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DownloadFileAsync Method

Summary
Downloads an item asynchronously from a SharePoint server to a disk.

Syntax
C#
C++/CLI
Python
public void DownloadFileAsync( 
   Uri sourceUri, 
   string destinationFileName, 
   object userState 
) 
public: 
void DownloadFileAsync(  
   Uri^ sourceUri, 
   String^ destinationFileName, 
   Object^ userState 
)  
def DownloadFileAsync(self,sourceUri,destinationFileName,userState): 

Parameters

sourceUri
The full URI for the source item in the SharePoint server. This value cannot be null (Nothing in VB). It must be the URI to a valid SharePoint item, for example http://server/Shared Documents/File.ext

destinationFileName
The destination file name to download the item to. If the file already exists, it will be overwritten. This value cannot be null (Nothing in VB).

userState
The optional user-supplied state object that is used to identify the task that raised the DownloadCompleted event.

Remarks

This method will return control immediately to your program and the DownloadCompleted event will occur when the download operation is completed (whether or not the operation is successful).

To download a file synchronously, use the DownloadFile method.

To download an item to a stream, use the GetDownloadStream or GetDownloadStreamAsync method.

To upload an item to SharePoint, use the UploadFile, UploadFileAsync, UploadStream or UploadStreamAsync method.

Example

This example will download a document asynchronously at the specified SharePoint URI into a disk file and then get the image information using Leadtools.Codecs.RasterCodecs.

C#
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.SharePoint.Client; 
 
 
public void SharePointClientDownloadFileAsyncExample() 
{ 
   // Replace SHAREPOINT_SITE_URI with a valid URL to a SharePoint site, for example 
   // http://SiteCollection/MySite 
   Uri siteUri = new Uri(SHAREPOINT_SITE_URI); 
 
   // Replace SHAREPOINT_FOLDER_NAME with a valid folder on the site above, for example 
   // "Documents" or "Documents\Sub Documents" 
   string folderName = SHAREPOINT_FOLDER_NAME; 
 
   // Replace SHAREPOINT_DOCUMENT_NAME with a valid document on the folder above, for example 
   // MyDocument.tif 
   string documentName = SHAREPOINT_DOCUMENT_NAME; 
 
   // Build the full URL to the document are we going to download 
   UriBuilder builder = new UriBuilder(siteUri); 
   builder.Path = Path.Combine(builder.Path, folderName); 
   builder.Path = Path.Combine(builder.Path, documentName); 
   Uri sourceDocumentUri = builder.Uri; 
 
   SharePointClient spClient = new SharePointClient(); 
 
   // Optional: Set the credentials: 
   spClient.Credentials = new NetworkCredential(USER_NAME, PASSWORD, DOMAIN); 
 
   string tempFileName = Path.GetTempFileName(); 
 
   // If this is a console application demo, we might exit the program before the operation completes, 
   // so use a wait handle to not exit this method till the opreation completes 
   AutoResetEvent wait = new AutoResetEvent(false); 
 
   // Download the SharePoint item to the temporary file asynchronously 
   spClient.DownloadCompleted += new EventHandler<SharePointClientDownloadCompletedEventArgs>(MyDownloadFileAsyncCompleted); 
   spClient.DownloadFileAsync(sourceDocumentUri, tempFileName, wait); 
 
   // Wait till the operation completes 
   wait.WaitOne(); 
   wait.Close(); 
 
   // Delete the temporary file we created 
   File.Delete(tempFileName); 
} 
 
private static void MyDownloadFileAsyncCompleted(object sender, SharePointClientDownloadCompletedEventArgs e) 
{ 
   // Remove our handler 
   SharePointClient spClient = sender as SharePointClient; 
   spClient.DownloadCompleted -= new EventHandler<SharePointClientDownloadCompletedEventArgs>(MyDownloadFileAsyncCompleted); 
 
   if (e.Error == null && !e.Cancelled) 
   { 
      // All is OK, use RasterCodecs to get its info 
      using (RasterCodecs codecs = new RasterCodecs()) 
      { 
         using (CodecsImageInfo imageInfo = codecs.GetInformation(e.DestinationFileName, true)) 
         { 
            // Show the image info 
            Console.WriteLine("URL:        {0}", e.SourceUri); 
            Console.WriteLine("Pages:      {0}", imageInfo.TotalPages); 
            Console.WriteLine("Size:       {0} by {1} pixels", imageInfo.Width, imageInfo.Height); 
            Console.WriteLine("Resolution: {0} by {1} dpi", imageInfo.XResolution, imageInfo.YResolution); 
            Console.WriteLine("Bits/Pixel: {0}", imageInfo.BitsPerPixel); 
         } 
      } 
   } 
   else 
   { 
      // Some error occured 
      if (e.Error != null) 
         Console.WriteLine(e.Error.Message); 
      else 
         Console.WriteLine("User cancelled"); 
   } 
 
   // Tell whoever is listening that we are done 
   EventWaitHandle wait = e.UserState as EventWaitHandle; 
   wait.Set(); 
} 
Requirements

Target Platforms

Help Version 23.0.2024.8.6
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© 1991-2024 LEAD Technologies, Inc. All Rights Reserved.
Products | Support | Contact Us | Intellectual Property Notices
© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.