node 壓縮模塊速成

1. 壓縮與解壓縮處理

可使用zlib模塊進行壓縮及解壓縮處理,壓縮文件之後能夠減小體積，加快傳輸速度和節約帶寬 代碼

2. 壓縮對象

壓縮和解壓縮對象都是一個可讀可寫流

方法	說明
zlib.createGzip	返回Gzip流對象，使用Gzip算法對數據進行壓縮處理
zlib.createGunzip	返回Gzip流對象，使用Gzip算法對壓縮的數據進行解壓縮處理
zlib.createDeflate	返回Deflate流對象，使用Deflate算法對數據進行壓縮處理
zlib.createInflate	返回Deflate流對象，使用Deflate算法對數據進行解壓縮處理

3. 壓縮和解壓縮

var zlib = require('zlib');
var fs = require('fs');

function zip(src) {
    var gzip = zlib.createGzip();//建立壓縮流
    var inputStream = fs.createReadStream(src);
    var outputStream = fs.createWriteStream(src+'.gz');
    inputStream.pipe(gzip).pipe(outputStream);
}
zip('source.txt');

function unzip(src){
    var gunzip = zlib.createGunzip();
    var inputStream = fs.createReadStream(src);
    var outputStream = fs.createWriteStream(src.slice(0,-3));
    inputStream.pipe(gunzip).pipe(outputStream);
}

unzip('source.txt.gz');

複製代碼

4. 在http中的應用

var zlib = require('zlib');
var fs = require('fs');
var http = require('http');
http.createServer(function (request, response) {
    var raw = fs.createReadStream('.' + request.url);
    var acceptEncoding = request.headers['accept-encoding'];
    if (!acceptEncoding) {
        acceptEncoding = '';
    }
    if (acceptEncoding.match(/\bdeflate\b/)) {
        response.setHeader('Content-Encoding','deflate');
        raw.pipe(zlib.createDeflate()).pipe(response);
    } else if (acceptEncoding.match(/\bgzip\b/)) {
        response.setHeader('Content-Encoding','gzip');
        raw.pipe(zlib.createGzip()).pipe(response);
    } else {
        raw.pipe(response);
    }
}).listen(9090)
複製代碼

var zlib = require('zlib');
var fs = require('fs');
var http = require('http');

var request = http.get({
    host: 'localhost',
    path: '/index.html',
    port: 9090,
    headers: {
        'accept-encoding': 'gzip,deflate'
    }
})

request.on('response', function (response) {
    var output = fs.createWriteStream('test.txt');
    switch (response.headers['content-encoding']) {
        case 'gzip':
            response.pipe(zlib.createGunzip()).pipe(output);
            break;
        case 'deflate':
            response.pipe(zlib.createInflate()).pipe(output);
            break;
        default:
            response.pipe(output);
            break;
    }
});
request.end();
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5. 方法調用

var zlib = require('zlib');
var fs = require('fs');

var out = fs.createWriteStream('input.log');
var input = 'input';
zlib.gzip(input, function (err, buffer) {
    if (!err) {
        zlib.unzip(buffer, function (err, buffer) {
            if (!err) {
                console.log(buffer.toString());
                out.end(buffer);
            }
        })
    }
})複製代碼