all. I have a problem with uploading of the file in Silverlight application. Here is a code sample. In case when this file is opened in other application (excel or word for example) it fails to open it, otherwise it's working fine. I'm using OpenFileDialog to choose the file and pass it to this function.
private byte[] GetFileContent(FileInfo file)
{
var result = new byte[] {};
try
{
using (var fs = file.OpenRead())
{
result = new byte[file.Length];
fs.Read(result, 0, (int)file.Length);
}
}
catch (Exception e)
{
// File is in use
}
return result;
}
Is there any way i can access this file or should i just notify the user that the file is locked?
You should notify the user that the file is currently in use by another program. If another program has the file open with a lock that does allow a shared read there is no way to bypass this lock.
Related
I want to write entries to a log file stored in Azure file storage. I currently have this:
var log = "My log entry";
var client = _storageAccount.CreateCloudFileClient();
var share = client.GetShareReference(Config.LogShare);
share.CreateIfNotExists();
var root = share.GetRootDirectoryReference();
var logfile = root.GetFileReference("log.txt");
if (!logfile.Exists()) logfile.Create(0);
// What goes here to append to the file...?
I can see plenty of examples of how to do this with Blobs, or how to upload an entire file, but how do I just append to an existing file?
I have tried this:
var buffer = Encoding.GetEncoding("UTF-8").GetBytes(log.ToCharArray());
using (var fileStream = logfile.OpenWrite(0)) {
fileStream.Write(buffer, (int)logfile.Properties.Length, buffer.Length);
}
But then I get this error:
The remote server returned an error: (416) The range specified is invalid for the current size of the resource..
I managed to work this out myself. You just need to increase the size of the file by the number of new bytes you want to write to it, and then write the new data to that new empty space at the end of the file, like this:
var client = _storageAccount.CreateCloudFileClient();
var share = client.GetShareReference(Config.LogShare);
share.CreateIfNotExists();
var root = share.GetRootDirectoryReference();
var logfile = root.GetFileReference("log.txt");
if (!logfile.Exists()) logfile.Create(0);
var buffer = Encoding.UTF8.GetBytes($"{log}\r\n");
logfile.Resize(logfile.Properties.Length + buffer.Length);
using (var fileStream = logfile.OpenWrite(null)) {
fileStream.Seek(buffer.Length * -1, SeekOrigin.End);
fileStream.Write(buffer, 0, buffer.Length);
}
You can do this with blobs https://blogs.msdn.microsoft.com/windowsazurestorage/2015/04/13/introducing-azure-storage-append-blob/
Shame it doesn't work with files too
Azure file storage REST API doesn't support appending to an existing file. To achieve this, please mount the file share to your machine as a drive, and append to the file just like simple local files.
Actually, I don't think you really need appending functionality per your code above. You can specify the file size in CloudFile.OpenWrite() / CloudFile.Create(), or try CloudFile.UploadFromStream() instead of CloudFile.OpenWrite().
This error could also be due to multi-threaded access.
I bet if you tried to lock the file before you access it, you will not face this problem.
There are many ways to update the file.
Since you already managed to get the share, the root, the folder and the file.. Here is a portion of my code that worked for me.
if (!fileLock.IsWriteLockHeld) fileLock.EnterWriteLock();
try
{
using (var stream = new MemoryStream(content, false))
{
file.UploadFromStream(stream, null, options);
}
}
catch (Exception ex)
{
File.AppendAllText(FileName, ex.ToString());
}
finally
{
if (fileLock.IsWriteLockHeld)
fileLock.ExitWriteLock();
}
Where fileLock is declared as:
protected ReaderWriterLockSlim fileLock = new ReaderWriterLockSlim();
Having said that, I am not saying that this is the best way ever to do it.
The two things I would like you to keep in mind :
1-Lock the resource that is likely to be accessed by more than one thread (That is so common in AZURE)
2- Get familiar with asynchronous methods that Azure provides.. use them when they suit well.
Coming back to your original problem about appending to the existing file..
All the methods of the CloudFile will overwrite the existing file. Cloud Files are not for frequent writing, and they indeed impact performance if you keep writing on them frequently, add the lock impact on performance, they will be horrible.
Cloud files are meant to store big bulk of data once and for all, if you want to add another bulk you have the choice of creating another file.
Have all your data with the client till they reach some size and create an algorith to select the file name and upload them all at once.
I am using jdeveloper version 11.1.1.5.0. In my use case I have created Mail Client Send Mail program where I used ADF InputFile component to attach File on mail.
But problem is that InputFile Component only return path of file(only get file name). And in my mail program DataSource class use full path to access file name.
UploadedFile uploadfile=(UploadedFile) actionEvent.getNewValue();
String fname= uploadfile.getFilename();//this line only get file name.
So how can I get full path using adf InputFile component or any other way to fulfill my requirement.
You could save the uploaded file in a path at the server. Only take care about naming that file, because of concurrency of users you should follow a policy about it, for example, adding te time in milliseconds to the name of the file. Like this...
private String writeToFile(UploadedFile file) {
ServletContext servletCtx =
(ServletContext)FacesContext.getCurrentInstance().getExternalContext().getContext();
String fileDirPath = servletCtx.getRealPath("/files/tmp");
String fileName = getTimeInMilis()+file.getFilename();
try {
InputStream is = file.getInputStream();
OutputStream os =
new FileOutputStream(fileDirPath + "/"+fileName);
int readData;
while ((readData = is.read()) != -1) {
os.write(readData);
}
is.close();
os.close();
} catch (IOException ex) {
ex.printStackTrace();
}
return fileName;
}
This method also returns the new name of the uploaded file. You can replace getTimeInMilis() with any naming policy you like.
