设备访问

类似基于 Chromium 的浏览器一样, Electron 也提供了通过 web API 访问设备硬件的方法。大部分接口就像在浏览器调用的 API 一样，但有一些差异需要考虑到。 Electron和浏览器之间的主要区别是请求访问设备时发生的情况。在浏览器中，用户可以在弹出窗口中允许访问单独的设备。在 Electron API中，提供了可供开发者自动选择设备或提示用户通过开发者创建的接口选择设备。

Web Bluetooth API

Web Bluetooth API 可以被用来连接蓝牙设备。为了在 Electron 中使用此 API ，开发者将需要处理与设备请求相关的webContent的select-bluetooth-device事件。

此外，当需要进行例如pin的额外验证时，ses.setBluetoothPairingHandler(handler)可以被用来在Windows或Linux上处理配对蓝牙设备。

示例

这个示例演示了一个 Electron 应用程序，当点击了 Test Bluetooth 按钮时，它会自动选择第一个可用的蓝牙设备。

docs/fiddles/features/web-bluetooth (36.2.0)Open in Fiddle

main.js
preload.js
index.html
renderer.js

const { app, BrowserWindow, ipcMain } = require('electron/main')
const path = require('node:path')

let bluetoothPinCallback
let selectBluetoothCallback

function createWindow () {
  const mainWindow = new BrowserWindow({
    width: 800,
    height: 600,
    webPreferences: {
      preload: path.join(__dirname, 'preload.js')
    }
  })

  mainWindow.webContents.on('select-bluetooth-device', (event, deviceList, callback) => {
    event.preventDefault()
    selectBluetoothCallback = callback
    const result = deviceList.find((device) => {
      return device.deviceName === 'test'
    })
    if (result) {
      callback(result.deviceId)
    } else {
      // The device wasn't found so we need to either wait longer (eg until the
      // device is turned on) or until the user cancels the request
    }
  })

  ipcMain.on('cancel-bluetooth-request', (event) => {
    selectBluetoothCallback('')
  })

  // Listen for a message from the renderer to get the response for the Bluetooth pairing.
  ipcMain.on('bluetooth-pairing-response', (event, response) => {
    bluetoothPinCallback(response)
  })

  mainWindow.webContents.session.setBluetoothPairingHandler((details, callback) => {
    bluetoothPinCallback = callback
    // Send a message to the renderer to prompt the user to confirm the pairing.
    mainWindow.webContents.send('bluetooth-pairing-request', details)
  })

  mainWindow.loadFile('index.html')
}

app.whenReady().then(() => {
  createWindow()

  app.on('activate', function () {
    if (BrowserWindow.getAllWindows().length === 0) createWindow()
  })
})

app.on('window-all-closed', function () {
  if (process.platform !== 'darwin') app.quit()
})

const { contextBridge, ipcRenderer } = require('electron/renderer')

contextBridge.exposeInMainWorld('electronAPI', {
  cancelBluetoothRequest: () => ipcRenderer.send('cancel-bluetooth-request'),
  bluetoothPairingRequest: (callback) => ipcRenderer.on('bluetooth-pairing-request', () => callback()),
  bluetoothPairingResponse: (response) => ipcRenderer.send('bluetooth-pairing-response', response)
})

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
    <title>Web Bluetooth API</title>
  </head>
  <body>
    <h1>Web Bluetooth API</h1>

    <button id="clickme">Test Bluetooth</button>
    <button id="cancel">Cancel Bluetooth Request</button>

    <p>Currently selected bluetooth device: <strong id="device-name"></strong></p>

    <script src="./renderer.js"></script>
  </body>
</html>

async function testIt () {
  const device = await navigator.bluetooth.requestDevice({
    acceptAllDevices: true
  })
  document.getElementById('device-name').innerHTML = device.name || `ID: ${device.id}`
}

document.getElementById('clickme').addEventListener('click', testIt)

function cancelRequest () {
  window.electronAPI.cancelBluetoothRequest()
}

document.getElementById('cancel').addEventListener('click', cancelRequest)

window.electronAPI.bluetoothPairingRequest((event, details) => {
  const response = {}

  switch (details.pairingKind) {
    case 'confirm': {
      response.confirmed = window.confirm(`Do you want to connect to device ${details.deviceId}?`)
      break
    }
    case 'confirmPin': {
      response.confirmed = window.confirm(`Does the pin ${details.pin} match the pin displayed on device ${details.deviceId}?`)
      break
    }
    case 'providePin': {
      const pin = window.prompt(`Please provide a pin for ${details.deviceId}.`)
      if (pin) {
        response.pin = pin
        response.confirmed = true
      } else {
        response.confirmed = false
      }
    }
  }

  window.electronAPI.bluetoothPairingResponse(response)
})

