Node.js 中的流Stream模块简介及如何使用流进行数据处理

const fs = require('fs');
const http = require('http');
const url = 'https://developer.mozilla.org';
// 创建一个可读流来读取文件
const readableStream = fs.createReadStream('example.txt');
// 创建一个可写流来写入控制台
const writableStream = process.stdout;
// 将可读流通过管道传递给可写流
readableStream.pipe(writableStream);

const https = require('https');
const fs = require('fs');
// 创建一个写入流，用于将数据保存到本地文件
const fileStream = fs.createWriteStream('data.txt');
// 发起 HTTP 请求
https.get(url, (response) => {
  // 将 HTTP 响应的可读流通过管道传递给文件写入流
  response.pipe(fileStream);
  // 监听完成事件
  response.on('end', () => {
    console.log('文件下载完成！');
  });
});

const zlib = require('zlib');
const fs = require('fs');
// 创建一个可读流（压缩文件）
const gzipStream = fs.createReadStream('archive.gz');
// 创建一个解压流
const unzip = zlib.createGunzip();
// 创建一个可写流（解压后的文件）
const outStream = fs.createWriteStream('uncompressed.txt');
// 通过管道处理流
gzipStream.pipe(unzip).pipe(outStream);

const fs = require('fs');
const parse = require('csv-parse');
const parser = parse({ delimiter: ',' });
const readableStream = fs.createReadStream('large_dataset.csv');
readableStream.pipe(parser);
parser.on('data', (row) => {
  console.log(row); // 处理每一行数据
});
parser.on('end', () => {
  console.log('处理完成！');
});

const request = require('request');
const fs = require('fs');
request.get('https://api.example.com/video')
  .pipe(fs.createWriteStream('video.mp4'))
  .on('finish', () => {
    console.log('视频下载完成！');
  });

const pump = require('pump');
const fs = require('fs');
const http = require('http');
const server = http.createServer((req, res) => {
  const fileStream = fs.createReadStream('file.txt');
  pump(fileStream, res, (err) => {
    if (err) {
      console.error('流传输错误：', err);
    }
  });
});
server.listen(3000);

const readable = fs.createReadStream('non-existent-file.txt');
readable.on('error', (err) => {
  console.error('读取文件时出错：', err);
});

const stream = fs.createWriteStream('output.txt');
stream.on('finish', () => {
  stream.destroy(); // 释放资源
});

const readable = fs.createReadStream('file.txt', { highWaterMark: 1024 * 1024 }); // 1MB