Node.js和其他語言一樣,也有文件操作。先不說node.js中的文件操作,其他語言的文件操作一般也都是有打開、關閉、讀、寫、文件信息、新建刪除目錄、刪除文件、檢測文件路徑等。在node.js中也是一樣,也都是這些功能,可能就是api與其他語言不太一樣。
一、同步、異步打開關閉
/**
* Created by Administrator on 2016/3/21.
*/
var fs=require("fs");
//同步讀 fs.openSync = function(path, flags, mode)
//模塊fs.js文件中如上面定義的openSync 函數(shù)3個參數(shù)
//.1.path 文件路徑
//2.flags 打開文件的模式
//3.model 設置文件訪問模式
//fd文件描述
var fd=fs.openSync("data/openClose.txt",'w');
//fs.closeSync = function(fd)
fs.closeSync(fd);
//異步讀寫
//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其他語言也會有.其實主要分3部分 r、w、a.和C中的差不多。
1.r —— 以只讀方式打開文件，數(shù)據(jù)流的初始位置在文件開始
2.r+ —— 以可讀寫方式打開文件，數(shù)據(jù)流的初始位置在文件開始
3.w ——如果文件存在，則將文件長度清0，即該文件內(nèi)容會丟失。如果不存在，則嘗試創(chuàng)建它。數(shù)據(jù)流的初始位置在文件開始
4.w+ —— 以可讀寫方式打開文件，如果文件不存在，則嘗試創(chuàng)建它，如果文件存在，則將文件長度清0，即該文件內(nèi)容會丟失。數(shù)據(jù)流的初始位置在文件開始
5.a —— 以只寫方式打開文件，如果文件不存在，則嘗試創(chuàng)建它，數(shù)據(jù)流的初始位置在文件末尾，隨后的每次寫操作都會將數(shù)據(jù)追加到文件后面。
6.a+ ——以可讀寫方式打開文件，如果文件不存在，則嘗試創(chuàng)建它，數(shù)據(jù)流的初始位置在文件末尾，隨后的每次寫操作都會將數(shù)據(jù)追加到文件后面。
二、讀寫
1.簡單文件讀寫
/**
* 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 定義字符串編碼 打開文件使用的模式 標志的encoding、mode、flag屬性 可選
//異步
//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'};
//異步
//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)\JetBrains\WebStorm 11.0.3\bin\runnerw.exe" F:\nodejs\node.exe SimpleReadWrite.js
Config Saved.
Config Loaded.
Max Files: 20
Max Connections: 15
Root Path: /webroot
Process finished with exit code 0
2.同步讀寫
/**
* 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() + " ";
//系統(tǒng)api
//fd 文件描述 第二個參數(shù)是被寫入的String或Buffer
// offset是第二個參數(shù)開始讀的索引 null是表示當前索引
//length 寫入的字節(jié)數(shù) null一直寫到數(shù)據(jù)緩沖區(qū)末尾
//position 指定在文件中開始寫入的位置 null 文件當前位置
// 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)\JetBrains\WebStorm 11.0.3\bin\runnerw.exe" F:\nodejs\node.exe syncReadWrite.js
Wrote olives 7bytes
Wrote celery 7bytes
Wrote carrots 8bytes
read 5bytes
read 5bytes
read 5bytes
read 5bytes
read 2bytes
read 0bytes
Veggies: olives celery carrots
Process finished with exit code 0
3.異步讀寫 和同步讀寫的參數(shù)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)\JetBrains\WebStorm 11.0.3\bin\runnerw.exe" F:\nodejs\node.exe asyncReadWrite.js
Wrote: grapes 7bytes
Wrote: banana 7bytes
Wrote: orange 7bytes
Wrote: apple 6bytes
read 5bytes
read 5bytes
read 5bytes
read 5bytes
read 5bytes
read 2bytes
Fruits: grapes banana orange apple
Process finished with exit code 0
4.流式讀寫
/**
* Created by Administrator on 2016/3/21.
*/
var fs = require('fs');
var grains = ['wheat', 'rice', 'oats'];
var options = { encoding: 'utf8', flag: 'w' };
//從下面的系統(tǒng)api可以看到 createWriteStream 就是創(chuàng)建了一個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.");
//流式讀
streamRead();
});
while (grains.length){
var data = grains.pop() + " ";
fileWriteStream.write(data);
console.log("Wrote: %s", data);
}
fileWriteStream.end();
//流式讀
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 就是創(chuàng)建了一個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)\JetBrains\WebStorm 11.0.3\bin\runnerw.exe" F:\nodejs\node.exe StreamReadWrite.js
Wrote: oats
Wrote: rice
Wrote: wheat
File Closed.
Grains: oats rice wheat
Read 16 bytes of data.
File Closed.
Process finished with exit code 0
個人覺得像這些api用一用感受一下就ok了,遇到了會用就行了。