I tried to download file like this:
WebClient _downloadClient = new WebClient();
_downloadClient.DownloadFileCompleted += DownloadFileCompleted;
_downloadClient.DownloadFileAsync(current.url, _filename);
// ...
And after downloading I need to start another process with download file, I tried to use DownloadFileCompleted event.
void DownloadFileCompleted(object sender, System.ComponentModel.AsyncCompletedEventArgs e)
{
if (e.Error != null)
{
throw e.Error;
}
if (!_downloadFileVersion.Any())
{
complited = true;
}
DownloadFile();
}
But, i cannot know name of downloaded file from AsyncCompletedEventArgs , I made my own
public class DownloadCompliteEventArgs: EventArgs
{
private string _fileName;
public string fileName
{
get
{
return _fileName;
}
set
{
_fileName = value;
}
}
public DownloadCompliteEventArgs(string name)
{
fileName = name;
}
}
But I cannot understand how call my event instead DownloadFileCompleted
Sorry if it's nood question
One way is to create a closure.
WebClient _downloadClient = new WebClient();
_downloadClient.DownloadFileCompleted += DownloadFileCompleted(_filename);
_downloadClient.DownloadFileAsync(current.url, _filename);
This means your DownloadFileCompleted needs to return the event handler.
public AsyncCompletedEventHandler DownloadFileCompleted(string filename)
{
Action<object, AsyncCompletedEventArgs> action = (sender, e) =>
{
var _filename = filename;
if (e.Error != null)
{
throw e.Error;
}
if (!_downloadFileVersion.Any())
{
complited = true;
}
DownloadFile();
};
return new AsyncCompletedEventHandler(action);
}
The reason I create the variable called _filename is so that the filename variable passed into the DownloadFileComplete method is captured and stored in the closure. If you didn't do this you wouldn't have access to the filename variable within the closure.
I was playing around DownloadFileCompleted to get the file path/file name From the event. I've tried the above solution also but It was not like my expectation then i fond the solution by adding Querystring value, Here i would like to share the code with you.
string fileIdentifier="value to remember";
WebClient webClient = new WebClient();
webClient.DownloadFileCompleted += new AsyncCompletedEventHandler (DownloadFileCompleted);
webClient.QueryString.Add("file", fileIdentifier); // here you can add values
webClient.DownloadFileAsync(new Uri((string)dyndwnldfile.path), localFilePath);
And the event can be defined as like this:
private void DownloadFileCompleted(object sender, AsyncCompletedEventArgs e)
{
string fileIdentifier= ((System.Net.WebClient)(sender)).QueryString["file"];
// process with fileIdentifier
}
Related
I am trying to trigger and event after the WokbookDeactivate event is finished because I need to write some metadata into the file and it can be done only when the Excel file is completely closed.
While using WokbookDeactivate the workbook still appears as active and if I try to run the code that access the excel file it raises an exception "is being used by another process..."
ThisAddin_Startup
private void ThisAddIn_Startup(object sender, System.EventArgs e)
{
this.Application.WorkbookOpen += new Excel.AppEvents_WorkbookOpenEventHandler(Application_WorkbookOpen);
this.Application.WorkbookDeactivate += Application_WorkbookDeactivate;
}
EventHandler
void Application_WorkbookDeactivate(Microsoft.Office.Interop.Excel.Workbook Wb)
{
Excel.Application excelApp = this.Application;
string filePath = excelApp.ActiveWorkbook.FullName;
string userName = GeneralFunctions.getUser();
try
{
if (File.Exists(filePath) && Metadata.ContainsKey(filePath) && Metadata[filePath])
{
Metadata.Remove(filePath);
}
}
catch (Exception)
{
throw;
}
finally
{
}
}
After Deactivate I need to run another event that check if the key of the excel file was removed from the Metadata. That means I can edit the document using the OpenXML function...
I tried to attach two events to the Deactivate, but the excel workbook is still open when the first one finishes.
Any idea?
