electron/docs-translations/zh-CN/api/remote.md

remote

remote 模块提供了一种在渲染进程（网页）和主进程之间进行进程间通讯（IPC）的简便途径。

Electron中, 与GUI相关的模块（如 dialog, menu 等)只存在于主进程，而不在渲染进程中 。为了能从渲染进程中使用它们，需要用ipc模块来给主进程发送进程间消息。使用 remote 模块，可以调用主进程对象的方法，而无需显式地发送进程间消息，这类似于 Java 的 RMI。 下面是从渲染进程创建一个浏览器窗口的例子：

const remote = require('electron').remote;
const BrowserWindow = remote.BrowserWindow;

var win = new BrowserWindow({ width: 800, height: 600 });
win.loadURL('https://github.com');

注意: 反向操作（从主进程访问渲染进程），可以使用webContents.executeJavascript.

远程对象

remote模块返回的每个对象（包括函数）都代表了主进程中的一个对象（我们称之为远程对象或者远程函数）。 当调用远程对象的方法、执行远程函数或者使用远程构造器（函数）创建新对象时，其实就是在发送同步的进程间消息。

在上面的例子中， BrowserWindow 和 win 都是远程对象，然而 new BrowserWindow 并没有在渲染进程中创建 BrowserWindow 对象。 而是在主进程中创建了 BrowserWindow 对象，并在渲染进程中返回了对应的远程对象，即 win 对象。

请注意只有 可枚举属性 才能通过 remote 进行访问.

远程对象的生命周期

Electron 确保在渲染进程中的远程对象存在（换句话说，没有被垃圾收集），那主进程中的对应对象也不会被释放。 当远程对象被垃圾收集之后，主进程中的对应对象才会被取消关联。

如果远程对象在渲染进程泄露了（即，存在某个表中但永远不会释放），那么主进程中的对应对象也一样会泄露， 所以你必须小心不要泄露了远程对象。If the remote object is leaked in the renderer process (e.g. stored in a map but never freed), the corresponding object in the main process will also be leaked, so you should be very careful not to leak remote objects.

不过，主要的值类型如字符串和数字，是传递的副本。

给主进程传递回调函数

在主进程中的代码可以从渲染进程——remote模块——中接受回调函数，但是使用这个功能的时候必须非常非常小心。Code in the main process can accept callbacks from the renderer - for instance the remote module - but you should be extremely careful when using this feature.

首先，为了避免死锁，传递给主进程的回调函数会进行异步调用。所以不能期望主进程来获得传递过去的回调函数的返回值。First, in order to avoid deadlocks, the callbacks passed to the main process are called asynchronously. You should not expect the main process to get the return value of the passed callbacks.

比如，在渲染进程For instance you can't use a function from the renderer process in an Array.map called in the main process:

// 主进程 mapNumbers.js
exports.withRendererCallback = function(mapper) {
  return [1,2,3].map(mapper);
}

exports.withLocalCallback = function() {
  return exports.mapNumbers(function(x) {
    return x + 1;
  });
}

// 渲染进程
var mapNumbers = require("remote").require("./mapNumbers");

var withRendererCb = mapNumbers.withRendererCallback(function(x) {
  return x + 1;
})

var withLocalCb = mapNumbers.withLocalCallback()

console.log(withRendererCb, withLocalCb) // [true, true, true], [2, 3, 4]

As you can see, the renderer callback's synchronous return value was not as expected, and didn't match the return value of an identical callback that lives in the main process.

Second, the callbacks passed to the main process will persist until the main process garbage-collects them.

For example, the following code seems innocent at first glance. It installs a callback for the close event on a remote object:

remote.getCurrentWindow().on('close', function() {
  // blabla...
});

But remember the callback is referenced by the main process until you explicitly uninstall it. If you do not, each time you reload your window the callback will be installed again, leaking one callback for each restart.

To make things worse, since the context of previously installed callbacks has been released, exceptions will be raised in the main process when the close event is emitted.

To avoid this problem, ensure you clean up any references to renderer callbacks passed to the main process. This involves cleaning up event handlers, or ensuring the main process is explicitly told to deference callbacks that came from a renderer process that is exiting.

Accessing built-in modules in the main process

The built-in modules in the main process are added as getters in the remote module, so you can use them directly like the electron module.

const app = remote.app;

方法

remote 模块有以下方法：

remote.require(module)

• module String

返回在主进程中执行 require(module) 所返回的对象。

remote.getCurrentWindow()

返回该网页所属的 BrowserWindow 对象。

remote.getCurrentWebContents()

返回该网页的 WebContents 对象

remote.getGlobal(name)

• name String

返回在主进程中名为 name 的全局变量(即 global[name]) 。

remote.process

返回主进程中的 process 对象。等同于 remote.getGlobal('process') 但是有缓存。