ipcMain

从主进程到渲染进程的异步通信。

线程：主线程

The ipcMain module is an Event Emitter. 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

It is also possible to send messages from the main process to the renderer process, see webContents.send for more information.

• 发送消息时，事件名称为channel。
• 回复同步信息时，需要设置event.returnValue。
• To send an asynchronous message back to the sender, you can use event.reply(...). 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。
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 - 回调函数
  • event IpcMainEvent
  • ...args any[]

监听 channel，当接收到新的消息时 listener 会以 listener(event, args...) 的形式被调用。

ipcMain.once(channel, listener)

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

添加一次性的 listener。当且仅当下一个消息发送到 channel 时 listener 才会被调用，随后 <0>listener 会被移除。

ipcMain.removeListener(channel, listener)

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

从监听器数组中移除监听 channel 的指定 listener。

ipcMain.removeAllListeners([channel])

• channel String (optional)

删除所有监听者，或特指的 channel 的所有监听者.

ipcMain.handle(channel, listener)

• channel String
• listener Function | any>
  • event IpcMainInvokeEvent
  • ...args any[]

Adds a handler for an invokeable IPC. This handler will be called whenever a renderer calls ipcRenderer.invoke(channel, ...args).

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.

ipcMain.handleOnce(channel, listener)

• channel String
• listener Function | 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.