Another approach:
I created a Timer property System.Timers.Timer _tm; and call a method to initialize it.
void Application_WorkbookDeactivate(Excel.Workbook Wb)
{
Excel.Application excelApp = this.Application;
string filePath = excelApp.ActiveWorkbook.FullName;
try
{
if (File.Exists(filePath) && Metadata.ContainsKey(filePath) && Metadata[filePath] && Wb.FullName.Equals(filePath))
{
StartWrite(filePath);
}
}
catch (Exception)
{
throw;
}
}
private void StartWrite(string filePath)
{
_tm = new System.Timers.Timer(2000);
_tm.Elapsed += (sender, args) => _tm_Elapsed(sender, filePath);
_tm.Enabled = true;
}
void _tm_Elapsed(object sender, string filePath)
{
try
{
((System.Timers.Timer)sender).Enabled = false;
string userName = GeneralFunctions.getUser();
if (this.Application != null && Metadata[filePath])
{
// Do stuff with the file
_tm.Stop();
}
}
catch (Exception)
{
throw;
}
}
1: Can someone explain the last line of the first function to me?
2: The second function doesn't work. Please tell me why.The PHP script is fetching the data.
I edited the code to get this, but the app now crashes with a System nullreferenceexception.
Please help.
private void checkbutton_Click(object sender, RoutedEventArgs e)
{
statustext.Text = "Checking for new score";
var webclient = new WebClient();
webclient.OpenReadCompleted += new OpenReadCompletedEventHandler(getscores_OpenReadCompleted);
webclient.OpenReadAsync(new Uri("http://example.com/get.php?"+DateTime.Now));
}
void getscores_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
{
StreamReader s = null;
Stream reply=null;
try
{
reply = (Stream)e.Result;
s = new StreamReader(reply);
}
catch
{
statustext.Text = "ERROR IN FETCHING";
}
scorebox.Text = s.ReadToEnd();
statustext.Text = "DoNE";
}
The last line of the first method is attaching a handler to an event. It is saying that when the OpenReadCompleted event fires, that is to say when the read completes, the getscores_OpenReadCompleted method should be called.
The getscores_OpenReadCompleted doesn't work because it's trying to access a UI element from a non-UI thread.
You're also adding the handler after starting the asynchronous operation, so while it's unlikely, it's certainly possible that the operation completes very quickly and the event is fired before you add the handler. While this situation would be very unusual, it's fixed very quickly and easily by simply adding the handler before you start the asynchronous operation.
There are a couple of issues here:
Register the delegate before the call to OpenReadAsync
Read the stream from the event arguments and close the stream when you're done.
private void checkbutton_Click(object sender, RoutedEventArgs e)
{
statustext.Text = "Checking for new score";
var webclient = new WebClient();
webclient.OpenReadCompleted += new OpenReadCompletedEventHandler(getscores_OpenReadCompleted);
webclient.OpenReadAsync(new Uri("http://example.com/get.php?"+DateTime.Now));
}
void getscores_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
{
Stream reply = null;
StreamReader s = null;
string outputText = string.Empty;
try
{
reply = (Stream)e.Result;
s = new StreamReader(reply);
outputText = s.ReadToEnd();
}
finally
{
if (s != null)
{
s.Close();
}
if (reply != null)
{
reply.Close();
}
}
statustext.Text = outputText;
}
See the usage of the OpenReadAsync method here:
http://msdn.microsoft.com/en-us/library/system.net.openreadcompletedeventhandler(v=vs.110).aspx
and here
http://msdn.microsoft.com/en-us/library/ms144211(v=vs.110).aspx
This is mt first time trying to write a not web based program, and my first time writing anything in C#.
I need a program that monitors folders, but I can't get it to work.
I have used the example from this post Using FileSystemWatcher with multiple files but is trying to make it a form.
My current problem comes in the ProcessQueue function where fileList apparently is defined in another thread.
Whenever a file is actually submitted to the watched folder I get an error that using fileList is a cross thread call
Can anyone explain this error to me, and how to fix it?
namespace matasWatch
{
public partial class Form1 : Form
{
private int n = 1;
private bool isWatching = false;
private List<string> filePaths;
private System.Timers.Timer processTimer;
private string watchedPath;
private FileSystemWatcher watcher;
public Form1()
{
filePaths = new List<string>();
watchedPath = "C:\\Users\\username\\Desktop\\test";
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
if (!isWatching)
{
button1.Text = "Stop";
isWatching = true;
watcher = new FileSystemWatcher();
watcher.Filter = "*.*";
watcher.Created += Watcher_FileCreated;
watcher.Error += Watcher_Error;
watcher.Path = watchedPath;
watcher.IncludeSubdirectories = true;
watcher.EnableRaisingEvents = true;
}
else {
button1.Text = "Watch";
isWatching = false;
watcher.EnableRaisingEvents = false;
watcher.Dispose();
watcher = null;
}
}
private void Watcher_Error(object sender, ErrorEventArgs e)
{
// Watcher crashed. Re-init.
