nodejs学习

代码

var http = require('http');
http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello World
');
}).listen(1337, '127.0.0.1');
console.log('Server running at http://127.0.0.1:1337/');

% node example.js
Server running at http://127.0.0.1:1337/

Here is an example of a simple TCP server which listens on port 1337 and echoes whatever you send it:

var net = require('net');

var server = net.createServer(function (socket) {
  socket.write('Echo server
');
  socket.pipe(socket);
});

server.listen(1337, '127.0.0.1');

// these modules need to be imported in order to use them.
// Node has several modules.  They are like any #include
// or import statement in other languages
var http = require("http");
var url = require("url");

// The most important line in any Node file.  This function
// does the actual process of creating the server.  Technically,
// Node tells the underlying operating system that whenever a
// connection is made, this particular callback function should be
// executed.  Since we're creating a web service with REST API,
// we want an HTTP server, which requires the http variable
// we created in the lines above.
// Finally, you can see that the callback method receives a 'request'
// and 'response' object automatically.  This should be familiar
// to any PHP or Java programmer.
http.createServer(function(request, response) {

     // The response needs to handle all the headers, and the return codes
     // These types of things are handled automatically in server programs
     // like Apache and Tomcat, but Node requires everything to be done yourself
     response.writeHead(200, {"Content-Type": "text/plain"});

     // Here is some unique-looking code.  This is how Node retrives
     // parameters passed in from client requests.  The url module
     // handles all these functions.  The parse function
     // deconstructs the URL, and places the query key-values in the
     // query object.  We can find the value for the "number" key
     // by referencing it directly - the beauty of JavaScript.
     var params = url.parse(request.url, true).query;
     var input = params.number;

     // These are the generic JavaScript methods that will create
     // our random number that gets passed back to the caller
     var numInput = new Number(input);
     var numOutput = new Number(Math.random() * numInput).toFixed(0);
     
     // Write the random number to response
     response.write(numOutput);
     
     // Node requires us to explicitly end this connection.  This is because
     // Node allows you to keep a connection open and pass data back and forth,
     // though that advanced topic isn't discussed in this article.
     response.end();

   // When we create the server, we have to explicitly connect the HTTP server to
   // a port.  Standard HTTP port is 80, so we'll connect it to that one.
}).listen(80);

// Output a String to the console once the server starts up, letting us know everything
// starts up correctly
console.log("Random Number Generator Running...");

一个聊天服务器允许多个客户端连接到它。每个客户端都可以编写消息，然后广播给所有其他用户。下面给出了最简单的聊天服务器的代码。

net = require('net');

var sockets = [];

var s = net.Server(function(socket) {

    sockets.push(socket);

    socket.on('data', function(d) {

        for (var i=0; i < sockets.length; i++ ) {
            sockets[i].write(d);
        }
    });
});

s.listen(8001);

下面的源代码（在下载示例文件中叫做 chat2.js ）是一个经过改进的套接字服务器，其功能有所增强，能够处理“糟糕的情况”（比如客户端断开）。

net = require('net');

var sockets = [];
var name_map = new Array();
var chuck_quotes = [
    "There used to be a street named after Chuck Norris, but it was changed because 
     nobody crosses Chuck Norris and lives.",
    "Chuck Norris died 20 years ago, Death just hasn't built up the courage to tell 
     him yet.",
    "Chuck Norris has already been to Mars; that's why there are no signs of life.",
    "Some magicians can walk on water, Chuck Norris can swim through land.",
    "Chuck Norris and Superman once fought each other on a bet. The loser had to start 
     wearing his underwear on the outside of his pants."
]

function get_username(socket) {
    var name = socket.remoteAddress;
    for (var k in name_map) {
        if (name_map[k] == socket) {
            name = k;
        }
    }
    return name;
}

function delete_user(socket) {
    var old_name = get_username(socket);
    if (old_name != null) {
        delete(name_map[old_name]);
    }
}

function send_to_all(message, from_socket, ignore_header) {
    username = get_username(from_socket);
    for (var i=0; i < sockets.length; i++ ) {
        if (from_socket != sockets[i]) {
            if (ignore_header) {
                send_to_socket(sockets[i], message);
            }
            else {
                send_to_socket(sockets[i], username + ': ' + message);
            }
        }
    }
}

function send_to_socket(socket, message) {
    socket.write(message + '
');
}

function execute_command(socket, command, args) {
    if (command == 'identify') {
        delete_user(socket);
        name = args.split(' ', 1)[0];
        name_map[name] = socket;
    }
    if (command == 'me') {
        name = get_username(socket);
        send_to_all('**' + name + '** ' + args, socket, true);
    }
    if (command == 'chuck') {
        var i = Math.floor(Math.random() * chuck_quotes.length);
        send_to_all(chuck_quotes[i], socket, true);
    }
    if (command == 'who') {
        send_to_socket(socket, 'Identified users:');
        for (var name in name_map) {
            send_to_socket(socket, '- ' + name);
        }
    }
}

function send_private_message(socket, recipient_name, message) {
    to_socket = name_map[recipient_name];
    if (! to_socket) {
        send_to_socket(socket, recipient_name + ' is not a valid user');
        return;
    }
    send_to_socket(to_socket, '[ DM ' + get_username(socket) + ' ]: ' + message);
}

var s = net.Server(function(socket) {
    sockets.push(socket);
    socket.on('data', function(d) {
        data = d.toString('utf8').trim();
        // check if it is a command
        var cmd_re = /^/([a-z]+)[ ]*(.*)/g;
        var dm_re = /^@([a-z]+)[ ]+(.*)/g;
        cmd_match = cmd_re.exec(data)
        dm_match = dm_re.exec(data)
        if (cmd_match) {
            var command = cmd_match[1];
            var args = cmd_match[2];
            execute_command(socket, command, args);
        }
        // check if it is a direct message
        else if (dm_match) {
            var recipient = dm_match[1];
            var message = dm_match[2];
            send_private_message(socket, recipient, message);
        }
        // if none of the above, send to all
        else {
            send_to_all(data, socket);
        };

    });
    socket.on('close', function() {
        sockets.splice(sockets.indexOf(socket), 1);
        delete_user(socket);
    });
});
s.listen(8001);