适配器
适配器
In some cases you might not want to use socket.io. It's not a problem. Nest allows you to use any other websockets library, you only have to create an adapter. Let's imagine that you want to use ws. We have to create a class, which implements WebSocketAdapter (@nestjs/common) interface:
在某些情况下你可能不想使用socket.io
。没问题,Nest允许你使用任何其他的websockets
库,使用其他库时,你只需要创建一个适配器就可以了。
我们来以ws
作为一个例子。 我们需要创建一个可以实现websocketadapter
(@ nestjs /普通)接口的类:
export interface WebSocketAdapter {
create(port: number);
createWithNamespace?(port: number, namespace: string);
bindClientConnect(server, callback: (...args) => void);
bindClientDisconnect?(client, callback: (...args) => void);
bindMessageHandlers(client, handlers: MessageMappingProperties[]);
bindMiddleware?(server, middleware: (socket, next) => void);
}
Three methods are obligatory - create, bindClientConnect and bindMessageHandlers. The rest are optional. Take a look at the example:
create
, bindClientConnect
和 bindMessageHandlers
这三种方法是必须的,其他都是可选的。请看如下示例:
import * as WebSocket from 'ws';
import { WebSocketAdapter } from '@nestjs/common';
import { MessageMappingProperties } from '@nestjs/websockets';
class WsAdapter implements WebSocketAdapter {
public create(port: number) {
return new WebSocket.Server({ port });
}
public bindClientConnect(server, callback: (...args: any[]) => void) {
server.on('connection', callback);
}
public bindMessageHandlers(client, handlers: MessageMappingProperties[]) {
client.on('message', (buffer) => {
const data = JSON.parse(buffer);
const { type } = data;
const messageHandler = handlers.find((handler) => handler.message === type);
messageHandler && messageHandler.callback(data);
});
}
}
The most interesting is bindMessageHandlers function, where we have to bind messages to appropriate handlers. Handler is an object, with message property (passed in @SubscribeMessage() decorator) and callback (function to execute). I decided to recognize messages by type property, but it's your decision how you want to map them. The last step - we must set-up our adapter:
最有趣的是bindmessagehandlers
功能,在该功能中我们必须将消息和对应的处理程序结合起来。Handler
是一个有消息属性( @SubscribeMessage()
装饰器中传递)和回调函数(执行函数)的对象。我决定通过type
属性识别消息,你可以选择使用其他映射方式。 最后一步--我们必须设置我们的适配器:
const app = NestFactory.create(ApplicationModule);
app.useWebSocketAdapter(new WsAdapter());
That's it!
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