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在form1中，我在另一個類中創建List imagesUrls之後開始了backgroundworker。爲什麼使用backgroundworker工作不好，有時候我收到異常？
但是我得到的dowork事件，然後在progresschanged事件是在progressBar1上，也在label2上，我看到它是由10計數：10,20,30,40 .... 100％然後當它達到100％，它拋出異常。
例外：
附加信息：異常已被調用的目標拋出。
唯一的例外是在上線的Program.cs：
Application.Run(new Form1());
我想是從列表中imagesUrls下載各個文件和更新進度，並從0每個文件下載進度LABEL2 ％至1 100％不是10的：1,2,3,4,5 ... 100每個文件下載到報告從0下載的進度，100
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)
{
}
}
}
然後我有類我創建列表imagesUrls： 當我運行程序有時我得到異常沒有所有的時間。
遠程服務器返回錯誤：（500）內部服務器錯誤。
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:
和類代碼：
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;
}
}
}
}
}
關於類：
我應該如何處理異常？我通常想要通過再次嘗試操作來處理，因爲我會每次X更新列表imagesUrls我想要的時候，如果有異常，請再次嘗試操作並且不要停止。
如何在form1中使用backgroundworker類？因此，當它首次在該類中下載所有文件時，它將在form1 progressBar1和label2上顯示下載進度。
但首先要解決form1代碼中的問題，然後處理該類。
看到我的答案[here]（http://stackoverflow.com/questions/41370300/how-can-i-use-two-progressbar-controls-to-display-each-file-download-progress-an/ 41370508＃41370508）關於進度條。我還提供了一個詳細的例子來幫助你。 – CodingYoshi
您是否有來自服務器的日誌（或獲取更多詳細信息的方式）？錯誤500是非常通用的。 – EJoshuaS