net模塊用于底層的網絡通信。 [TOC] ## 服務器端Socket接口 下面代碼打開一個服務器端Socket接口，用來接受客戶端的數據。 ~~~ 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); }); ~~~ 上面代碼中，createServer方法建立了一個服務端，一旦收到客戶端發送的數據，就發出回應，同時還監聽客戶端是否中斷通信。最后，listen方法打開服務端。 ## 客戶端Socket接口 客戶端Socket接口用來向服務器發送數據。 ~~~ 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'); }); ~~~ 上面代碼連接服務器之后，就向服務器發送數據，然后監聽服務器返回的數據。 ## DNS模塊 DNS模塊用于解析域名。resolve4方法用于IPv4環境，resolve6方法用于IPv6環境，lookup方法在以上兩種環境都可以使用，返回IP地址（address）和當前環境（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)); }); ~~~