protocol
- Using protocol with a custom partition or session
- 方法

protocol

注册自定义协议并拦截基于现有协议的请求。

实现与 file:// 协议具有相同效果的协议的示例:

const { app, protocol } = require('electron')
const path = require('path')
app.whenReady().then(() => {
  protocol.registerFileProtocol('atom', (request, callback) => {
    const url = request.url.substr(7)
    callback({ path: path.normalize(`${__dirname}/${url}`) })
  })
})

注意: 除了指定的方法, 其他方法只能在 app 模块的 ready 事件被触发后使用。

Using `protocol` with a custom `partition` or `session`

A protocol is registered to a specific Electron session object. If you don’t specify a session, then your protocol will be applied to the default session that Electron uses. However, if you define a partition or session on your browserWindow‘s webPreferences, then that window will use a different session and your custom protocol will not work if you just use electron.protocol.XXX.

To have your custom protocol work in combination with a custom session, you need to register it to that session explicitly.

const { session, app, protocol } = require('electron')
const path = require('path')
app.whenReady().then(() => {
  const partition = 'persist:example'
  const ses = session.fromPartition(partition)
  ses.protocol.registerFileProtocol('atom', (request, callback) => {
    const url = request.url.substr(7)
    callback({ path: path.normalize(`${__dirname}/${url}`) })
  })
  mainWindow = new BrowserWindow({ webPreferences: { partition } })
})

方法

protocol 模块具有以下方法：

`protocol.registerSchemesAsPrivileged(customSchemes)`

customSchemes CustomScheme[]

注意. 此方法只能在 app 的 ready 事件触发前调用，且只能调用一次

Registers the scheme as standard, secure, bypasses content security policy for resources, allows registering ServiceWorker, supports fetch API, and streaming video/audio. Specify a privilege with the value of true to enable the capability.

An example of registering a privileged scheme, that bypasses Content Security Policy:

const { protocol } = require('electron')
protocol.registerSchemesAsPrivileged([
  { scheme: 'foo', privileges: { bypassCSP: true } }
])

标准scheme遵循 RFC 3986 所设定的 URI泛型语法。例如, http 和 https 是标准协议, 而 file 不是。

Registering a scheme as standard allows relative and absolute resources to be resolved correctly when served. 否则, 该协议将表现为 file 协议, 而且，这种文件协议将不能解析相对路径。

例如, 当您使用自定义协议加载以下内容时，如果你不将其注册为标准scheme, 图片将不会被加载, 因为非标准scheme无法识别相对路径:

<body>
  <img src='test.png'>
</body>

注册一个scheme作为标准scheme将允许其通过FileSystem 接口访问文件。否则, 渲染器将会因为该scheme，而抛出一个安全性错误。

By default web storage apis (localStorage, sessionStorage, webSQL, indexedDB, cookies) are disabled for non standard schemes. So in general if you want to register a custom protocol to replace the http protocol, you have to register it as a standard scheme.

Protocols that use streams (http and stream protocols) should set stream: true. The <video> and <audio> HTML elements expect protocols to buffer their responses by default. The stream flag configures those elements to correctly expect streaming responses.

`protocol.registerFileProtocol(scheme, handler)`

scheme String
handler 函数
- request ProtocolRequest
- callback Function
  - response (String | ProtocolResponse)

Returns Boolean - Whether the protocol was successfully registered

Registers a protocol of scheme that will send a file as the response. The handler will be called with request and callback where request is an incoming request for the scheme.

要处理 request, 应当使用文件的路径或具有 path 属性的对象来调用 callback。例如:callback(filePath)或 callback({ path: filePath }). The filePath must be an absolute path.

By default the scheme is treated like http:, which is parsed differently from protocols that follow the “generic URI syntax” like file:.

`protocol.registerBufferProtocol(scheme, handler)`

scheme String
handler 函数
- request ProtocolRequest
- callback Function
  - response (Buffer | ProtocolResponse)

Returns Boolean - Whether the protocol was successfully registered

注册一个 scheme 协议, 将 Buffer作为响应发送

The usage is the same with registerFileProtocol, except that the callback should be called with either a Buffer object or an object that has the data property.

示例：

protocol.registerBufferProtocol('atom', (request, callback) => {
  callback({ mimeType: 'text/html', data: Buffer.from('<h5>Response</h5>') })
})

`protocol.registerStringProtocol(scheme, handler)`

scheme String
handler 函数
- request ProtocolRequest
- callback Function
  - response (String | ProtocolResponse)

Returns Boolean - Whether the protocol was successfully registered

注册一个 scheme 协议, 将 String 作为响应发送

The usage is the same with registerFileProtocol, except that the callback should be called with either a String or an object that has the data property.

`protocol.registerHttpProtocol(scheme, handler)`

scheme String
handler 函数
- request ProtocolRequest
- callback Function
  - response ProtocolResponse

Returns Boolean - Whether the protocol was successfully registered

注册一个 scheme 协议, 将 HTTP 请求作为响应发送

The usage is the same with registerFileProtocol, except that the callback should be called with an object that has the url property.

`protocol.registerStreamProtocol(scheme, handler)`

scheme String
handler 函数
- request ProtocolRequest
- callback Function
  - response (ReadableStream | ProtocolResponse)

Returns Boolean - Whether the protocol was successfully registered

Registers a protocol of scheme that will send a stream as a response.

The usage is the same with registerFileProtocol, except that the callback should be called with either a ReadableStream object or an object that has the data property.

示例：

const { protocol } = require('electron')
const { PassThrough } = require('stream')
function createStream (text) {
  const rv = new PassThrough() // PassThrough is also a Readable stream
  rv.push(text)
  rv.push(null)
  return rv
}
protocol.registerStreamProtocol('atom', (request, callback) => {
  callback({
    statusCode: 200,
    headers: {
      'content-type': 'text/html'
    },
    data: createStream('<h5>Response</h5>')
  })
})

It is possible to pass any object that implements the readable stream API (emits data/end/error events). For example, here’s how a file could be returned:

protocol.registerStreamProtocol('atom', (request, callback) => {
  callback(fs.createReadStream('index.html'))
})

`protocol.unregisterProtocol(scheme)`

scheme String

Returns Boolean - Whether the protocol was successfully unregistered

取消对自定义scheme的注册

`protocol.isProtocolRegistered(scheme)`

scheme String

Returns Boolean - Whether scheme is already registered.