第五章、nodejs高级

目录

• 十六、知识点补充
  • 22、gzip
  • 23、crypto
  • 24、uncaughtException
  • 25、detached
  • 26、fork
  • 27、exec
  • 28、execFile

十六、知识点补充

22、gzip

const fs = require('fs')
const path = require('path')
const zlib = require('zlib')

/*
* Accept-Encoding: gzip：浏览器告诉服务器所支持的编码
* Content-Encoding: gzip：服务器告诉浏览器所提供的编码
*/

const gzip = (src) => {
  fs.createReadStream(src)
    .pipe(zlib.createGzip())
    .pipe(fs.createWriteStream(src + '.gz'))
}
// gzip(path.join(__dirname, 'abc.txt'))

const gunzip = (src) => {
  fs.createReadStream(src)
    .pipe(zlib.createGunzip())
    .pipe(fs.createWriteStream(path.join(__dirname, path.basename(src, '.gz'))))
}
gunzip(path.join(__dirname, 'abc.txt.gz'))

23、crypto

/**
 * 1、可以用来校验要下载的文件是否被改动过
 * 2、对密码进行加密
 */
const crypto = require('crypto')
// console.log(crypto.getHashes())
// const hash = crypto.createHash('sha1')
// openssl genrsa -out rsa_private.key 1024：命令生成密钥
const hash = crypto.createHmac('sha1', 'linlong')
hash.update('hello')
hash.update('world')
// sha1：40位
// md5：32位
// hex：十六进制
console.log(hash.digest('hex'))

const crypto = require('crypto')
const data = 'hello world'
const password = 'linlong'

const cipher = crypto.createCipher('aes-256-cbc', password);
cipher.update(data, 'utf8')
const result = cipher.final('hex');
console.log(result)

const decipher = crypto.createDecipher('aes-256-cbc', password);
decipher.update(result, 'hex')
const r = decipher.final('utf8');
console.log(r)

24、uncaughtException

// 专门用来处理未捕获的异常（容易引起内存泄露，不常用）
process.on('uncaughtException', (error) => {
  console.log(error)
})
setTimeout(() => {
  console.log('程序')
}, 3000)
throw new Error('异常')

25、detached

const childProcess = require("child_process")
const fs = require('fs')
const path = require('path')

const fd = fs.openSync(path.join(__dirname, 'msg.txt'), 'w', 0o666)
const p1 = childProcess.spawn('node', ['test.js'], {
  stdio: ['ignore', fd, 'ignore'],
  cwd: path.join(__dirname),
  detached: true
})
// 默认情况下父进程会等待所有的子进程退出后才可以退出
// detached配置、unref方法，可以让父进程不用等待而直接退出
p1.unref()

let i = 0
const timer = setInterval(() => {
  process.stdout.write(new Date().toUTCString() + '\r\n')
  if (i++ >= 10) {
    clearInterval(timer)
  }
}, 1000)

26、fork

// fork exec execFile 它们其实都是基于spawn的改进方法
const {fork, spawn} = require('child_process')
/*
function fork(modulepath, args, options) {
  const {silent} = options
  const opts = Object.assign({}, options)
  if (silent) {
    opts.stdio = ['ignore', 'ignore', 'ignore']
  } else {
    opts.stdio = [process.stdin, process.stdout, process.stderr]
  }
  spawn('node', [modulepath, ...args], opts)
}
*/
const child = fork('test.js', ['zfpx'], {
  cwd: __dirname,
  silent: false
})
child.on('message', function (data) {
  console.log(data)
})
child.send({name: 'zfpx'})

process.stdout.write('world' + process.argv[2])
process.on('message', function (msg) {
  process.send('子进程：' + JSON.stringify(msg))
})

27、exec

const {exec} = require('child_process')
const path = require('path')
const p1 = exec('node test.js a b c', {
  cwd: path.resolve(__dirname),
  encoding: 'utf8',
  // timeout: 10,
  maxBuffer: 1024 * 1024
}, function (error, stdout, stderr) {
  console.log(error)
  console.log(stdout)
})

for (let i = 2; i < process.argv.length; i++) {
  process.stdout.write(process.argv[i] + '\r\n')
}

28、execFile

const {execFile} = require('child_process')
const path = require('path')
const p1 = execFile('node', ['test.js', 'a', 'b', 'c'], {
  cwd: path.resolve(__dirname),
  encoding: 'utf8',
  // timeout: 10,
  maxBuffer: 1024 * 1024
}, function (error, stdout, stderr) {
  console.log(error)
  console.log(stdout)
})

for (let i = 2; i < process.argv.length; i++) {
  process.stdout.write(process.argv[i] + '\r\n')
}