压缩在node.js中使用zlib的字典数据的

Question

如果我要放气串s我可以做

var d = zlib.deflateSync(s); 

我注意到在documentation under Class Options，我可以集字典，但我不知道该怎么用它。

如何用字典压缩字符串？

Answer 1

对于Nodejs中的用法，您需要传递类Buffer的实例作为要与zlib进行比较的数据字典。

https://github.com/nodejs/node/blob/master/lib/zlib.js#L347

if (opts.dictionary) { 
    if (!(opts.dictionary instanceof Buffer)) { 
     throw new Error('Invalid dictionary: it should be a Buffer instance'); 
    } 
    } 

请参考下面这个例子： How to find a good/optimal dictionary for zlib 'setDictionary' when processing a given set of data?

根据这一点，你可以做到以下几点：

var zlib = require('zlib'); 
var result = zlib.deflateSync('The dictionary should consist of strings (byte sequences) that are likely to be encountered later in the data to be  compressed, with the most commonly used strings preferably put towards the end of the dictionary. Using a dictionary is most useful when the data to be compressed is short and can be predicted with good accuracy; the data can then be compressed better than with the default empty dictionary.',  {'dictionary': new Buffer('rdsusedusefulwhencanismostofstringscompresseddatatowithdictionarybethe', 'utf8') }); 
console.log(result);