nodejs随记03

2023-01-07 08:10:52

文件操作

文件系统的操作

* fs.readFile(filename, [options], callback)

* fs.writeFile(filename, data, [options], callback)

//同步

  fs.writeFileSync('data/' + dist, fs.readFileSync(src));

//异步

  fs.readFile(src, function (err, data) {

    if (err) {

      throw err;

    } else {

      fs.writeFile(dist, data, function (err) {

        if (err) throw err;

      })

    }

  });

数据流操作
- fs.createReadStream(path, [options]),
- fs.createWriteStream(path, [options])

//使用pipe

  fs.createReadStream(src).pipe(fs.createWriteStream('./data/' + dist));

//

  var rs = fs.createReadStream(src);

  var ws = fs.createWriteStream(dist);

  rs.on('data', function (chunk) {

    if (ws.write(chunk) === false) {

      //判断写入还是缓存

      rs.pause();

    }

  });

  rs.on('end', function () {

    ws.end();

  });

  ws.on('drain', function () {

  	//已经写入的话继续

    rs.resume();

  });

fs内置模块常用api

文件属性读写

* fs.stat //获取文件信息

* fs.chown //更改文件所有权

* fs.chmod //改写文件的读写权限
文件内容读写

* fs.readFile

* fs.readdir

* fs,writeFile

* fs.mkdir
底层文件操作

* fs.open

* fs.read

* fs.close

* fs.unlink

读取文件

使用fs.readStream读取文件；

var http = require('http');

var path = require('path');

var fs = require('fs');

var url = require('url');

var mimeTypes = {

  '.js' : 'text/javascript',

  '.html': 'text/html',

  '.css' : 'text/css'

};

//设置白名单

var whitelist = [

  '/index.html',

  '/style.css',

  '/script.js'

];

var cache = {

  store: {},

  maxSize : 26214400, //(bytes) 25mb

  maxAge: 5400 * 1000, //(ms) 1 and a half hours

  clearnAfter: 7200 * 1000,//(ms) two hours

  cleanedAt: 0, //to be set dynamically

  clean: function (now) {

    if (now - this.cleanAfter > this.cleanedAt) {

      this.cleanedAt = now;

      var maxAge = this.maxAge;

      Object.keys(this.store).forEach(function (file) {

        if (now > this.store[file].timestamp + maxAge) {

          delete this.store[file];

        }

      }.bind(this));

    }

  }

};

http.createServer(function (req, res) {

  if (req.url === '/favicon.ico') return;

  var lookup = url.parse(decodeURI(req.url)).pathname;

  lookup = path.normalize(lookup);

  lookup = (lookup === '/') ? '/index.html' : lookup;

  if (whitelist.indexOf(lookup) === -1) {

    res.writeHead(404);

    return res.end('Page Not Found!');

  }

  var f = './public' + lookup;

  console.log(f);

  fs.exists(f, function (exists) {

    if (exists) {

      var headers = {'Content-Type': mimeTypes[path.extname(lookup)]};

      if(cache.store[f]) {

        res.writeHead(200, headers);

        return res.end(cache.store[f].content);

      }

      var s = fs.createReadStream(f).once('open', function () {

        res.writeHead(200, headers);

        this.pipe(res);

      }).once('err', function (err) {

        console.log('err:', e);

        res.writeHead(500);

        return res.end('Server Error!');

      });

      //对输出流保存cache处理;设置buffer需要大小,使用fs.stat获取

      return fs.stat(f, function (err, stats) {

        if (stats.size < cache.maxSize) {

          var bufferOffset = 0;

          cache.store[f] = {content: new Buffer(stats.size), timestamp: Date.now()};

          s.on('data', function (chunk) {

            chunk.copy(cache.store[f].content, bufferOffset);

            bufferOffset += chunk.length; //大小设置

          })

        }

      });

    }

    res.writeHead(404);

    return res.end('Not find Source!');

  });

  //清除超出时间的缓存

  cache.clean(Date.now());

}).listen(3000);

使用fs.readFile读取文件

var http = require('http');

var path = require('path');

var fs = require('fs');

var mimeTypes = {

  '.js' : 'text/javascript',

  '.html': 'text/html',

  '.css' : 'text/css'

};

var cache = {};

function cacheAndDeliver (f, cb) {

  fs.stat(f, function (err, stats) {

    if (err) return console.log('Error: ',err);

    var lastChanged = Date.parse(stats.ctime);

    var isUpdated = cache[f] && lastChanged > cache[f].timestamp;

    if (!cache[f] || isUpdated) {

      fs.readFile(f, function (err, data) {

        if (!err) cache[f] = {content: data, timestamp: Date.now()}; //store a Unix time stamp

        cb(err, data);

      });

      return;

    }

    console.log('loading ' + f + ' from cache');

    return cb(null, cache[f].content);

  })

