Transform 流举例

内置的Transform Stream

const fs = require('fs')
const zlib = require('zlib')
const file = process.argv[2]

fs.createReadStream(file)  // 读取文件
    .pipe(zlib.createGzip()) // 创建一个压缩流
    .pipe(fs.createWriteStream(file + ".gz"));  // 创建一个文件流

创建一个进度条pipe和加密

const fs = require("fs");
const zlib = require("zlib");
const file = process.argv[2];
const crypto = require("crypto");


const { Transform } = require("stream");

const reportProgress = new Transform({
    transform(chunk, encoding, callback) {
        process.stdout.write(".");
        callback(null, chunk);
    }
});


fs.createReadStream(file)
    .pipe(crypto.createCipher("aes192", "123456"))
    .pipe(zlib.createGzip())
    .pipe(reportProgress)
    .pipe(fs.createWriteStream(file + ".gz"))
    .on("finish", () => console.log("Done"));

image.png

node.js stream文档
英文链接
中文链接

面试题