Nodejs關於gzip/deflate壓縮

http://homeway.me

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0x01.關於

寫http時候，在接收http請求時候，出現亂碼，後來發現是gzip沒有解壓。

關於gzip/deflate壓縮，有放入管道壓縮，和非管道壓縮方法。

0x02.非管道壓縮

代碼以下：

#! /usr/local/bin/node

var http = require('http'),
    querystring = require('querystring'),
    zlib = require('zlib');
var args = {
    //參數以及備用數據
    contents : querystring.stringify({  
        //發包的信息
        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要轉成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);
});

0x02.管道壓縮

Node中的I/O是異步的，所以對磁盤和網絡的讀寫須要經過回調函數來讀取數據。

當內存中沒法一次裝下須要處理的數據時，或者一邊讀取一邊處理更加高效時，咱們就須要用到數據流。

NodeJS中經過各類Stream來提供對數據流的操做。

官網提供了管道方法：

// 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;
    }
});

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本文出自 夏日小草,轉載請註明出處： http://homeway.me/2015/03/03/nodejs-gzip-deflate-compression

by 小草

2015-03-03 14:17:20