isWatching = false;
button1_Click(sender, e);
}
private void Watcher_FileCreated(object sender, FileSystemEventArgs e)
{
filePaths.Add(e.FullPath);
if (processTimer == null)
{
// First file, start timer.
processTimer = new System.Timers.Timer(2000);
processTimer.Elapsed += ProcessQueue;
processTimer.Start();
}
else{
// Subsequent file, reset timer.
processTimer.Stop();
processTimer.Start();
}
}
private void ProcessQueue(object sender, ElapsedEventArgs args)
{
try
{
fileList.BeginUpdate();
foreach (string filePath in filePaths)
{
fileList.Items.Add("Blaa");
}
fileList.EndUpdate();
filePaths.Clear();
}
finally
{
if (processTimer != null)
{
processTimer.Stop();
processTimer.Dispose();
processTimer = null;
}
}
}
}
}
I assume that fileList is a windows forms control. The ProcessQueue method is called from a timer thread which is by default a background thread. The fileList control resides in the UI thread. You need to use the Invoke() method of the form passing it in a delegate the updates the fileList control.
Invoke(new Action(() =>
{
fileList.BeginUpdate();
foreach (string filePath in filePaths)
{
fileList.Items.Add("Blaa");
}
fileList.EndUpdate();
filePaths.Clear();
}));
Try using System.Windows.Forms.Timer instead of System.Timers.Timer so the timer tick event is executed on the UI thread.
See here for more details.
How can I get the URL in OpenReadCompletedEvent when I use webclient.
WebClient webClient = new WebClient();
webClient.OpenReadAsync(url); // in event method I want get this url
webClient.OpenReadCompleted += new OpenReadCompletedEventHandler(CardInfoDown_Completed);
private void CardInfoDown_Completed(object sender, OpenReadCompletedEventArgs e)
{
if (e.Error == null)
{
using (System.IO.StreamReader reader = new System.IO.StreamReader(e.Result))
{
// I want get the url here,
// How to do this?
string strStream = reader.ReadToEnd();
}
}
}
Thank you!
WebClient webClient = new WebClient();
webClient.BaseAddress = "http://hhh.com";
webClient.OpenReadAsync(new Uri("http://hhh.com")); // in event method I want get this url
webClient.OpenReadCompleted += new OpenReadCompletedEventHandler(CardInfoDown_Completed);
And:
private void CardInfoDown_Completed(object sender, OpenReadCompletedEventArgs e)
{
if (e.Error == null)
{
using (System.IO.StreamReader reader = new System.IO.StreamReader(e.Result))
{
// I want get the url here,
// How to do this?
var client = sender as WebClient;
if (client != null)
{
var url = client.BaseAddress; //returns hhh.com
}
string strStream = reader.ReadToEnd();
}
}
Anton Sizikov's solution is good, but will only work if the URL is absolute (like http://hhh.com). If using a relative URL, .NET will automatically merge the base address with the relative URL (therefore potentially resulting in an invalid URL).
To send a value to the OpenReadCompleted event handler, you're supposed to use this OpenRead overload to provide a custom token (in this case, your URL): http://msdn.microsoft.com/en-us/library/ms144212(v=vs.95).aspx
WebClient webClient = new WebClient();
webClient.OpenReadAsync(new Uri("http://hhh.com"), "http://hhh.com");
webClient.OpenReadCompleted += new OpenReadCompletedEventHandler(CardInfoDown_Completed);
Then to retrieve the value:
private void CardInfoDown_Completed(object sender, OpenReadCompletedEventArgs e)
{
if (e.Error == null)
{
using (System.IO.StreamReader reader = new System.IO.StreamReader(e.Result))
{
var url = (string)e.UserState;
string strStream = reader.ReadToEnd();
}
}
}
For me even a simpler variation from the above works fine
private void CardInfoDown_Completed(object sender, DownloadStringCompletedEventArgs e)
{
string url;
if (e.Error == null)
{
url = (string)e.UserState;
}
// ...
}
It has been surprisingly hard to find a code example of downloading multiple files using the webclient class asynchronous method, but downloading one at a time.
How can I initiate a async download, but wait until the first is finished until the second, etc. Basically a que.
(note I do not want to use the sync method, because of the increased functionality of the async method.)
