ipcMain

从主进程到渲染进程的异步通信。

进程：主进程

ipcRenderer 是一个 EventEmitter 的实例。 当在主进程中使用时，它处理从渲染器进程（网页）发送出来的异步和同步信息。 从渲染器进程发送的消息将被发送到该模块。

发送消息

也可以从主进程向渲染进程发送消息，查阅ebContents.send获取更多信息。

• 发送消息时，事件名称为channel 。
• 回复同步信息时，需要设置event.returnValue。
• 可以使用event.reply(...)将异步消息发送回发送者。 This helper method will automatically handle messages coming from frames that aren’t the main frame (e.g. iframes) whereas event.sender.send(...) will always send to the main frame.

下面是在渲染和主进程之间发送和处理消息的一个例子：

// 在主进程中.
const { ipcMain } = require('electron')
ipcMain.on('asynchronous-message', (event, arg) => {
  console.log(arg) // prints "ping"
  event.reply('asynchronous-reply', 'pong')
})
ipcMain.on('synchronous-message', (event, arg) => {
  console.log(arg) // prints "ping"
  event.returnValue = 'pong'
})

//在渲染器进程 (网页) 中。
// NB. Electron APIs are only accessible from preload, unless contextIsolation is disabled.
// See https://www.electronjs.org/docs/tutorial/process-model#preload-scripts for more details.
const { ipcRenderer } = require('electron')
console.log(ipcRenderer.sendSync('synchronous-message', 'ping')) // prints "pong"
ipcRenderer.on('asynchronous-reply', (event, arg) => {
  console.log(arg) // prints "pong"
})
ipcRenderer.send('asynchronous-message', 'ping')

方法

IpcMain模块有以下方法来侦听事件：

ipcMain.on(channel, listener)

• channel String
• listener Function
  • event IpcMainEvent
  • ...args any[]

监听 channel, 当新消息到达，将通过 listener(event, args…) 调用 listener。

ipcMain.once(channel, listener)

• channel String
• listener Function
  • event IpcMainEvent
  • ...args any[]

添加一次性 listener 函数。 这个 listener 只会在 channel下一次收到消息的时候被调用，之后这个监听器会被移除。

ipcMain.removeListener(channel, listener)

• channel String
• listener Function
  • ...args any[]

为特定的 channel 从监听队列中删除特定的 listener 监听者.

ipcMain.removeAllListeners([channel])

• channel String (optional)

移除所有指定 channel 的监听器； 若未指定 channel，则移除所有监听器。

ipcMain.handle(channel, listener)

• channel String

• listener Function<Promise\ | any>

  • event IpcMainInvokeEvent
  • ...args any[]

为一个 invokeable的IPC 添加一个handler。 每当一个渲染进程调用 ipcRenderer.invoke(channel, ...args) 时这个处理器就会被调用。

If listener returns a Promise, the eventual result of the promise will be returned as a reply to the remote caller. Otherwise, the return value of the listener will be used as the value of the reply.

// Main process
ipcMain.handle('my-invokable-ipc', async (event, ...args) => {
  const result = await somePromise(...args)
  return result
})
// Renderer process
async () => {
  const result = await ipcRenderer.invoke('my-invokable-ipc', arg1, arg2)
  // ...
}

The event that is passed as the first argument to the handler is the same as that passed to a regular event listener. It includes information about which WebContents is the source of the invoke request.

Errors thrown through handle in the main process are not transparent as they are serialized and only the message property from the original error is provided to the renderer process. Please refer to #24427 for details.

ipcMain.handleOnce(channel, listener)

• channel String

• listener Function<Promise\ | any>

  • event IpcMainInvokeEvent
  • ...args any[]

Handles a single invokeable IPC message, then removes the listener. See ipcMain.handle(channel, listener).

ipcMain.removeHandler(channel)

• channel String

Removes any handler for channel, if present.

IpcMainEvent object

The documentation for the event object passed to the callback can be found in the ipc-main-event structure docs.

IpcMainInvokeEvent object

The documentation for the event object passed to handle callbacks can be found in the ipc-main-invoke-event structure docs.