Managing Downloads

To provide the user access to Internet resources, you must learn how to manage download operations:

1. Create an instance of the DownloadRequest interface that defines the URL of the file to be downloaded:

   var downloadRequest = new webapis.DownloadRequest("http://www.samsung.com/index.html", "downloads");
   

   The final parameter (downloads) defines the folder where the downloaded content is stored. The parameter uses a relative folder location defined in the Filesystem API. The folder is not an absolute folder location, but instead uses a virtual root location (downloads is the default download location in the virtual root).

2. Define the event handlers for different download process notifications using the DownloadCallback listener interface:

   var listener = 
   {
      /* When the download progresses (interval is platform-dependent) */
      onprogress: function(id, receivedSize, totalSize) 
      {
         console.log('Received with id: ' + id + ', ' + receivedSize + '/' + totalSize);
      },
   
      /* When the user pauses the download */
      onpaused: function(id) 
      {
         console.log('Paused with id: ' + id);
      },
   
      /* When the user cancels the download */
      oncanceled: function(id) 
      {
         console.log('Canceled with id: ' + id);
      },
   
      /* When the download is completed */
      oncompleted: function(id, fullPath) 
      {
         console.log('Completed with id: ' + id + ', full path: ' + fullPath);
      },
   
      /* When the download fails */
      onfailed: function(id, error) 
      {
         console.log('Failed with id: ' + id + ', error name: ' + error.name);
      }
   };

3. To start the download of the HTML file from the Internet, use the start() method of the DownloadManager interface:

   downloadId = webapis.download.start(downloadRequest, listener);
   

   The start() method returns a unique identifier for the download operation.

4. During the download:

   1. To pause the download, use the pause() method with the download ID:

      webapis.download.pause(downloadId);
      

   2. To resume the download, use the resume() method with the download ID:

      webapis.download.resume(downloadId);
      

   3. To cancel the download, use the cancel() method with the download ID:

      webapis.download.cancel(downloadId);