Nodejs关于gzip/deflate压缩详解

0x01.关于

写http时候,在接收http请求时候,出现乱码,后来发现是gzip没有解压。

关于gzip/deflate压缩,有放入管道压缩,和非管道压缩方法。

0x02.管道压缩

Node中的I/O是异步的,因此对磁盘和网络的读写需要通过回调函数来读取数据。

当内存中无法一次装下需要处理的数据时,或者一边读取一边处理更加高效时,我们就需要用到数据流。

NodeJS中通过各种Stream来提供对数据流的操作。

官网提供了管道方法:


// client request example

var zlib = require('zlib');

var http = require('http');

var fs = require('fs');

var request = http.get({ host: 'homeway.me',

                     path: '/',

                     port: 80,

                     headers: { 'accept-encoding': 'gzip,deflate' } });

request.on('response', function(response) {

    var output = fs.createWriteStream('izs.me_index.html');

    switch (response.headers['content-encoding']) {

        // or, just use zlib.createUnzip() to handle both cases

        case 'gzip':

            response.pipe(zlib.createGunzip()).pipe(output);

            break;

        case 'deflate':

            response.pipe(zlib.createInflate()).pipe(output);

            break;

        default:

            response.pipe(output);

            break;

    }

});

0x03.非管道压缩

代码如下:


#! /usr/local/bin/node

var http = require('http'),

    querystring = require('querystring'),

    zlib = require('zlib');

var args = {

    //参数以及备用数据

    contents : querystring.stringify({  

        //发包的信息

        name:'homeway.me',

    }), 

};

var options = {

    hostname: 'homeway.me',

    port: 80,

    path: '/',

    method: 'GET',

    headers: {

        'Accept':'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',

        'Content-Length': args.contents.length,

        'User-Agent':'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/42.0.2311.11 Safari/537.36',

        'Accept-Encoding':'gzip, deflate',

   },

};

var get = function ( options, args, callback ){

    var req = http.request(options, function (res) {

        var chunks =[], data, encoding = res.headers['content-encoding'];

        // 非gzip/deflate要转成utf-8格式

        if( encoding === 'undefined'){

            res.setEncoding('utf-8'); 

        }

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

            chunks.push(chunk);

        }); 

        res.on('end', function (){

            var buffer = Buffer.concat(chunks);

            if (encoding == 'gzip') {

                zlib.gunzip(buffer, function (err, decoded) {

                    data = decoded.toString();

                    callback( err, args, res.headers, data); 

                });

            } else if (encoding == 'deflate') {

                zlib.inflate(buffer, function (err, decoded) {

                    data = decoded.toString();

                    callback( err, args, res.headers, data); 

                });

            } else {

                data = buffer.toString();

                callback( null, args, res.headers, data);

            } 

        });

    });

    req.write( args.contents ); 

    req.end();

};

get( options, args, function (err, args, headers, data){

    console.log('==>header \n', headers);

    console.log('==data \n', data);

});

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