It would be a security issue if a web app is able to see anything other than the data stream for an uploaded file. The directory structure of the client would not be exposed to the webapp. As such, unless you plan to upload the file from the same host as the server, you will not have access to the file path on the client.
Note: Using answer instead of comment due to reputation threshold
So I have a program where I am able to successfully create a .csv file with my data.
I now have to somehow print that file.
I looked up a lot of resources about printing in WPF but they are all so complex and I can't make head and tails of what the barebones printing statements are.
Is there a way for me to just tell the application to take a specific filepath and then print the contents of the file as it would be if I manually went and opened the .csv file and hit print?
Edit:
Alternatively, I have been told I could do this; take a screenshot of my screen (printscreen) and then tell the printer to print the image from clipboard. But this has to be all done when a button called 'Print' is pressed.
Update:
For my first query, what I'm doing now is opening the .csv file when I press the print button and then using excel's print function to get my printout and its working.
But I would like to have it work with what is seen directly in the application with the printscreen method.
You can use the "Verb" property of ProcessStartInfo with Process.Start to open and print the CSV file with the default program associated with CSV files. You need to set the "Verb" to "print".
using System;
using System.Diagnostics;
using System.ComponentModel;
namespace MyProcessSample
{
class MyProcess
{
public static void Main()
{
Process myProcess = new Process();
try
{
myProcess.StartInfo.UseShellExecute = true;
myProcess.StartInfo.FileName = "C:\\myfile.csv";
myProcess.StartInfo.CreateNoWindow = true;
myProcess.StartInfo.Verb = "print";
myProcess.Start();
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
}
}
}
Hi I have a wpf application that plays sounds on events such as button click. And the current code I have now plays the sound file, but Ive realized that it has to be in another folder which for example if the user deletes, makes the application pretty much not useable.
I was wondering, How could I get a .wav file without creating a whole new folder in the application Release directory.
Any ideas?
Thanks.
If the .wav files is added to your project at the root then marked as content (Right Click on the .wav file and click properties. Then change the build action to content) then it will be copied directly to the root output folder
You can the reference the wav file in code or XAML as a relative path (simple "Myfile.wav")
I believe this is what you are asking for?
How about putting the .wav-file as en embedded resource in the dll?
Just add the file to the project, right-click on the file and set Build Action to Embedded Resource.
Then you can load the .wav file as a stream and save it to disc like this:
private void WriteEmbeddedResourceToFile(string writePath, string assemblyName)
{
Assembly asm = Assembly.GetExecutingAssembly();
Stream s = asm.GetManifestResourceStream(assemblyName);
if (s != null)
{
var file = new byte[s.Length];
s.Read(file, 0, (int)s.Length);
File.WriteAllBytes(writePath, file);
s.Close();
}
}
The string assemblyName must be set like this: namespace.(if you put the file in a folder, insert folder subpath here).filename.wav
Alternatively, you can drop saving it to disc, and just use the stream directly:
private byte[] GetEmbeddedResource(string assemblyName)
{
Assembly asm = Assembly.GetExecutingAssembly();
Stream s = asm.GetManifestResourceStream(assemblyName);
if (s != null)
{
var file = new byte[s.Length];
s.Read(file, 0, (int)s.Length);
s.Close();
return file;
}
}
Then, when you want to load the file, GetEmbeddedResource will return the byte array.
I am trying to do a file upload from Silverlight(Client Object Model) to Sharepoint 2010 library.. Please see the code below..
try{
context = new ClientContext("http://deepu-pc/");
web = context.Web;
context.Load(web);
OpenFileDialog oFileDialog = new OpenFileDialog();
oFileDialog.FilterIndex = 1;
oFileDialog.Multiselect = false;
if (oFileDialog.ShowDialog().Value == true)
{
var localFile = new FileCreationInformation();
localFile.Content = System.IO.File.ReadAllBytes(oFileDialog.File.FullName);
localFile.Url = System.IO.Path.GetFileName(oFileDialog.File.Name);
List docs = web.Lists.GetByTitle("Gallery");
context.Load(docs);
File file = docs.RootFolder.Files.Add(localFile);
context.Load(file);
context.ExecuteQueryAsync(OnSiteLoadSuccess, OnSiteLoadFailure);
}
}
catch (Exception exp)
{
MessageBox.Show(exp.ToString());
}
But I am getting the following error
System.Security.SecurityException: File operation not permitted. Access to path '' is denied.
at System.IO.FileSecurityState.EnsureState()
at System.IO.FileSystemInfo.get_FullName()
at ImageUploadSilverlight.MainPage.FileUpload_Click(Object sender, RoutedEventArgs e)
Any help would be appreciated
Thanks
Deepu
Silverlight runs with very restricted access to the client user's filesystem. When using an open-file dialog, you can get the name of the selected file within its parent folder, the length of the file, and a stream from which to read the data in the file, but not much more than that. You can't read the full path of the file selected, and you are getting the exception because you are attempting to do precisely that.
If you want to read the entire content of the file into a byte array, you'll have to replace the line
localFile.Content = System.IO.File.ReadAllBytes(oFileDialog.File.FullName);
with something like
localFile.content = ReadFully(oFileDialog.File.OpenRead());
The ReadFully method reads the entire content of a stream into a byte array. It's not a standard Silverlight method; instead it
is taken from this answer. (I gave this method a quick test on Silverlight, and it appears to work.)