WebHID API

WebHID API 可以用于访问HID 设备，例如键盘和游戏机。 Electron 提供了几个使用 WebHID API的接口：

当navigator.hid.requestDevice被调用时，Session的select-hid-device事件可以用来选择一个HID设备。此外，在处理select-hid-device事件时，Session的hid-device-added和hid-device-removed事件可以用来处理设备拔插。 注意： 这些事件仅会在 select-hid-device 的回调之后被触发。它们不能作为通用HID设备监听器使用。
在第一次调用 navigator.hid.requestDevice 前, 可以通过 ses.setDevicePermissionHandler(handler) 给予设备默认权限, 此外，Electron的默认行为是在相应的WebContents的生命周期内存储已授予的设备权限。如果需要更长期的存储，开发人员可以存储设备许可信息(比如: 在处理 select-hid-device 事件时), 然后通过 setDevicePermissionHandler 从存储的信息中读取
ses.setPermissionCheckHandler(handler)可以用来禁用特定源的HID访问。

阻止列表

默认情况下，Electron 使用与 Chromium 相同的 blocklist 如果您想要覆盖此行为，您可以通过设置 disable-hid-blocklist 标志来做到这一点：

app.commandLine.appendSwitch('disable-hid-blocklist')

示例

这个例子演示了，一个Electron应用在Test WebHID按钮被点击时，自动通过ses.setDevicePermissionHandler(handler)和Session的select-hid-device事件选择HID设备。

docs/fiddles/features/web-hid (36.2.0)Open in Fiddle

main.js
index.html
renderer.js

const { app, BrowserWindow } = require('electron/main')

function createWindow () {
  const mainWindow = new BrowserWindow({
    width: 800,
    height: 600
  })

  mainWindow.webContents.session.on('select-hid-device', (event, details, callback) => {
    // Add events to handle devices being added or removed before the callback on
    // `select-hid-device` is called.
    mainWindow.webContents.session.on('hid-device-added', (event, device) => {
      console.log('hid-device-added FIRED WITH', device)
      // Optionally update details.deviceList
    })

    mainWindow.webContents.session.on('hid-device-removed', (event, device) => {
      console.log('hid-device-removed FIRED WITH', device)
      // Optionally update details.deviceList
    })

    event.preventDefault()
    if (details.deviceList && details.deviceList.length > 0) {
      callback(details.deviceList[0].deviceId)
    }
  })

  mainWindow.webContents.session.setPermissionCheckHandler((webContents, permission, requestingOrigin, details) => {
    if (permission === 'hid' && details.securityOrigin === 'file:///') {
      return true
    }
  })

  mainWindow.webContents.session.setDevicePermissionHandler((details) => {
    if (details.deviceType === 'hid' && details.origin === 'file://') {
      return true
    }
  })

  mainWindow.loadFile('index.html')
}

app.whenReady().then(() => {
  createWindow()

  app.on('activate', function () {
    if (BrowserWindow.getAllWindows().length === 0) createWindow()
  })
})

app.on('window-all-closed', function () {
  if (process.platform !== 'darwin') app.quit()
})

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
    <title>WebHID API</title>
  </head>
  <body>
    <h1>WebHID API</h1>

    <button id="clickme">Test WebHID</button>

    <h3>HID devices automatically granted access via <i>setDevicePermissionHandler</i></h3>
    <div id="granted-devices"></div>

    <h3>HID devices automatically granted access via <i>select-hid-device</i></h3>
    <div id="granted-devices2"></div>

    <script src="./renderer.js"></script>
  </body>
</html>

function formatDevices (devices) {
  return devices.map(device => device.productName).join('<hr>')
}

async function testIt () {
  document.getElementById('granted-devices').innerHTML = formatDevices(await navigator.hid.getDevices())
  document.getElementById('granted-devices2').innerHTML = formatDevices(await navigator.hid.requestDevice({ filters: [] }))
}

document.getElementById('clickme').addEventListener('click', testIt)

Web Serial API

Web Serial API 可以被用来访问串口设备比如 USB 或蓝牙。为了在Eletron中使用这个API，开发者需要处理与串口请求相关的Session的select-serial-port事件。

