'use strict'
var url = require('url');
var path = require('path');
var fs = require('fs');
var http = require('http');
//get the current path
//var root = path.resolve('.');//以当前的目录为服务器的根目录
var root = path.resolve(process.argv[2] || '.');//以输入的参数作为服务器的根目录，如果没有输入参数就将当前目录作为服务器根目录
console.log('local root dir :' + root);
//create server
var server = http.createServer(function(request, response) {
  //get the path of URL
  var pathname = url.parse(request.url).pathname;
  //get the local path
  var filepath = path.join(root, pathname);
  //get the file stat and output the request file by callback function
  fs.stat(filepath, function(err, stat) {
    if(!err && stat.isFile()) {
      console.log('200' + request.url);
      response.writeHead(200);
      fs.createReadStream(filepath).pipe(response);//没有必要手动读取文件内容。由于response对象本身是一个Writable Stream，直接用pipe()方法就实现了自动读取文件内容并输出到HTTP响应。
    } else {
      console.log('404' + request.url);
      response.writeHead(404);
      response.end('404 Not Found');
    }
  });
});
server.listen(8080);
console.log('Server is running at http://127.0.0.1:8080/');

path.resolve() 路径寻航（这名字不错）
path.resolve([from…], to)

path.resolve('foo/bar', '/tmp/file/', '..', 'a/../subfile')
//相当于：
cd foo/bar
cd /tmp/file/
cd ..
cd a/../subfile1
path.join([path1],path[2]...) 路径合并

path.join('///foo', 'bar', '//baz/asdf', 'quux', '..');
=>'/foo/bar/baz/asdf'

path.normalize('/foo/bar//baz/asdf/quux/..');
=> '/foo/bar/baz/asdf'

response.end([data], [encoding])