在加载xml文件的过程中如何使用进度栏

问题描述

我想在加载远程xml文件时显示进度栏.我在Visual C#2008 Express Edition中使用Windows应用程序窗体.

I want to show progress bar during loading a Remote xml file. I am using Windows Application Form in Visual C# 2008 Express Edition.

private void button1_Click(object sender, EventArgs e)
    {
        string text =  textBox1.Text;
        string url = "http://api.bing.net/xml.aspx?AppId=XXX&Query=" + text + "&Sources=Translation&Version=2.2&Market=en-us&Translation.SourceLanguage=en&Translation.TargetLanguage=De";

        XmlDocument xml = new XmlDocument();
        xml.Load(url);

        XmlNodeList node = xml.GetElementsByTagName("tra:TranslatedTerm");

        for (int x = 0; x < node.Count; x++ )
        {
            textBox2.Text = node[x].InnerText;
            progressbar1.Value = x;
        }
    }

以上代码不适用于显示进度条加载..请向我建议一些代码.预先感谢

Above code is not working for showing progressbar loading.. Please Suggest me some code. Thanks in advance

推荐答案

您想在进度条上反映什么?是下载文件(因为文件很大)还是处理文件?

What exacly do you want to reflect by progress bar? Rather downloading the file (because it's big) or processing the file?

您的进度条不会更改，因为您的方法是同步的-结束时不会发生任何其他事情. BackgroundWorker 类专门针对此类问题而设计.它以异步方式完成主要工作，并且能够报告进度已更改.这是更改游览方法以使用它的方法:

Your progress bar doesn't change because your method is synchronous - nothing else will happen unit it ends. BackgroundWorker class is designed perfectly for this kind of problems. It does main work in an asynchronous manner and is able to report that progress has changed. Here is how to change tour method to use it:

private void button1_Click(object sender, EventArgs e)
{
    string text =  textBox1.Text;
    string url = "http://api.bing.net/xml.aspx?AppId=XXX&Query=" + text + "&Sources=Translation&Version=2.2&Market=en-us&Translation.SourceLanguage=en&Translation.TargetLanguage=De";

    XmlDocument xml = new XmlDocument();
    xml.Load(url);
    XmlNodeList node = xml.GetElementsByTagName("tra:TranslatedTerm");

    BackgroundWorker worker = new BackgroundWorker();

    // tell the background worker it can report progress
    worker.WorkerReportsProgress = true;

    // add our event handlers
    worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(this.RunWorkerCompleted);
    worker.ProgressChanged += new ProgressChangedEventHandler(this.ProgressChanged);
    worker.DoWork += new DoWorkEventHandler(this.DoWork);

    // start the worker thread
    worker.RunWorkerAsync(node);
}

现在，主要部分:

private void DoWork(object sender, DoWorkEventArgs e)
{
   // get a reference to the worker that started this request
   BackgroundWorker workerSender = sender as BackgroundWorker;

   // get a node list from agrument passed to RunWorkerAsync
   XmlNodeList node = e.Argument as XmlNodeList;

   for (int i = 0; x < node.Count; i++)
   {
       textBox2.Text = node[i].InnerText;
       workerSender.ReportProgress(node.Count / i);
   }
}

private void RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    // do something after work is completed     
}

public void ProgressChanged( object sender, ProgressChangedEventArgs e )
{
    progressBar.Value = e.ProgressPercentage;
}

进度条反映下载文件

尝试使用 HttpWebRequest 将文件作为流获取.

// Create a 'WebRequest' object with the specified url. 
WebRequest myWebRequest = WebRequest.Create(url); 

// Send the 'WebRequest' and wait for response.
WebResponse myWebResponse = myWebRequest.GetResponse(); 

// Obtain a 'Stream' object associated with the response object.
Stream myStream = myWebResponse.GetResponseStream();

long myStreamLenght = myWebResponse.ContentLength;

因此，现在您知道此XML文件的长度.然后，您必须异步地从流中读取内容( BackgroundWorker 和是个好主意).使用 myStream.Position 和 myStreamLenght 计算进度.

So now you know the length of this XML file. Then you have to asynchronously read the content from stream (BackgroundWorker and StreamReader is a good idea). Use myStream.Position and myStreamLenght to calculate the progress.

我知道我不是很专一，但我只是想为您指明正确的方向.我认为在这里写所有这些事情没有意义.在这里，您将具有可帮助您处理 Stream 和 BackgroundWorker 的链接:

I know that I'm not very specific but I just wanted to put you in the right direction. I think it doesn't make sense to write about all those things here. Here you have links that will help you dealing with Stream and BackgroundWorker:

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