有几个额外的 API 用于与 Web Serial API 合作：

在处理select-serial-port事件时，Session的serial-port-added和serial-port-removed事件可以用来处理设备拔插。 注意： 这些事件仅会在 select-serial-port 的回调之后被触发。它们不能作为通用串口监听器使用。
在第一次调用 navigator.serial.requestPort 前, 可以通过 ses.setDevicePermissionHandler(handler) 给予设备默认权限, 此外，Electron的默认行为是在相应的WebContents的生命周期内存储已授予的设备权限。如果需要更长期的存储，开发人员可以存储设备许可信息(比如: 在处理 select-serial-port 事件时), 然后通过 setDevicePermissionHandler 从存储的信息中读取
ses.setPermissionCheckHandler(handler)可以用来禁用特定源的串口访问。

示例

这个例子演示了一个Eletron应用通过ses.setDevicePermissionHandler(handler)自动选择窗口设备，以及当Test Web Serial按钮被点击时通过Session的select-serial-port事件选择第一个可用的Arduino Uno串口设备（如果已连接）。

docs/fiddles/features/web-serial (36.2.0)Open in Fiddle

main.js
index.html
renderer.js

const { app, BrowserWindow } = require('electron/main')

function createWindow () {
  const mainWindow = new BrowserWindow({
    width: 800,
    height: 600
  })

  mainWindow.webContents.session.on('select-serial-port', (event, portList, webContents, callback) => {
    // Add listeners to handle ports being added or removed before the callback for `select-serial-port`
    // is called.
    mainWindow.webContents.session.on('serial-port-added', (event, port) => {
      console.log('serial-port-added FIRED WITH', port)
      // Optionally update portList to add the new port
    })

    mainWindow.webContents.session.on('serial-port-removed', (event, port) => {
      console.log('serial-port-removed FIRED WITH', port)
      // Optionally update portList to remove the port
    })

    event.preventDefault()
    if (portList && portList.length > 0) {
      callback(portList[0].portId)
    } else {
      // eslint-disable-next-line n/no-callback-literal
      callback('') // Could not find any matching devices
    }
  })

  mainWindow.webContents.session.setPermissionCheckHandler((webContents, permission, requestingOrigin, details) => {
    if (permission === 'serial' && details.securityOrigin === 'file:///') {
      return true
    }

    return false
  })

  mainWindow.webContents.session.setDevicePermissionHandler((details) => {
    if (details.deviceType === 'serial' && details.origin === 'file://') {
      return true
    }

    return false
  })

  mainWindow.loadFile('index.html')

  mainWindow.webContents.openDevTools()
}

app.whenReady().then(() => {
  createWindow()

  app.on('activate', function () {
    if (BrowserWindow.getAllWindows().length === 0) createWindow()
  })
})

app.on('window-all-closed', function () {
  if (process.platform !== 'darwin') app.quit()
})

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
    <title>Web Serial API</title>
  <body>
    <h1>Web Serial API</h1>

    <button id="clickme">Test Web Serial API</button>

    <p>Matching Arduino Uno device: <strong id="device-name""></strong></p>

    <script src="./renderer.js"></script>
  </body>
</html>

async function testIt () {
  const filters = [
    { usbVendorId: 0x2341, usbProductId: 0x0043 },
    { usbVendorId: 0x2341, usbProductId: 0x0001 }
  ]
  try {
    const port = await navigator.serial.requestPort({ filters })
    const portInfo = port.getInfo()
    document.getElementById('device-name').innerHTML = `vendorId: ${portInfo.usbVendorId} | productId: ${portInfo.usbProductId} `
  } catch (ex) {
    if (ex.name === 'NotFoundError') {
      document.getElementById('device-name').innerHTML = 'Device NOT found'
    } else {
      document.getElementById('device-name').innerHTML = ex
    }
  }
}

document.getElementById('clickme').addEventListener('click', testIt)

WebUSB API

WebUSB API 可用于访问USB设备。 Electron提供了几个与WebUSB API配合使用的API：

当navigator.usb.requestDevice被调用时，Session的select-usb-device事件可以用来选择一个USB设备。此外，在处理select-usb-device事件时，Session的usb-device-added和usb-device-removed事件可以用来处理设备拔插。 **注意：**这两个事件只有在select-usb-device的回调被调用时才会触发。它们不是设计来作为通用USB设备监听器使用的。
当 device.forget()在USB设备上被调用时，Session的usb-device-revoked事件可以用来响应。
在第一次调用 navigator.usb.requestDevice 前, 可以通过 ses.setDevicePermissionHandler(handler) 给予设备默认权限, 此外，Electron的默认行为是在相应的WebContents的生命周期内存储已授予的设备权限。如果需要长期存储，开发者可以存储授予的设备权限（如处理select-usb-device事件时），然后使用setDevicePermissionHandler从存储中读取。
ses.setPermissionCheckHandler(handler)可以用来禁用特定源的HID访问。
ses.setUSBProtectedClassesHandler可以用来允许默认不可用的受保护的USB类。

