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Class: DownloadItem

Class: DownloadItem

Control file downloads from remote sources.

Process: Main
This class is not exported from the 'electron' module. It is only available as a return value of other methods in the Electron API.

DownloadItem is an EventEmitter that represents a download item in Electron. It is used in will-download event of Session class, and allows users to control the download item.

// Im Hauptprozess.
const { BrowserWindow } = require('electron')
const win = new BrowserWindow()
win.webContents.session.on('will-download', (event, item, webContents) => {
// Set the save path, making Electron not to prompt a save dialog.
item.setSavePath('/tmp/save.pdf')

item.on('updated', (event, state) => {
if (state === 'interrupted') {
console.log('Download is interrupted but can be resumed')
} else if (state === 'progressing') {
if (item.isPaused()) {
console.log('Download is paused')
} else {
console.log(`Received bytes: ${item.getReceivedBytes()}`)
}
}
})
item.once('done', (event, state) => {
if (state === 'completed') {
console.log('Download successfully')
} else {
console.log(`Download failed: ${state}`)
}
})
})

Instanz-Ereignisse

Event: 'updated'

Kehrt zurück:

  • event Event
  • state String - Can be progressing or interrupted.

Ausgelöst, wenn sich der Status des Downloads geändert hat, aber der Download nicht fertig ist.

The state can be one of following:

  • progressing - The download is in-progress.
  • interrupted - The download has interrupted and can be resumed.

Event: 'done'

Kehrt zurück:

  • event Event
  • state String - Can be completed, cancelled or interrupted.

Ausgelöst, wenn der Download beendet wurde. This includes a completed download, a cancelled download (via downloadItem.cancel()), and interrupted download that can't be resumed.

The state can be one of following:

  • completed - The download completed successfully.
  • cancelled - The download has been cancelled.
  • interrupted - The download has interrupted and can not resume.

Beispiel Methoden

The downloadItem object has the following methods:

downloadItem.setSavePath(path)

  • path String - Set the save file path of the download item.

The API is only available in session's will-download callback function. If path doesn't exist, Electron will try to make the directory recursively. If user doesn't set the save path via the API, Electron will use the original routine to determine the save path; this usually prompts a save dialog.

downloadItem.getSavePath()

Returns String - The save path of the download item. This will be either the path set via downloadItem.setSavePath(path) or the path selected from the shown save dialog.

downloadItem.setSaveDialogOptions(options)

  • options SaveDialogOptions - Set the save file dialog options. This object has the same properties as the options parameter of dialog.showSaveDialog().

This API allows the user to set custom options for the save dialog that opens for the download item by default. The API is only available in session's will-download callback function.

downloadItem.getSaveDialogOptions()

Returns SaveDialogOptions - Returns the object previously set by downloadItem.setSaveDialogOptions(options).

downloadItem.pause()

Pauses the download.

downloadItem.isPaused()

Returns Boolean - Whether the download is paused.

downloadItem.resume()

Resumes the download that has been paused.

Note: To enable resumable downloads the server you are downloading from must support range requests and provide both Last-Modified and ETag header values. Otherwise resume() will dismiss previously received bytes and restart the download from the beginning.

downloadItem.canResume()

Returns Boolean - Whether the download can resume.

downloadItem.cancel()

Cancels the download operation.

downloadItem.getURL()

Returns String - The origin URL where the item is downloaded from.

downloadItem.getMimeType()

Returns String - The files mime type.

downloadItem.hasUserGesture()

Returns Boolean - Whether the download has user gesture.

downloadItem.getFilename()

Returns String - The file name of the download item.

Note: The file name is not always the same as the actual one saved in local disk. If user changes the file name in a prompted download saving dialog, the actual name of saved file will be different.

downloadItem.getTotalBytes()

Returns Integer - The total size in bytes of the download item.

If the size is unknown, it returns 0.

downloadItem.getReceivedBytes()

Returns Integer - The received bytes of the download item.

downloadItem.getContentDisposition()

Returns String - The Content-Disposition field from the response header.

downloadItem.getState()

Returns String - The current state. Can be progressing, completed, cancelled or interrupted.

Note: The following methods are useful specifically to resume a cancelled item when session is restarted.

downloadItem.getURLChain()

Returns String[] - The complete URL chain of the item including any redirects.

downloadItem.getLastModifiedTime()

Returns String - Last-Modified header value.

downloadItem.getETag()

Returns String - ETag header value.

downloadItem.getStartTime()

Returns Double - Number of seconds since the UNIX epoch when the download was started.

Instanz Eigenschaften

downloadItem.savePath

A String property that determines the save file path of the download item.

The property is only available in session's will-download callback function. If user doesn't set the save path via the property, Electron will use the original routine to determine the save path; this usually prompts a save dialog.