The below code starts all my downloads at once. (the progress bar is all over the place)
private void downloadFile(string url)
{
WebClient client = new WebClient();
client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(client_DownloadProgressChanged);
client.DownloadFileCompleted += new AsyncCompletedEventHandler(client_DownloadFileCompleted);
// Starts the download
btnGetDownload.Text = "Downloading...";
btnGetDownload.Enabled = false;
progressBar1.Visible = true;
lblFileName.Text = url;
lblFileName.Visible = true;
string FileName = url.Substring(url.LastIndexOf("/") + 1,
(url.Length - url.LastIndexOf("/") - 1));
client.DownloadFileAsync(new Uri(url), "C:\\Test4\\" + FileName);
}
void client_DownloadFileCompleted(object sender, AsyncCompletedEventArgs e)
{
}
void client_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
{
double bytesIn = double.Parse(e.BytesReceived.ToString());
double totalBytes = double.Parse(e.TotalBytesToReceive.ToString());
double percentage = bytesIn / totalBytes * 100;
progressBar1.Value = int.Parse(Math.Truncate(percentage).ToString());
}
What I have done is populate a Queue containing all my urls, then I download each item in the queue. When there are no items left, I can then process all the items. I've mocked some code up below. Keep in mind, the code below is for downloading strings and not files. It shouldn't be too difficult to modify the below code.
private Queue<string> _items = new Queue<string>();
private List<string> _results = new List<string>();
private void PopulateItemsQueue()
{
_items.Enqueue("some_url_here");
_items.Enqueue("perhaps_another_here");
_items.Enqueue("and_a_third_item_as_well");
DownloadItem();
}
private void DownloadItem()
{
if (_items.Any())
{
var nextItem = _items.Dequeue();
var webClient = new WebClient();
webClient.DownloadStringCompleted += OnGetDownloadedStringCompleted;
webClient.DownloadStringAsync(new Uri(nextItem));
return;
}
ProcessResults(_results);
}
private void OnGetDownloadedStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
if (e.Error == null && !string.IsNullOrEmpty(e.Result))
{
// do something with e.Result string.
_results.Add(e.Result);
}
DownloadItem();
}
Edit:
I've modified your code to use a Queue. Not entirely sure how you wanted progress to work. I'm sure if you wanted the progress to cater for all downloads, then you could store the item count in the 'PopulateItemsQueue()' method and use that field in the progress changed method.
private Queue<string> _downloadUrls = new Queue<string>();
private void downloadFile(IEnumerable<string> urls)
{
foreach (var url in urls)
{
_downloadUrls.Enqueue(url);
}
// Starts the download
btnGetDownload.Text = "Downloading...";
btnGetDownload.Enabled = false;
progressBar1.Visible = true;
lblFileName.Visible = true;
DownloadFile();
}
private void DownloadFile()
{
if (_downloadUrls.Any())
{
WebClient client = new WebClient();
client.DownloadProgressChanged += client_DownloadProgressChanged;
client.DownloadFileCompleted += client_DownloadFileCompleted;
var url = _downloadUrls.Dequeue();
string FileName = url.Substring(url.LastIndexOf("/") + 1,
(url.Length - url.LastIndexOf("/") - 1));
client.DownloadFileAsync(new Uri(url), "C:\\Test4\\" + FileName);
lblFileName.Text = url;
return;
}
// End of the download
btnGetDownload.Text = "Download Complete";
}
private void client_DownloadFileCompleted(object sender, AsyncCompletedEventArgs e)
{
if (e.Error != null)
{
// handle error scenario
throw e.Error;
}
if (e.Cancelled)
{
// handle cancelled scenario
}
DownloadFile();
}
void client_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
{
double bytesIn = double.Parse(e.BytesReceived.ToString());
double totalBytes = double.Parse(e.TotalBytesToReceive.ToString());
double percentage = bytesIn / totalBytes * 100;
progressBar1.Value = int.Parse(Math.Truncate(percentage).ToString());
}
I am struggling to understand where the issue is. If you only call the async method for the first file, won't it only download that file? Why not use the client_downlaodFileCompleted event to initiate the next file download based on some value passed by AsyncCompletedEvents, or maintain a list of downloaded files as a static variable and have client_DownloadFileCompleted iterate tht list to find the next file to download.
Hope that helps but please post more information if I have miunderstood your question.
I would make a new method, for example named getUrlFromQueue which returns me a new url from the queue (collection or array) and deletes it.. then it calls downloadFile(url) - and in client_DownloadFileCompleted I call getUrlFromQueue again.