【发布时间】：2016-12-28 23:51:42
【问题描述】：
在 form1 中，我在另一个类中创建 List imagesUrls 后启动了 backgroundworker。
但是我在 dowork 事件和 progresschanged 事件中得到的是在 progressBar1 和 label2 上，我看到它按 10 计数：10,20,30,40....100% 然后是达到 100% 会引发异常。
例外：
附加信息：调用目标已引发异常。
例外是在Program.cs就行了：
Application.Run(new Form1());
我想要的是从列表 imagesUrls 下载每个文件，并将每个文件下载进度的 progressBar 和 label2 从 0% 更新到 100%，由 1 而不是 10：1、2、3、4、5.. .100 每个文件下载报告从 0 到 100 的下载进度
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.IO;
using System.Net;
using System.Threading;
namespace SatelliteImages
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
ExtractImages ei = new ExtractImages();
ei.Init();
backgroundWorker1.RunWorkerAsync();
}
private void Form1_Load(object sender, EventArgs e)
{
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
for (int i = 1; i <= ExtractImages.imagesUrls.Count(); i++)
{
if (worker.CancellationPending == true)
{
e.Cancel = true;
break;
}
else
{
using (var client = new WebClient())
{
client.DownloadFile(ExtractImages.imagesUrls[i], @"C:\Temp\TestingSatelliteImagesDownload\" + i + ".jpg");
System.Threading.Thread.Sleep(500);
worker.ReportProgress(i * 10);
}
}
}
}
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
progressBar1.Value = e.ProgressPercentage;
label2.Text = (e.ProgressPercentage.ToString() + "%");
}
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
}
}
}
然后我有我创建列表 imagesUrls 的类： 当我运行程序时，有时我会遇到异常而不是所有时间。
远程服务器返回错误：(500) Internal Server Error.
System.Net.WebException was unhandled
HResult=-2146233079
Message=The remote server returned an error: (500) Internal Server Error.
Source=System
StackTrace:
at System.Net.WebClient.DownloadDataInternal(Uri address, WebRequest& request)
at System.Net.WebClient.DownloadData(Uri address)
at System.Net.WebClient.DownloadData(String address)
at SatelliteImages.ExtractImages.ExtractDateAndTime(String baseAddress) in D:\C-Sharp\SatelliteImages\SatelliteImages\SatelliteImages\ExtractImages.cs:line 97
at SatelliteImages.ExtractImages.Init() in D:\C-Sharp\SatelliteImages\SatelliteImages\SatelliteImages\ExtractImages.cs:line 30
at SatelliteImages.Form1..ctor() in D:\C-Sharp\SatelliteImages\SatelliteImages\SatelliteImages\Form1.cs:line 26
at SatelliteImages.Program.Main() in D:\C-Sharp\SatelliteImages\SatelliteImages\SatelliteImages\Program.cs:line 19
at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
InnerException:
以及类代码：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Net;
using System.Xml;
using HtmlAgilityPack;
namespace SatelliteImages
{
class ExtractImages
{
static WebClient client;
static string htmltoextract;
public static List<string> countriescodes = new List<string>();
public static List<string> countriesnames = new List<string>();
public static List<string> DatesAndTimes = new List<string>();
public static List<string> imagesUrls = new List<string>();
static string firstUrlPart = "http://www.sat24.com/image2.ashx?region=";
static string secondUrlPart = "&time=";
static string thirdUrlPart = "&ir=";
public void Init()
{
ExtractCountires();
foreach (string cc in countriescodes)
{
ExtractDateAndTime("http://www.sat24.com/image2.ashx?region=" + cc);
}
ImagesLinks();
}
public static void ExtractCountires()
{
try
{
htmltoextract = "http://sat24.com/en/?ir=true";//"http://sat24.com/en/";// + regions;
