From 8f4ee922dcdf9348ced0c36c428893c73561cfb4 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E5=8F=B6=E7=8E=89=E9=9C=9E?= <2656731479@qq.com> Date: Thu, 3 Mar 2022 08:18:16 +0800 Subject: [PATCH] 03-02 --- ...07\344\273\266\350\257\273\345\206\231.js" | 112 ++++++++++++++++++ ...05\345\255\230\345\244\247\345\260\217.js" | 23 ++++ .../stream.txt" | 1 + 3 files changed, 136 insertions(+) create mode 100644 "\345\217\266\347\216\211\351\234\236/2022-03-02\346\265\201\346\226\207\344\273\266\347\232\204\350\257\273\345\206\231/00\346\265\201\346\226\207\344\273\266\350\257\273\345\206\231.js" create mode 100644 "\345\217\266\347\216\211\351\234\236/2022-03-02\346\265\201\346\226\207\344\273\266\347\232\204\350\257\273\345\206\231/01\346\265\201\346\226\207\344\273\266\350\257\273\345\217\226\350\256\241\347\256\227\345\206\205\345\255\230\345\244\247\345\260\217.js" create mode 100644 "\345\217\266\347\216\211\351\234\236/2022-03-02\346\265\201\346\226\207\344\273\266\347\232\204\350\257\273\345\206\231/stream.txt" diff --git "a/\345\217\266\347\216\211\351\234\236/2022-03-02\346\265\201\346\226\207\344\273\266\347\232\204\350\257\273\345\206\231/00\346\265\201\346\226\207\344\273\266\350\257\273\345\206\231.js" "b/\345\217\266\347\216\211\351\234\236/2022-03-02\346\265\201\346\226\207\344\273\266\347\232\204\350\257\273\345\206\231/00\346\265\201\346\226\207\344\273\266\350\257\273\345\206\231.js" new file mode 100644 index 0000000..2a5b705 --- /dev/null +++ "b/\345\217\266\347\216\211\351\234\236/2022-03-02\346\265\201\346\226\207\344\273\266\347\232\204\350\257\273\345\206\231/00\346\265\201\346\226\207\344\273\266\350\257\273\345\206\231.js" @@ -0,0 +1,112 @@ +/** + * 用流去读写文件 + * + */ +// let startAt = Date.now(); +let fs = require("fs"); +// for(let i=0;i<20000;i++){ +// //writeFileSync 内部封装了 fopen fwrite fend +// fs.writeFileSync('./big1.txt','今天学习流文件的读写,还不知道难不难\n',{flag:'a'}); +// } +// let endAt=Date.now();//34秒 + +// console.log(endAt-startAt); +// let fd=fs.openSync('./big2.txt','w'); +// for(let j=0;j<500000;j++){ +// let str='今天学习流文件的读写,还不知道难不难\n'; +// fs.writeSync(fd,Buffer.from(str)); +// } +// fs.closeSync(fd); +// let endAt2=Date.now(); +// console.log(endAt2-endAt);//403毫秒 + +//怎么证明.readfile 耗费的内存 +//如果说我运行前的内存 ------运行后的内存 + +let os = require("os"); +let startMem=os.freemem();//运行前空闲的内存 +// console.log(startMem); +// let fd=fs.openSync('./big2.txt','r'); +// let bf2= Buffer.alloc(25.2*1024*1024) +// fs.readSync(fd,bf2,0,25.2*1024*1024);//30m +fs.readFileSync('./big2.txt');//fopen fread fclose +let endMem=os.freemem();//打开后空闲的内存 +console.log((startMem-endMem)/1024/1024); +//fs.closeSync(fd); + +/** + * stream的读取 + * createReadStream(path: PathLike, options?: BufferEncoding | ReadStreamOptions) + * path 文件路径 + * option + * flags?: 标识 + encoding?: 编码 + 应用场景：读取大文件 + */ + +let readStram=fs.createReadStream('./stream.txt',{encoding:'utf-8'}); + +// stram on 绑定 data +readStram.on('data',function(chunk){ + console.log(chunk+'=================='); +}); + +setTimeout(() => { + readStram.close();//把流关闭 +}, 5); + +/** + * stram open 打开文件时触发事件 + */ +readStram.on('open',function(fd){ + console.log('文件描述符号'+fd); +}); +/** + * stram end 表示数据流完了 + */ +readStram.on('end',function(){ + console.log('i am end 数据流完了'); +}) +/** + * stram close 关闭流 + */ +readStram.on('close',function(){ + console.log('i am close '); +}); + +/** + * 文件流的写入 + * createWriteStream(path: PathLike, options?: BufferEncoding | StreamOptions) + * path 文件路劲 + * BufferEncoding 编码 + * 文件不存在自动创建 + * + */ +let writeStream=fs.createWriteStream('./stream/write2.txt','utf-8'); +//write 流入数据 参数 chunk string 或者是 buffer 可循环写入 +let bf2='失恋一次不可怕，可以再来一次\n'; +writeStream.write(Buffer.from(bf2)); +writeStream.write(Buffer.from(bf2)); +writeStream.write(Buffer.from(bf2)); +writeStream.write(Buffer.from(bf2)); +writeStream.write(Buffer.from(bf2)); +writeStream.write(Buffer.from(bf2)); +writeStream.close(); + +/** + * pipe 中文管道 + * +*/ + +let readStram2 = fs.createReadStream('./stream/write2.txt',{encoding:'utf-8'}); +let writeStream2= fs.createWriteStream('./stream/write3.txt'); +/** + * pipe 接入水管后,绑定数据流 + */ +readStram2.pipe(writeStream2); + +/** + * 作业 + * 创建一个大文件，然后去计算一下流方式读取的内存消耗 + * + */ \ No newline at end of file diff --git "a/\345\217\266\347\216\211\351\234\236/2022-03-02\346\265\201\346\226\207\344\273\266\347\232\204\350\257\273\345\206\231/01\346\265\201\346\226\207\344\273\266\350\257\273\345\217\226\350\256\241\347\256\227\345\206\205\345\255\230\345\244\247\345\260\217.js" "b/\345\217\266\347\216\211\351\234\236/2022-03-02\346\265\201\346\226\207\344\273\266\347\232\204\350\257\273\345\206\231/01\346\265\201\346\226\207\344\273\266\350\257\273\345\217\226\350\256\241\347\256\227\345\206\205\345\255\230\345\244\247\345\260\217.js" new file mode 100644 index 0000000..a3024f8 --- /dev/null +++ "b/\345\217\266\347\216\211\351\234\236/2022-03-02\346\265\201\346\226\207\344\273\266\347\232\204\350\257\273\345\206\231/01\346\265\201\346\226\207\344\273\266\350\257\273\345\217\226\350\256\241\347\256\227\345\206\205\345\255\230\345\244\247\345\260\217.js" @@ -0,0 +1,23 @@ +// 创建一个大文件，然后去计算一下流方式读取的内存消耗 + + +// 引入模块 +let fs = require('fs') +let os = require("os"); +//文件流的写入 +let writeStream = fs.createWriteStream('./stream.txt', 'utf-8'); +for (let j = 0; j < 50; j++) { + let str = 'sfdsfsfsfs'; + writeStream.write(Buffer.from(str)); + } + + let startMem=os.freemem();//运行前 + + console.log(startMem); + // 文件流的读取 + let readStream=fs.createReadStream('./stream.txt','utf-8'); + readStream.on('data',function(string){ console.log(string); }) + readStream.on('end',function(){ console.log('关闭'); }); + //打开后空闲的内存 + let endMem=os.freemem(); + console.log((startMem-endMem)/1024/1024); \ No newline at end of file diff --git "a/\345\217\266\347\216\211\351\234\236/2022-03-02\346\265\201\346\226\207\344\273\266\347\232\204\350\257\273\345\206\231/stream.txt" "b/\345\217\266\347\216\211\351\234\236/2022-03-02\346\265\201\346\226\207\344\273\266\347\232\204\350\257\273\345\206\231/stream.txt" new file mode 100644 index 0000000..0735bd8 --- /dev/null +++ "b/\345\217\266\347\216\211\351\234\236/2022-03-02\346\265\201\346\226\207\344\273\266\347\232\204\350\257\273\345\206\231/stream.txt" @@ -0,0 +1 @@ +sfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfssfdsfsfsfs \ No newline at end of file -- Gitee