Question

我是node.js的菜鸟，按照＆＃34; Node.js in action＆＃34;中的示例进行操作。我有一个关于一个例子的问题：以下代码通过telnet实现一个简单的聊天服务器。当我写一条消息时，脚本应该向所有连接的客户端发送消息。

var events = require('events');
var net = require('net');

var channel = new events.EventEmitter();
channel.clients = {};
channel.subscriptions = {};

channel.on('join',function(id,client){
    this.clients[id] = client;
    this.subscriptions[id] = function(senderId,message){
        if(id != senderId){
            this.clients[id].write(message);
        }
    };
    this.on('broadcast',this.subscriptions);
});

var server = net.createServer(function(client){
    var id = client.remoteAddress+':'+client.remotePort;

    client.on('connect',function(){
        channel.emit('join',id,client);
    });

    client.on('data',function(data){
        data = data.toString();
        channel.emit('broadcast',id,data);
    });
});
server.listen(8888);

但是当我尝试通过telnet连接并发送消息时，它无法正常工作。谢谢

Answer 1

我注意到了几个问题。请参阅代码中的注释。

var events = require('events');
var net = require('net');

var channel = new events.EventEmitter();
channel.clients = {};
channel.subscriptions = {};

channel.on('join',function(id, client) {
    this.clients[id] = client;
    this.subscriptions[id] = function(senderId,message) {
        if(id != senderId)
            this.clients[id].write(message);
    };

    //added [id] to "this.subscriptions"
    //Before you were passing in the object this.subscriptions
    //which is not a function. So that would have actually thrown an exception.
    this.on('broadcast',this.subscriptions[id]);
});

var server = net.createServer(function(client) {
    //This function is called whenever a client connects.
    //So there is no "connect" event on the client object.
    var id = client.remoteAddress+':'+client.remotePort;
    channel.emit('join', id, client);

    client.on('data',function(data) {
        data = data.toString();
        channel.emit('broadcast',id,data);
    });
});
server.listen(8888);

另请注意：如果客户端断开连接而另一个客户端发送消息，则this.clients[id].write(message);将引发异常。这是因为，截至目前，您还没有收听断开连接事件并删除不再连接的客户端。因此，您将尝试写入不再连接的客户端，这将抛出异常。我假设你还没有到达那里，但我想提一下。

node.js eventListener不听

1 个答案: