInfo>(new+DirectoryInfo("C:\\SOTest").GetFiles().ToList());
++++}

++++private+void+bgwTest_DoWork(object+sender,+DoWorkEventArgs+e)
++++{
++++++++BackgroundWorker+worker+=+sender+as+BackgroundWorker;

++++++++e.Result+=+FileInfoWorker(worker,+e);
++++}

++++private+void+bgwTest_RunWorkerCompleted(object+sender,+RunWorkerCompletedEventArgs+e)
++++{
++++++++if+(e.Error+!=+null)
++++++++{
++++++++++++MessageBox.Show(e.Error.Message);
++++++++}
++++++++else+if+(e.Cancelled)
++++++++{
++++++++++++tbStatus.Text+=+"Background+operation+cancelled.";
++++++++}
++++++++else
++++++++{
++++++++++++tbStatus.Text+=+"Background+operation+complete.";
++++++++}
++++}|code-block|syntax|javascript|1542012|该示例还展示了如何从BackgroundWorker接口更新TextBox。未显示的是对通过ProgressBar和TextBoxes报告进度的支持，以及对取消的支持，这两者也在API中得到支持。代码是通过一个按钮运行的.|1542013|++++++++private+void+btnSOTest_Click(object+sender,+EventArgs+e)
++++{
++++++++bgwTest.RunWorkerAsync();
++++}|1542014|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Instead of doing the background work in the &quot;DoWork&quot; method, create a method that returns the type you want to return and apply that to e.Result as other answers here recommend. As a minimal example that answers the OP's question without overcomplicating the matter...
<pre><code> private List&lt;FileInfo&gt; FileInfoWorker(object sender, DoWorkEventArgs e)
 {
 return new List&lt;FileInfo&gt;(new DirectoryInfo(&quot;C:\\SOTest&quot;).GetFiles().ToList());
 }

 private void bgwTest_DoWork(object sender, DoWorkEventArgs e)
 {
 BackgroundWorker worker = sender as BackgroundWorker;

 e.Result = FileInfoWorker(worker, e);
 }

 private void bgwTest_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
 {
 if (e.Error != null)
 {
 MessageBox.Show(e.Error.Message);
 }
 else if (e.Cancelled)
 {
 tbStatus.Text = &quot;Background operation cancelled.&quot;;
 }
 else
 {
 tbStatus.Text = &quot;Background operation complete.&quot;;
 }
 }
</code></pre>
The example also shows how to update a TextBox from the BackgroundWorker API. Not shown is support for reporting progress via a ProgressBar and TextBoxes and support for cancellation, both are also supported in the API. The code is ran via a button...
<pre><code> private void btnSOTest_Click(object sender, EventArgs e)
 {
 bgwTest.RunWorkerAsync();
 }
</code></pre>

I need to make <code>RunWorkerAsync()</code> return a <code>List&lt;FileInfo&gt;</code>.
What is the process to be able to return an object from a background worker?

How to make BackgroundWorker return an object

我需要让RunWorkerAsync()返回一个List<FileInfo>。能够从后台工作进程返回对象的过程是什么？

问如何让BackgroundWorker返回一个对象
EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问如何让BackgroundWorker返回一个对象EN

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问如何让BackgroundWorker返回一个对象
EN