在BackgroundWorker线程中下载文件时GUI冻结

发布于 2024-11-08 07:04:02 字数 874 浏览 3 评论 0原文

在 BackgroundWorker 线程（以 RunWorkerAsync() 启动）中，我想通过 HttpWebRequest 从服务器下载文件。一旦我调用 GetResponse()，从服务器下载文件时 GUI 就会保持冻结状态。这实际上不应该发生，因为 BackgroundWorker 或多或少与带有一些装饰（如进度处理和取消）的线程相同。谁能解释一下为什么会发生这种情况？

这里是代码片段：

            if ((lRequest = (HttpWebRequest)WebRequest.Create(lURL)) != null)
            {
                if ((lResponse = lRequest.GetResponse()) != null)
                {
                    lRemoteStream = lResponse.GetResponseStream();
                    lLocalStream = File.Create(lTempFileName);

                    do
                    {
                        lBytesRead = lRemoteStream.Read(lTemp, 0, lTemp.Length);
                        lLocalStream.Write(lTemp, 0, lBytesRead);
                    } while (lBytesRead > 0);
                }
            }

原文

In the BackgroundWorker thread (started with RunWorkerAsync()) I want to download files from a server via HttpWebRequest. As soon as I call GetResponse() the GUI is remains freezed while the file is downloaded from the server. This actually shouldn't happen as a BackgroundWorker is more or less the same as a thread with some decoration like progress handling and cancellation. Can anybody explain me why this is happening?

Here the code snippet :

            if ((lRequest = (HttpWebRequest)WebRequest.Create(lURL)) != null)
            {
                if ((lResponse = lRequest.GetResponse()) != null)
                {
                    lRemoteStream = lResponse.GetResponseStream();
                    lLocalStream = File.Create(lTempFileName);

                    do
                    {
                        lBytesRead = lRemoteStream.Read(lTemp, 0, lTemp.Length);
                        lLocalStream.Write(lTemp, 0, lBytesRead);
                    } while (lBytesRead > 0);
                }
            }

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影子的影子 2024-11-15 07:04:13

与此同时，我发现了问题，如果我听了你的话，你可能已经回答了我的问题：/

如果你启动BackgroundWorker线程，请小心你不要指向UI主线程。
就我而言，我是这样做的：

    private void BW_FriendInRequest_DoWork(object sender, DoWorkEventArgs e)
    {
        while (true)
        {
            if (this.isLoggedIn)
                listIncomingRequests();

            Thread.Sleep(Config.mMessagesCheckSleep);
        }
    }


    private delegate void listIncomingRequestsDelegate();
    private void listIncomingRequests()
    {
        if (InvokeRequired)
        {
            listIncomingRequestsDelegate d = new listIncomingRequestsDelegate(listIncomingRequests);
            this.Invoke(d, new object[] { });
            return;
        }
       ...
    }

一旦我删除“InvokeRequired”，冻结效果就消失了。

in the meantime i've found the problem and if i had listened to you you had probably answered my question already :/

if you start BackgroundWorker threads be careful you don't point back to the UI main thread.
in my case i did it this way :

    private void BW_FriendInRequest_DoWork(object sender, DoWorkEventArgs e)
    {
        while (true)
        {
            if (this.isLoggedIn)
                listIncomingRequests();

            Thread.Sleep(Config.mMessagesCheckSleep);
        }
    }


    private delegate void listIncomingRequestsDelegate();
    private void listIncomingRequests()
    {
        if (InvokeRequired)
        {
            listIncomingRequestsDelegate d = new listIncomingRequestsDelegate(listIncomingRequests);
            this.Invoke(d, new object[] { });
            return;
        }
       ...
    }

as soon as i removed the "InvokeRequired" the freezing effect had gone.

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