功能一：复制文件内容

const fs = require("fs")
const path = require("path")

const fileName1 = path.resolve(__dirname,'data.txt')
const fileName2 = path.resolve(__dirname,'data-bak.txt')

// fs.createReadStream()—**用于读取一个可读的文件流**
const readStream = fs.createReadStream(fileName1)

// fs.createWriteStream()—用于对文件流进行写入
const writeStream = fs.createWriteStream(fileName2)

// 管道读写操作 — **读取`data.txt`文件内容，并将内容写入到`data-bak.txt`文件中**
readStream.pipe(``writeStream``)

// 监听上面管道读写操作的传输
readStream.on('data',chunk=>{
console.log(chunk.toString())
})
// 监听数据流传输完成
readStream.on('end',()=>{
console.log('copy done')
})

功能二：通过http-server中的GET请求返回某一文件的内容

const http = require("http")
const fs = require("fs")
const path = require("path")
const fileName = path.resolve(__dirname,'data.txt')

const server = http.createServer((req,res)=>{
if(req.method === 'GET'){
const readStream = fs.createReadStream(fileName)
readStream.pipe(res)
}
})
server.listen(8080)