Node.js Net模塊和DNS模塊

net模塊用于底層的網(wǎng)絡(luò)通信。

服務(wù)器端Socket接口

下面代碼打開一個服務(wù)器端Socket接口，用來接受客戶端的數(shù)據(jù)。

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(wù)端，一旦收到客戶端發(fā)送的數(shù)據(jù)，就發(fā)出回應(yīng)，同時還監(jiān)聽客戶端是否中斷通信。最后，listen方法打開服務(wù)端。

客戶端Socket接口

客戶端Socket接口用來向服務(wù)器發(fā)送數(shù)據(jù)。

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(wù)器之后，就向服務(wù)器發(fā)送數(shù)據(jù)，然后監(jiān)聽服務(wù)器返回的數(shù)據(jù)。

DNS模塊

DNS模塊用于解析域名。resolve4方法用于IPv4環(huán)境，resolve6方法用于IPv6環(huán)境，lookup方法在以上兩種環(huán)境都可以使用，返回IP地址（address）和當(dāng)前環(huán)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));
});