示例

这个例子演示了，一个Electron应用在Test WebUSB按钮被点击时，自动通过ses.setDevicePermissionHandler(handler)和Session的select-usb-device事件选择USB设备（如果它们已被连接）。

docs/fiddles/features/web-usb (36.2.0)Open in Fiddle

main.js
index.html
renderer.js

const { app, BrowserWindow } = require('electron/main')

function createWindow () {
  const mainWindow = new BrowserWindow({
    width: 800,
    height: 600
  })

  let grantedDeviceThroughPermHandler

  mainWindow.webContents.session.on('select-usb-device', (event, details, callback) => {
    // Add events to handle devices being added or removed before the callback on
    // `select-usb-device` is called.
    mainWindow.webContents.session.on('usb-device-added', (event, device) => {
      console.log('usb-device-added FIRED WITH', device)
      // Optionally update details.deviceList
    })

    mainWindow.webContents.session.on('usb-device-removed', (event, device) => {
      console.log('usb-device-removed FIRED WITH', device)
      // Optionally update details.deviceList
    })

    event.preventDefault()
    if (details.deviceList && details.deviceList.length > 0) {
      const deviceToReturn = details.deviceList.find((device) => {
        return !grantedDeviceThroughPermHandler || (device.deviceId !== grantedDeviceThroughPermHandler.deviceId)
      })
      if (deviceToReturn) {
        callback(deviceToReturn.deviceId)
      } else {
        callback()
      }
    }
  })

  mainWindow.webContents.session.setPermissionCheckHandler((webContents, permission, requestingOrigin, details) => {
    if (permission === 'usb' && details.securityOrigin === 'file:///') {
      return true
    }
  })

  mainWindow.webContents.session.setDevicePermissionHandler((details) => {
    if (details.deviceType === 'usb' && details.origin === 'file://') {
      if (!grantedDeviceThroughPermHandler) {
        grantedDeviceThroughPermHandler = details.device
        return true
      } else {
        return false
      }
    }
  })

  mainWindow.webContents.session.setUSBProtectedClassesHandler((details) => {
    return details.protectedClasses.filter((usbClass) => {
      // Exclude classes except for audio classes
      return usbClass.indexOf('audio') === -1
    })
  })

  mainWindow.loadFile('index.html')
}

app.whenReady().then(() => {
  createWindow()

  app.on('activate', function () {
    if (BrowserWindow.getAllWindows().length === 0) createWindow()
  })
})

app.on('window-all-closed', function () {
  if (process.platform !== 'darwin') app.quit()
})

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'">
    <title>WebUSB API</title>
  </head>
  <body>
    <h1>WebUSB API</h1>

    <button id="clickme">Test WebUSB</button>

    <h3>USB devices automatically granted access via <i>setDevicePermissionHandler</i></h3>
    <div id="granted-devices"></div>

    <h3>USB devices automatically granted access via <i>select-usb-device</i></h3>
    <div id="granted-devices2"></div>

    <script src="./renderer.js"></script>
  </body>
</html>

function getDeviceDetails (device) {
  return device.productName || `Unknown device ${device.deviceId}`
}

async function testIt () {
  const noDevicesFoundMsg = 'No devices found'
  const grantedDevices = await navigator.usb.getDevices()
  let grantedDeviceList = ''
  if (grantedDevices.length > 0) {
    for (const device of grantedDevices) {
      grantedDeviceList += `<hr>${getDeviceDetails(device)}</hr>`
    }
  } else {
    grantedDeviceList = noDevicesFoundMsg
  }
  document.getElementById('granted-devices').innerHTML = grantedDeviceList

  grantedDeviceList = ''
  try {
    const grantedDevice = await navigator.usb.requestDevice({
      filters: []
    })
    grantedDeviceList += `<hr>${getDeviceDetails(grantedDevice)}</hr>`
  } catch (ex) {
    if (ex.name === 'NotFoundError') {
      grantedDeviceList = noDevicesFoundMsg
    }
  }
  document.getElementById('granted-devices2').innerHTML = grantedDeviceList
}

document.getElementById('clickme').addEventListener('click', testIt)

Web Bluetooth API​

示例​

WebHID API​

阻止列表​

示例​

Web Serial API​

示例​

WebUSB API​

示例​

Web Bluetooth API

示例

WebHID API

阻止列表

示例

Web Serial API

示例

WebUSB API

示例