net模块用于底层的网络通信。 [TOC] ## 服务器端Socket接口 下面代码打开一个服务器端Socket接口，用来接受客户端的数据。 ~~~ var serverPort = 9099; var net = require('net'); var server = net.createServer(function(client) { console.log('client connected'); console.log('client IP Address: ' + client.remoteAddress); console.log('is IPv6: ' + net.isIPv6(client.remoteAddress)); console.log('total server connections: ' + server.connections); // Waiting for data from the client. client.on('data', function(data) { console.log('received data: ' + data.toString()); // Write data to the client socket. client.write('hello from server'); }); // Closed socket event from the client. client.on('end', function() { console.log('client disconnected'); }); }); server.on('error',function(err){ console.log(err); server.close(); }); server.listen(serverPort, function() { console.log('server started on port ' + serverPort); }); ~~~ 上面代码中，createServer方法建立了一个服务端，一旦收到客户端发送的数据，就发出回应，同时还监听客户端是否中断通信。最后，listen方法打开服务端。 ## 客户端Socket接口 客户端Socket接口用来向服务器发送数据。 ~~~ var serverPort = 9099; var server = 'localhost'; var net = require('net'); console.log('connecting to server...'); var client = net.connect({server:server,port:serverPort},function(){ console.log('client connected'); // send data console.log('send data to server'); client.write('greeting from client socket'); }); client.on('data', function(data) { console.log('received data: ' + data.toString()); client.end(); }); client.on('error',function(err){ console.log(err); }); client.on('end', function() { console.log('client disconnected'); }); ~~~ 上面代码连接服务器之后，就向服务器发送数据，然后监听服务器返回的数据。 ## DNS模块 DNS模块用于解析域名。resolve4方法用于IPv4环境，resolve6方法用于IPv6环境，lookup方法在以上两种环境都可以使用，返回IP地址（address）和当前环境（IPv4或IPv6）。 ~~~ var dns = require('dns'); dns.resolve4('www.pecollege.net', function (err, addresses) { if (err) console.log(err); console.log('addresses: ' + JSON.stringify(addresses)); }); dns.lookup('www.pecollege.net', function (err, address, family) { if (err) console.log(err); console.log('addresses: ' + JSON.stringify(address)); console.log('family: ' + JSON.stringify(family)); }); ~~~