Node.js文件操作方法汇总

Node.js和其他语言一样,也有文件操作。先不说node.js中的文件操作,其他语言的文件操作一般也都是有打开、关闭、读、写、文件信息、新建删除目录、删除文件、检测文件路径等。在node.js中也是一样,也都是这些功能,可能就是api与其他语言不太一样。
一、同步、异步打开关闭

/** * Created by Administrator on 2016/3/21. */var fs=require（"fs"）;//同步读 fs.openSync = function（path, flags, mode）//模块fs.js文件中如上面定义的openSync 函数3个参数//.1.path 文件路径//2.flags 打开文件的模式//3.model 设置文件访问模式//fd文件描述var fd=fs.openSync（"data/openClose.txt","w"）;//fs.closeSync = function（fd）fs.closeSync（fd）;//异步读写//fs.open = function（path, flags, mode, callback_）//fs.close = function（fd, callback）fs.open（"data/openColse1.txt","w",function（err,fd） {if （！err）{fs.close（fd,function（）{console.log（"closed"）;}）;}}）;

其中的flags其他语言也会有.其实主要分3部分 r、w、a.和C中的差不多。
1.r —— 以只读方式打开文件，数据流的初始位置在文件开始
2.r+ —— 以可读写方式打开文件，数据流的初始位置在文件开始
3.w ——如果文件存在，则将文件长度清0，即该文件内容会丢失。如果不存在，则尝试创建它。数据流的初始位置在文件开始
4.w+ —— 以可读写方式打开文件，如果文件不存在，则尝试创建它，如果文件存在，则将文件长度清0，即该文件内容会丢失。数据流的初始位置在文件开始
5.a —— 以只写方式打开文件，如果文件不存在，则尝试创建它，数据流的初始位置在文件末尾，随后的每次写操作都会将数据追加到文件后面。
6.a+ ——以可读写方式打开文件，如果文件不存在，则尝试创建它，数据流的初始位置在文件末尾，随后的每次写操作都会将数据追加到文件后面。
二、读写
1.简单文件读写

/** * Created by Administrator on 2016/3/21. */var fs = require（"fs"）;var config = {maxFiles: 20,maxConnections: 15,rootPath: "/webroot"};var configTxt = JSON.stringify（config）;var options = {encoding:"utf8", flag:"w"};//options 定义字符串编码 打开文件使用的模式 标志的encoding、mode、flag属性 可选//异步//fs.writeFile = function（path, data, options, callback_）//同步//fs.writeFileSync = function（path, data, options）fs.writeFile（"data/config.txt", configTxt, options, function（err）{if （err）{console.log（"Config Write Failed."）;} else {console.log（"Config Saved."）;readFile（）;}}）;function readFile（）{var fs = require（"fs"）;var options = {encoding:"utf8", flag:"r"};//异步//fs.readFile = function（path, options, callback_）//同步//fs.readFileSync = function（path, options）fs.readFile（"data/config.txt", options, function（err, data）{if （err）{console.log（"Failed to open Config File."）;} else {console.log（"Config Loaded."）;var config = JSON.parse（data）;console.log（"Max Files: " + config.maxFiles）;console.log（"Max Connections: " + config.maxConnections）;console.log（"Root Path: " + config.rootPath）;}}）;}

"C:Program Files （x86）JetBrainsWebStorm 11.0.3in
unnerw.exe" F:
odejs
ode.exe SimpleReadWrite.jsConfig Saved.Config Loaded.Max Files: 20Max Connections: 15Root Path: /webrootProcess finished with exit code 0

2.同步读写

/** * Created by Administrator on 2016/3/21. */var fs = require（"fs"）;var veggieTray = ["carrots", "celery", "olives"];fd = fs.openSync（"data/veggie.txt", "w"）;while （veggieTray.length）{veggie = veggieTray.pop（） + " ";//系统api //fd 文件描述 第二个参数是被写入的String或Buffer// offset是第二个参数开始读的索引 null是表示当前索引//length 写入的字节数 null一直写到数据缓冲区末尾//position 指定在文件中开始写入的位置 null 文件当前位置// fs.writeSync（fd, buffer, offset, length[, position]）;// fs.writeSync（fd, string[, position[, encoding]]）;//fs.writeSync = function（fd, buffer, offset, length, position）var bytes = fs.writeSync（fd, veggie, null, null）;console.log（"Wrote %s %dbytes", veggie, bytes）;}fs.closeSync（fd）;var fs = require（"fs"）;fd = fs.openSync（"data/veggie.txt", "r"）;var veggies = "";do {var buf = new Buffer（5）;buf.fill（）;//fs.readSync = function（fd, buffer, offset, length, position）var bytes = fs.readSync（fd, buf, null, 5）;console.log（"read %dbytes", bytes）;veggies += buf.toString（）;} while （bytes > 0）;fs.closeSync（fd）;console.log（"Veggies: " + veggies）;

