Node.js中文件系统fs模块的使用及常用接口

const fs = require('fs')
fs.stat('hello.js', (error,stats)=>{
 if(error) {
 console.log(error)
 } else {
 console.log(stats)
 console.log(`文件：${stats.isFile()}`)
 console.log(`目录：${stats.isDirectory()}`)
 }
})

const fs = require('fs')
fs.mkdir('logs', error => {
 if(error) {
 console.log(error)
 } else {
 console.log('目录创建成功！')
 }
})

const fs = require('fs')
fs.rmdir('logs', error => {
 if(error) {
 console.log(error)
 } else {
 console.log('成功删除了目录 logs')
 }
})

const fs = require('fs')
fs.writeFile('logs/hello.log','您好~\n', error => {
 if(error) {
 console.log(error)
 } else {
 console.log('成功写入文件');
 }
})

const fs = require('fs')
fs.appendFile('logs/hello.log','hello~\n', error => {
 if(error) {
 console.log(error)
 } else {
 console.log('成功写入文件');
 }
})

const fs = require('fs')
fs.readFile('logs/hello.log','utf-8', (error, data) => {
 if(error) {
 console.log(error)
 } else {
 console.log(data);
 }
})

const fs = require('fs')
fs.unlink(`logs/${file}`, error => {
 if(error) {
 console.log(error)
 } else {
 console.log(`成功删除了文件： ${file}`)
 }
})

const fs = require('fs')
fs.readdir('logs', (error, files) => {
 if(error) {
 console.log(error)
 } else {
 console.log(files);
 }
})

const fs = require('fs')
fs.rename('js/hello.log', 'js/greeting.log', error => {
 if(error) {
 console.log(error)
 } else {
 console.log('重命名成功')
 }
})

const mkdirp = require('mkdirp')
mkdirp('tmp/foo/bar/baz').then(made => console.log(`创建目录于： ${made}`))
// 创建目录于： /Users/zhangbing/github/CodeTest/Node/fs/tmp

const fs = require('fs')

const path = './upload'
fs.stat(path, (err, data) => {
 if(err) {
 // 执行创建目录
 mkdir(path)
 return
 }
 if(data.isDirectory()) {
 console.log('upload目录存在');
 }else{
 // 首先删除文件，再去执行创建目录
 fs.unlink(path, err => {
  if(!err) {
  mkdir(path)
  }
 })
 }
})

function mkdir(dir) {
 fs.mkdir(dir, err => {
 if(err) {
  console.log(err);
  return
 }
 })
}

const fs = require('fs')
const path = './wwwroot'
const dirArr = []

const dirs = fs.readdirSync(path)
dirs.forEach(item => {
 if(fs.statSync(path + '/' + item).isDirectory()) {
 dirArr.push(item)
 }
})
console.log('dirArr', dirArr)
// dirArr [ 'css', 'images', 'js' ]

const fs = require('fs')
const path = './wwwroot'
const dirArr = []

function isDir(path) {
 return new Promise((resolve, reject) => {
 fs.stat(path, (error, stats) => {
  if(error) {
  console.log(error)
  reject(error)
  return
  }
  if(stats.isDirectory()) {
  resolve(true)
  } else {
  resolve(false)
  }
 })
 })
}

function main(){
 fs.readdir(path, async (error, data) => {
 if(error) {
  console.log(error)
  return
 } else {
  for(let i = 0; i < data.length; i++) {
  if(await isDir(path + '/' + data[i])) {
   dirArr.push(data[i])
  }
  }
  console.log('dirArr', dirArr)
 }
 })
}

main() // dirArr [ 'css', 'images', 'js' ]

const fs = require("fs")
//创建一个可读流
const readerStream = fs.createReadStream('input.txt')
//创建一个可写流
const writerStream = fs.createWriteStream('output.txt')
//管道读写操作
//读取input.txt文件内容，并将内容写入到output.txt文件中
readerStream.pipe(writerStream)
console.log("程序执行完毕")
fs.createReadStream 从文件流中读取数据
const fs = require('fs')
const fileReadStream = fs.fileReadStream('demo1.js')
let count = 0
let str = ''
fileReadStream.on('data', chunk => {
 console.log(`${++count}接收到：${chunk.length}`)
 str += chunk
})
fileReadStream.on('end', () => {
 console.log('---结束---')
 console.log(count + '，' + star)
})
fileReadStream.on('error', error => {
 console.log(error)
})
fs.createWriteStream 写入文件
const fs = require("fs")
const data ='我是从数据库获取的数据，我要保存起来'
//创建一个可以写入的流，写入到文件output.txt中
const writerStream = fs.createWriteStream('output.txt')
//使用utf8编码写入数据
writerStream.write(data,'UTF8')
//标记文件末尾
writerStream.end()
//处理流事件-->finish事件
writerStream.on('finish', () => {
 /*finish-所有数据已被写入到底层系统时触发。*/
 console.log("写入完成。")
})
writerStream.on('error', err => {
 console.log(err.stack);
})
console.log("程序执行完毕")

const fs = require("fs")

const readStream = fs.createReadStream('./2020.png')
const writeStream = fs.createWriteStream('./wwwroot/images/2021.png')

readStream.pipe(writeStream)