};

http.createServer(function (req, res) {

  if (req.url === '/favicon.ico') return;

  var lookup = path.basename(decodeURI(req.url)) || 'index.html';

  var f = './public/' + lookup;

  fs.exists(f, function (exists) {

    if (exists) {

      cacheAndDeliver(f, function (err, data) {

        if (err) {

          res.writeHead(500);

          res.end('Server Error!');

          return;

        }

        var headers = {'Content-Type': mimeTypes[path.extname(lookup)]};

        res.writeHead(200, headers);

        res.end(data);

      });

      return; //注意return的位置

    }

    res.writeHead(404);

    return res.end('Not find Source!');

  })

}).listen(3000);

路径处理

url路径处理:

* url.parse(req.url).pathname; url.parse(req.url, true).query
文件路径处理:

* path.join(__dirname, pathname);

path.dirname('/foo/bar/baz/asdf/quux')      '/foo/bar/baz/asdf'

//

path.basename('/foo/bar/baz/asdf/quux.html')    'quux.html'

path.basename('/foo/bar/baz/asdf/quux.html', '.html')     'quux'

//

path.extname('index.coffee.md')      '.md'

path.extname('index.')            '.'

path.extname('index')             ''

path.extname('.index')             ''

递归一个文件夹例子

function travelS(dir, cb) {

  fs.readdirSync(dir).forEach(function (file) {

    var pathname = path.join(dir, file);

    if (fs.statSync(pathname).isDirectory()) {

      travelS (pathname, callback);

    } else {

      callback(pathname);

    }

  })

};

process

`事件`

process.on('exit', function(){});
process.on('uncaughtException', function(){});
信号事件: :SIGINT,SIGUSR1...
- 一个简单的方式发送SIGINT信号的方法是:control-c

`方法`

process.uptime(): Node的运行时间;
process.nextTick(func): 将函数放到后面运行;
process.cwd(): 显示当前文件夹目录；
process.exit(code): 退出进程，内部调用进程的exit事件,code：0表示成功退出，1表示失败退出;
process.kill(pid[, signal])#: 退出进程, 触发第二参数，为SIGINT,SIGHUP

`属性`

process.env: 运行环境参数;
process.stdin: 输入流;
- process.stdin.resume();: 开启输入流,调用一次后程序不会马上停止;
- process.stdin.setEncoding('utf8')
process.stdout: 输出流;

process.stdin.resume();

process.stdin.pipe(process.stdout);

process.stderr: 错误流；
process.pid: 进程的pid

数据交互

上传数据常用类型

application/x-www-form-urlencoded;
application/json;
application/xml;
multipart/form-data;

JSONP

//client

 var who = 'ryan';

  function cb(o) {

    alert(o.name + ' : ' + o.description);

  }

  var s = document.createElement('script');

  s.src = 'http://localhost:3000/?callback=cb&who=' + who;

  document.getElementsByTagName("head")[0].appendChild(s);

//server

  var profiles = require("./profiles.json");

  .....

  if(cb && who) {

    profile = cb + '(' + JSON.stringify(profiles[who]) + ')';

    return res.end(profile);

  }

上传文件例子

var http = require('http');

var formiable = require('formidable');

var fs = require('fs');

var form = require('fs').readFileSync('./public/form-upload.html');

http.createServer(function (req, res) {

  if (req.method === 'GET') {

    res.writeHead(200, {'Content-Type': 'text/html'});;

    return res.end(form);

  }

  if (req.method === 'POST') {

    var incoming = new formiable.IncomingForm();

    var f = './uploads';

    incoming.uploadDir = f;

    form.multiples = true;

    !fs.existsSync(f) && fs.mkdir(process.env.PWD + '/uploads'); //使用绝对路径创建文件夹

    incoming.on('fileBegin', function (field, file) {

      if(file.name) file.path += "-" + file.name;

    }).on('file', function (field, file) {

      if (file.size == 0) return fs.unlinkSync(file.path);

      res.write(file.name + ' received\n');

    }).on('field', function (field, value) {

      res.write(field + ' : ' + value + '\n');

    }).on('end', function () {

      res.end('All files received!');

    }).parse(req, function (err, fields, files) {

    });

  }

  if(req.method === 'PUT') {

    var f = './uploads';

    !fs.existsSync(f) && fs.mkdir(f);

    var fileData = new Buffer(+req.headers['content-length']);

    var bufferOffset = 0;

    req.on('data', function (chunk) {

      chunk.copy(fileData, bufferOffset); //连接Buffer对象的正确方法

      bufferOffset += chunk.length;

    }).on('end', function () {

      var rand = (Math.random()*Math.random()).toString(16).replace('.','');

      var to = 'uploads/' + rand + "-" + req.headers['x-uploadedfilename'];

      fs.writeFile(to, fileData, function (err) {

        if (err) throw err;

        console.log('Saved file to ' + to);

      })

    })

  }

}).listen(3000);

码农公寓

文件操作

fs内置模块常用api

读取文件

路径处理

process

事件

方法

属性

数据交互

上传数据常用类型

JSONP

上传文件例子

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`事件`

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`属性`