在Node.js中用zlib实现带字典的数据压缩

Question

var d = zlib.deflateSync(s);

我在Class Options下的文档中注意到我可以设置dictionary，但我不知道如何使用它。

如何用字典缩放字符串？

Answer 1

对于Nodejs中的用法，您需要传递一个类Buffer实例作为您希望zlib与之比较的数据字典。

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');
    }
  }

请参考这个例子：当处理给定的数据集时，如何为zlib的“集合字典”找到一个好的/最优的字典？

 var zlib = require('zlib');
 var input = '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.';
 var dictionary = Buffer.from('rdsusedusefulwhencanismostofstringscompresseddatatowithdictionarybethe', 'utf8');
 var result = zlib.deflateSync(input, {dictionary: dictionary});
 console.log(result);