"C:Program Files （x86）JetBrainsWebStorm 11.0.3in
unnerw.exe" F:
odejs
ode.exe syncReadWrite.jsWrote olives 7bytesWrote celery 7bytesWrote carrots 8bytesread 5bytesread 5bytesread 5bytesread 5bytesread 2bytesread 0bytesVeggies: olives celery carrots Process finished with exit code 0

3.异步读写和同步读写的参数差不多就是多了callback

/** * Created by Administrator on 2016/3/21. */var fs = require（"fs"）;var fruitBowl = ["apple", "orange", "banana", "grapes"];function writeFruit（fd）{if （fruitBowl.length）{var fruit = fruitBowl.pop（） + " "; // fs.write（fd, buffer, offset, length[, position], callback）; // fs.write（fd, string[, position[, encoding]], callback）; // fs.write = function（fd, buffer, offset, length, position, callback）fs.write（fd, fruit, null, null, function（err, bytes）{if （err）{console.log（"File Write Failed."）;} else {console.log（"Wrote: %s %dbytes", fruit, bytes）;writeFruit（fd）;}}）;} else {fs.close（fd）;ayncRead（）;}}fs.open（"data/fruit.txt", "w", function（err, fd）{writeFruit（fd）;}）;function ayncRead（）{var fs = require（"fs"）;function readFruit（fd, fruits）{var buf = new Buffer（5）;buf.fill（）;//fs.read = function（fd, buffer, offset, length, position, callback）fs.read（fd, buf, 0, 5, null, function（err, bytes, data）{if （ bytes > 0） {console.log（"read %dbytes", bytes）;fruits += data;readFruit（fd, fruits）;} else {fs.close（fd）;console.log （"Fruits: %s", fruits）;}}）;}fs.open（"data/fruit.txt", "r", function（err, fd）{readFruit（fd, ""）;}）;}

"C:Program Files （x86）JetBrainsWebStorm 11.0.3in
unnerw.exe" F:
odejs
ode.exe asyncReadWrite.jsWrote: grapes 7bytesWrote: banana 7bytesWrote: orange 7bytesWrote: apple 6bytesread 5bytesread 5bytesread 5bytesread 5bytesread 5bytesread 2bytesFruits: grapes banana orange appleProcess finished with exit code 0

4.流式读写

/** * Created by Administrator on 2016/3/21. */var fs = require（"fs"）;var grains = ["wheat", "rice", "oats"];var options = { encoding: "utf8", flag: "w" };//从下面的系统api可以看到 createWriteStream 就是创建了一个writable流//fs.createWriteStream = function（path, options） {//return new WriteStream（path, options）;//};////util.inherits（WriteStream, Writable）;//fs.WriteStream = WriteStream;//function WriteStream（path, options）var fileWriteStream = fs.createWriteStream（"data/grains.txt", options）;fileWriteStream.on（"close", function（）{console.log（"File Closed."）;//流式读streamRead（）;}）;while （grains.length）{var data = grains.pop（） + " ";fileWriteStream.write（data）;console.log（"Wrote: %s", data）;}fileWriteStream.end（）;//流式读function streamRead（）{var fs = require（"fs"）;var options = { encoding: "utf8", flag: "r" };//fs.createReadStream = function（path, options） {//return new ReadStream（path, options）;//};////util.inherits（ReadStream, Readable）;//fs.ReadStream = ReadStream;////function ReadStream（path, options）//createReadStream 就是创建了一个readable流var fileReadStream = fs.createReadStream（"data/grains.txt", options）;fileReadStream.on（"data", function（chunk） {console.log（"Grains: %s", chunk）;console.log（"Read %d bytes of data.", chunk.length）;}）;fileReadStream.on（"close", function（）{console.log（"File Closed."）;}）;}

"C:Program Files （x86）JetBrainsWebStorm 11.0.3in
unnerw.exe" F:
odejs
ode.exe StreamReadWrite.jsWrote: oats Wrote: rice Wrote: wheat File Closed.Grains: oats rice wheat Read 16 bytes of data.File Closed.Process finished with exit code 0

个人觉得像这些api用一用感受一下就ok了,遇到了会用就行了。