client = new WebClient();
client.DownloadFile(htmltoextract, @"c:\temp\sat24.html");
client.Dispose();
string tag1 = "<li><a href=\"/en/";
string tag2 = "</a></li>";
string s = System.IO.File.ReadAllText(@"c:\temp\sat24.html");
s = s.Substring(s.IndexOf(tag1));
s = s.Substring(0, s.LastIndexOf(tag2) + tag2.ToCharArray().Length);
s = s.Replace("\r", "").Replace("\n", "").Replace(" ", "");
string[] parts = s.Split(new string[] { tag1, tag2 }, StringSplitOptions.RemoveEmptyEntries);
string tag3 = "<li><ahref=\"/en/";
for (int i = 0; i < parts.Length; i++)
{
if (i == 17)
{
//break;
}
string l = "";
if (parts[i].Contains(tag3))
l = parts[i].Replace(tag3, "");
string z1 = l.Substring(0, l.IndexOf('"'));
if (z1.Contains("</ul></li><liclass="))
{
z1 = z1.Replace("</ul></li><liclass=", "af");
}
countriescodes.Add(z1);
countriescodes.GroupBy(n => n).Any(c => c.Count() > 1);
string z2 = parts[i].Substring(parts[i].LastIndexOf('>') + 1);
if (z2.Contains("&"))
{
z2 = z2.Replace("&", " & ");
}
countriesnames.Add(z2);
countriesnames.GroupBy(n => n).Any(c => c.Count() > 1);
}
}
catch (Exception e)
{
}
}
public static void ExtractDateAndTime(string baseAddress)
{
var wc = new WebClient();
wc.BaseAddress = baseAddress;
HtmlDocument doc = new HtmlDocument();
var temp = wc.DownloadData("/en");
doc.Load(new MemoryStream(temp));
var secTokenScript = doc.DocumentNode.Descendants()
.Where(e =>
String.Compare(e.Name, "script", true) == 0 &&
String.Compare(e.ParentNode.Name, "div", true) == 0 &&
e.InnerText.Length > 0 &&
e.InnerText.Trim().StartsWith("var region")
).FirstOrDefault().InnerText;
var securityToken = secTokenScript;
securityToken = securityToken.Substring(0, securityToken.IndexOf("arrayImageTimes.push"));
securityToken = secTokenScript.Substring(securityToken.Length).Replace("arrayImageTimes.push('", "").Replace("')", "");
var dates = securityToken.Trim().Split(new string[] { ";" }, StringSplitOptions.RemoveEmptyEntries);
var scriptDates = dates.Select(x => new ScriptDate { DateString = x });
foreach (var date in scriptDates)
{
DatesAndTimes.Add(date.DateString);
}
}
public class ScriptDate
{
public string DateString { get; set; }
public int Year
{
get
{
return Convert.ToInt32(this.DateString.Substring(0, 4));
}
}
public int Month
{
get
{
return Convert.ToInt32(this.DateString.Substring(4, 2));
}
}
public int Day
{
get
{
return Convert.ToInt32(this.DateString.Substring(6, 2));
}
}
public int Hours
{
get
{
return Convert.ToInt32(this.DateString.Substring(8, 2));
}
}
public int Minutes
{
get
{
return Convert.ToInt32(this.DateString.Substring(10, 2));
}
}
}
public void ImagesLinks()
{
int cnt = 0;
foreach (string countryCode in countriescodes)
{
cnt++;
for (; cnt < DatesAndTimes.Count(); cnt++)
{
string imageUrl = firstUrlPart + countryCode + secondUrlPart + DatesAndTimes[cnt] + thirdUrlPart + "true";
imagesUrls.Add(imageUrl);
if (cnt % 10 == 0) break;
}
}
}
}
}
关于班级：
我应该如何处理异常？一般来说，我想通过再次尝试操作来处理，因为我会在每次 X 次时更新列表 imagesUrls，如果出现异常，请再次尝试操作而不是停止。
如何在 form1 中使用带有 backgroundworker 的类？因此，当它第一次在课堂上下载所有文件时，它也会在 form1 progressBar1 和 label2 上显示下载进度。
但首先要解决 form1 代码中的问题，然后还要处理类。
【问题讨论】：
-
查看我关于进度条的回答here。我还提供了一个详细的示例来帮助您。
-
您是否有来自服务器的日志（或某种获取更多详细信息的方式）？错误 500 很笼统。
标签： c# .net multithreading winforms