nodejs 文本逐行读写功能的实现

Posted 2021-01-27 zhcgis

利用nodejs实现：逐行读写（从一个文件逐行复制到另外一个文件）；逐行读取、处理和写入（读取一行，处理后，写入另一个文件）

1.所需要的模块： fs，os，readline

2.具体实现：

　a. 功能的实现：readWriteFileByLine.js

var fs = require(‘fs-extra‘);
var os = require(‘os‘);
var rl =  require(‘readline‘);

/**
 * 按行读写，无读取内容的处理，类似单纯的复制功能
 * @param {string} readName 
 * @param {string} writeName 
 */
var readWriteFileByLine = function(readName, writeName){
    var readStream =  fs.createReadStream(readName);
    var writeStream = fs.createWriteStream(writeName);
    var readLine = rl.createInterface({
        input: readStream,
        output: writeStream,
        terminal: true
    })
}

/**
 * 按行读写，中间包涵对读取的行内容的处理
 * @param {string} readName 
 * @param {string} writeName 
 * @param {Function} callback 
 */
var readWriteFileByLineWithProcess = function(readName,writeName,callback){
    var readStream = fs.createReadStream(readName);
    var writeStream = fs.createWriteStream(writeName);
    var readLine = rl.createInterface({
        input: readStream
    })
    readLine.on(‘line‘,function(line){
        var rs = callback(line);
        writeStream.write(rs + os.EOL);
    })
}

exports.readWriteFileByLine = readWriteFileByLine;
exports.readWriteFileByLineWithProcess = readWriteFileByLineWithProcess

　　b. 功能的调用：index.js

var rwByLine = require(‘./lib/readWriteFileByLine.js‘)

//按行读写，对行做字符替换处理
var readName = ‘./obj.txt‘;
var writeName = ‘./rt.txt‘;
rwByLine.readWriteFileByLineWithProcess(readName,writeName,function(line){
    var rs = line.toString().replace("\",‘/‘);
    return rs;
})

//按行读写，无处理
readName = ‘./obj.txt‘;
writeName = ‘./rt1.txt‘;
rwByLine.readWriteFileByLine(readName,writeName);