'use strict';
var fs=require('fs');
//打开一个流
var rs=fs.createReadStream('sample.txt','utf-8');
rs.on('data',function(chunk){
    console.log('DATA');
    console.log(chunk);
});
rs.on('end',function(){
    console.log('END');
});
rs.on('error',function(err){
    console.log('ERROR:'+err);
});

运行结果：
DATA
abcd
END

'use strict';
var fs = require('fs');
//在output1.txt文件中写入两行数据：
var ws1 = fs.createWriteStream('output1.txt', 'utf-8');
ws1.write('使用Stream写入文本数据...\n');
ws1.write('END.');
ws1.end();
//在output2.txt文件中写入两行数据：
var ws2 = fs.createWriteStream('output2.txt');
ws2.write(new Buffer('使用Stream写入二进制数据...\n', 'utf-8'));
ws2.write(new Buffer('END.', 'utf-8'));
ws2.end();

'use strict';
var url = require('url');
console.log(url.parse('http://user:pass@host.com:8080/path/to/file?query=string#hash'));

Url {
  protocol: 'http:',
  slashes: true,
  auth: 'user:pass',
  host: 'host.com:8080',
  port: '8080',
  hostname: 'host.com',
  hash: '#hash',
  search: '?query=string',
  query: 'query=string',
  pathname: '/path/to/file',
  path: '/path/to/file?query=string',
  href: 'http://user:pass@host.com:8080/path/to/file?query=string#hash' }

'use strict';
var path = require('path');

// 解析当前目录:
var workDir = path.resolve('.'); // '/Users/michael'

// 组合完整的文件路径:当前目录+'pub'+'index.html':
var filePath = path.join(workDir, 'pub', 'index.html');
// '/Users/michael/pub/index.html'
使用path模块可以正确处理操作系统相关的文件路径。在Windows系统下，返回的路径类似于C:\Users\michael\static\index.html，这样，我们就不关心怎么拼接路径了。
---------------------------------------------------------------------
最后，我们实现一个文件服务器file_server.js：
'use strict';
var
    fs = require('fs'),     //读写文件
    url = require('url'),   
    path = require('path'),  //组合文件路径
    http = require('http');

// 从命令行参数获取root目录，默认是当前目录:
var root = path.resolve(process.argv[2] || '.');
console.log('Static root dir: ' + root);

// 创建服务器:
var server = http.createServer(function (request, response) {
    // 获得URL的path，类似 '/css/bootstrap.css':
    var pathname = url.parse(request.url).pathname;
    // 获得对应的本地文件路径，类似 '/
    srv/www/css/bootstrap.css':
    var filepath = path.join(root, pathname);
    // 获取文件状态:
    fs.stat(filepath, function (err, stats) {
        if (!err && stats.isFile()) {
            // 没有出错并且文件存在:
            console.log('200 ' + request.url);
            // 发送200响应:
            response.writeHead(200);
            // 将文件流导向response:
            fs.createReadStream(filepath).pipe(response);
        } else {
            // 出错了或者文件不存在:
            console.log('404 ' + request.url);
            // 发送404响应:
            response.writeHead(404);
            response.end('404 Not Found');
        }
    });
});

server.listen(8080);
console.log('Server is running at http://127.0.0.1:8080/');

命令行输入：
node file_server.js /path/to/dir，把/path/to/dir改成你本地的一个有效的目录，然后在浏览器中输入http://localhost:8080/index.html：

fs=[object Object]
url=[object Object]
path=[object Object]
http=[object Object]
Static root dir:/home/lixuehe/workspace/NodeJs-
                02/home/lixuehe/workspace/JavaScript-day02/js01-lunbo
Server is running at http://192.168.196.95:8080/
request.url=/lunbo.html
pathname=/lunbo.html
filepath=/home/lixuehe/workspace/NodeJs-            02/home/lixuehe/workspace/JavaScript-day02/js01-lunbo/lunbo.html