Question

我有一些文件要从ftp服务器下载。我想要实现的是：

在SplitContainer的其中一个面板中有一个ListView MainForm。
我想要下载文件列表，为ProgressBar

Label

ListView

在ProgressChanged事件中，我想显示ProgressBar上文件的当前进度以及Label

这是我的代码的最新版本：

internal async Task GetFiles(IEnumerable<string> urlList)
{
    string dir = Environment.CurrentDirectory + "\\updates";
    Directory.CreateDirectory(dir);
    var tasks = new List<Task>();

    foreach (var url in urlList)
        tasks.Add(DownloadFile(url, dir));

    await Task.WhenAll(tasks);
}

internal async Task DownloadFile(string url, string dir)
{
    string filename = Helper.GetFilenameFromUrl(url);
    ProgressBar pb = CreateFileDownloadBar();
    Label lb = CreateFileDownloadLabel();
    Stopwatch sw = new Stopwatch();
    Helper.CrossThreadInvoke(_sender, () => _sender.listView1.Controls.Add(pb));
    Helper.CrossThreadInvoke(_sender, () => _sender.listView1.Controls.Add(lb));

    using (var client = new WebClient())
    {
        client.DownloadProgressChanged += new DownloadProgressChangedEventHandler((sender, e) => ProgressChanged(sender, e, sw, pb, lb));
        client.DownloadFileCompleted += new AsyncCompletedEventHandler((sender, e) => Completed(sender, e, sw));
        Helper.CrossThreadInvoke(_sender, () => _sender.lblFileDownload.Text = Helper.GetFilenameFromUrl(url));
        await client.DownloadFileTaskAsync(url, string.Concat(dir, "\\", filename));
    }
}

private Label CreateFileDownloadLabel()
{
    Label lb = new Label()
    {
        Location = new System.Drawing.Point(_sender.offset - 180, 5 + offset)
    };
    return lb;
}

private ProgressBar CreateFileDownloadBar()
{
    ProgressBar pb = new ProgressBar()
    {
        Location = new System.Drawing.Point(5, 5 + offset),
        Size = new System.Drawing.Size(200, 20)
    };

    offset += pb.Height + 5;

    return pb;
}

private void ProgressChanged(object sender, DownloadProgressChangedEventArgs e, Stopwatch sw, ProgressBar pb, Label lb)
{
    pb.Value = e.ProgressPercentage;
    lb.Text = string.Format("{0} kb/s", (e.BytesReceived / 1024d / sw.Elapsed.TotalSeconds).ToString("0.00"));        
}

但是，该事件中的pb和lb不会更新MainForm上的控件。我怀疑它是因为我操作它的本地副本，而不是我添加到MainForm的副本，但我不知道如何使其工作。我是否需要某种类型的计数器CrossThreadInvoke类似

ProgressBar pb = Helper.CrossThreadInvoke(_sender, () => _sender.listView1.Controls[counter] as ProgressBar;
pb.Value = e.ProgressPercentage;

然而，这似乎是不必要的复杂，所以我想知道是否有更好的方法。

Answer 1

我已经为你做了一个很小的例子，它真的不漂亮，但应该让你知道如何实现进步。

此外，我已经评论了很多内容并插入了一些演示代码。

关键是使用Controls.Invoke（） - 方法，如果你在不同的线程/任务。

示例

public partial class Form1 : Form { public Form1() { InitializeComponent(); var l = new List<string>(); for (int i = 0; i < 10; i++) { l.Add("Some Text" + i); } Task.Factory.StartNew(async () => { await GetFiles(l, this); }); } private int ctrlCount = 0; public void AddControlToListView(Control c) { if (c is Label) { c.Location = new Point(205, ctrlCount * c.Height + 5); } else { c.Location = new Point(5, ctrlCount * c.Height + 5); } if (this.listView1.InvokeRequired) { this.listView1.Invoke(new Action<Control>(this.listView1.Controls.Add), c); this.listView1.Invoke(new Action(this.listView1.Update)); } else { this.listView1.Controls.Add(c); this.listView1.Update(); } ctrlCount++; } internal async Task GetFiles(IEnumerable<string> urlList, Form1 parent) { //string dir = Environment.CurrentDirectory + "\\updates"; //Directory.CreateDirectory(dir); var tasks = new List<Task>(); foreach (var url in urlList) tasks.Add(DownloadFile(url, "")); await Task.WhenAll(tasks); } internal async Task DownloadFile(string url, string dir) { string filename = "";// Helper.GetFilenameFromUrl(url); ProgressBar pb = CreateFileDownloadBar(); Label lb = CreateFileDownloadLabel(); this.AddControlToListView(pb); this.AddControlToListView(lb); Stopwatch sw = new Stopwatch(); //Helper.CrossThreadInvoke(_sender, () => _sender.listView1.Controls.Add(pb)); //Helper.CrossThreadInvoke(_sender, () => _sender.listView1.Controls.Add(lb)); await Task.Factory.StartNew(() => { for (int i = 1; i < 11; i++) { pb.Invoke(new MethodInvoker(delegate { pb.Value = i * 10; })); lb.Invoke(new MethodInvoker(delegate { lb.Text = (i * 10).ToString(); })); Thread.Sleep(500); } }); using (var client = new WebClient()) { client.DownloadProgressChanged += new DownloadProgressChangedEventHandler((sender, e) => ProgressChanged(sender, e, sw, pb, lb)); //client.DownloadFileCompleted += new AsyncCompletedEventHandler((sender, e) => Completed(sender, e, sw)); //Helper.CrossThreadInvoke(_sender, () => _sender.lblFileDownload.Text = Helper.GetFilenameFromUrl(url)); //await client.DownloadFileTaskAsync(url, string.Concat(dir, "\\", filename)); } } private Label CreateFileDownloadLabel() { Label lb = new Label() { Text = "Hello" //Location = new System.Drawing.Point(_sender.offset - 180, 5 + offset) }; return lb; } private ProgressBar CreateFileDownloadBar() { ProgressBar pb = new ProgressBar() { //Location = new System.Drawing.Point(5, 5 + offset), Size = new System.Drawing.Size(200, 20) }; //offset += pb.Height + 5; return pb; } private void ProgressChanged(object sender, DownloadProgressChangedEventArgs e, Stopwatch sw, ProgressBar pb, Label lb) { pb.Value = e.ProgressPercentage; lb.Text = string.Format("{0} kb/s", (e.BytesReceived / 1024d / sw.Elapsed.TotalSeconds).ToString("0.00")); } }

我希望这可以让您了解如何创建和更新ProgressBars

以父表格控制的事件

1 个答案: