【转】nodejs 'readline' 逐行读取、写入文件内容
运用readline逐行读取的两种实现
效果图如下:
左边1.log 为源文件
右边1.readline.log为复制后的文件
下边为命令行输出
实现方式一:
- var readline = require('readline');
- var fs = require('fs');
- var os = require('os');
- var fReadName = './1.log';
- var fWriteName = './1.readline.log';
- var fRead = fs.createReadStream(fReadName);
- var fWrite = fs.createWriteStream(fWriteName);
- var objReadline = readline.createInterface({
- input: fRead,
- // 这是另一种复制方式,这样on('line')里就不必再调用fWrite.write(line),当只是纯粹复制文件时推荐使用
- // 但文件末尾会多算一次index计数 sodino.com
- // output: fWrite,
- // terminal: true
- });
- var index = 1;
- objReadline.on('line', (line)=>{
- var tmp = 'line' + index.toString() + ':' + line;
- fWrite.write(tmp + os.EOL); // 下一行
- console.log(index, line);
- index ++;
- });
- objReadline.on('close', ()=>{
- console.log('readline close...');
- });
实现方式二:
- var readline = require('readline');
- var fs = require('fs');
- var os = require('os');
- var fReadName = './1.log';
- var fWriteName = './1.readline.log';
- var fRead = fs.createReadStream(fReadName);
- var fWrite = fs.createWriteStream(fWriteName);
- var enableWriteIndex = true;
- fRead.on('end', ()=>{
- console.log('end');
- enableWriteIndex = false;
- });
- var objReadline = readline.createInterface({
- input: fRead,
- output: fWrite,
- terminal: true
- });
- var index = 1;
- fWrite.write('line' + index.toString() +':');
- objReadline.on('line', (line)=>{
- console.log(index, line);
- if (enableWriteIndex) {
- // 由于readline::output是先写入后调用的on('line')事件,
- // 所以已经读取文件完毕时就不需要再写行号了... sodino.com
- index ++;
- var tmp = 'line' + index.toString() + ':';
- fWrite.write(tmp);
- }
- });
- objReadline.on('close', ()=>{
- console.log('readline close...');
- });