前面的博客 Node.js文件操作一中主要是对文件的读写操作,其实还有文件这块还有一些其他操作.
一、验证文件path是否正确(系统是如下定义的)
fs.exists = function(path, callback) {
if (!nullCheck(path, cb)) return;
var req = new FSReqWrap();
req.oncomplete = cb;
binding.stat(pathModule._makeLong(path), req);
function cb(err, stats) {
if (callback) callback(err ? false : true);
}
};
fs.existsSync = function(path) {
try {
nullCheck(path);
binding.stat(pathModule._makeLong(path));
return true;
} catch (e) {
return false;
}
};
二、获取文件信息
获取文件信息用fs.stats(path,callback)、fs.statsSync(path),它们返回Stats对象.下面是系统定义的Stats对象.
// Static method to set the stats properties on a Stats object.
fs.Stats = function(
dev,
mode,
nlink,
uid,
gid,
rdev,
blksize,
ino,
size,
blocks,
atim_msec,
mtim_msec,
ctim_msec,
birthtim_msec) {
this.dev = dev;
this.mode = mode;
this.nlink = nlink;
this.uid = uid;
this.gid = gid;
this.rdev = rdev;
this.blksize = blksize;
this.ino = ino;
this.size = size;
this.blocks = blocks;
this.atime = new Date(atim_msec);
this.mtime = new Date(mtim_msec);
this.ctime = new Date(ctim_msec);
this.birthtime = new Date(birthtim_msec);
}; // Create a C++ binding to the function which creates a Stats object.
binding.FSInitialize(fs.Stats); fs.Stats.prototype._checkModeProperty = function(property) {
return ((this.mode & constants.S_IFMT) === property);
}; fs.Stats.prototype.isDirectory = function() {
return this._checkModeProperty(constants.S_IFDIR);
}; fs.Stats.prototype.isFile = function() {
return this._checkModeProperty(constants.S_IFREG);
}; fs.Stats.prototype.isBlockDevice = function() {
return this._checkModeProperty(constants.S_IFBLK);
}; fs.Stats.prototype.isCharacterDevice = function() {
return this._checkModeProperty(constants.S_IFCHR);
}; fs.Stats.prototype.isSymbolicLink = function() {
return this._checkModeProperty(constants.S_IFLNK);
}; fs.Stats.prototype.isFIFO = function() {
return this._checkModeProperty(constants.S_IFIFO);
}; fs.Stats.prototype.isSocket = function() {
return this._checkModeProperty(constants.S_IFSOCK);
}; // Don't allow mode to accidentally be overwritten.
['F_OK', 'R_OK', 'W_OK', 'X_OK'].forEach(function(key) {
Object.defineProperty(fs, key, {
enumerable: true, value: constants[key] || 0, writable: false
});
});
通过Stats对象可以获取该文件的信息例如：文件大小、创建时间、文件类型等。
var fs = require('fs');
fs.stat('file_stats.js', function (err, stats) {
if (!err){
console.log('stats: ' + JSON.stringify(stats, null, ' '));
console.log(stats.isFile() ? "Is a File" : "Is not a File");
console.log(stats.isDirectory() ? "Is a Folder" : "Is not a Folder");
console.log(stats.isSocket() ? "Is a Socket" : "Is not a Socket");
stats.isDirectory();
stats.isBlockDevice();
stats.isCharacterDevice();
//stats.isSymbolicLink(); //only lstat
stats.isFIFO();
stats.isSocket();
}
});
"C:\Program Files (x86)\JetBrains\WebStorm 11.0.3\bin\runnerw.exe" F:\nodejs\node.exe file_stats.js
stats: {
"dev": 1086025760,
"mode": 33206,
"nlink": 1,
"uid": 0,
"gid": 0,
"rdev": 0,
"ino": 12384898975555938,
"size": 535,
"atime": "2016-03-12T04:09:24.523Z",
"mtime": "2014-11-10T22:12:29.000Z",
"ctime": "2016-03-21T11:39:54.207Z",
"birthtime": "2016-03-12T04:09:24.523Z"
}
Is a File
Is not a Folder
Is not a Socket Process finished with exit code 0
三、文件遍历
在其他系统也都有文件遍历.由于文件是树的形式存在,所以使用递归遍历.下面是用异步api,那同步api也能推出来。fs.readdirsync(path).
/**
* Created by Administrator on 2016/3/22.
*/
var fs = require('fs');
var Path = require('path');
function WalkDirs(dirPath){
console.log(dirPath);
fs.readdir(dirPath, function(err, entries){
for (var idx in entries){
var fullPath = Path.join(dirPath, entries[idx]);
(function(fullPath){
fs.stat(fullPath, function (err, stats){
if (stats && stats.isFile()){
console.log(fullPath);
} else if (stats && stats.isDirectory()){
WalkDirs(fullPath);
}
});
})(fullPath);
}
});
}
WalkDirs("../");
"C:\Program Files (x86)\JetBrains\WebStorm 11.0.3\bin\runnerw.exe" F:\nodejs\node.exe file_readdir.js
../
..\.idea
..\data
..\asyncReadWrite.js
..\Buffer.js
..\Immediate.js
..\Console.js
..\Interval.js
..\nexttick.txt
..\OpenClose.js
..\StreamReadWrite.js
..\syncReadWrite.js
..\nexttick1.txt
..\.idea\.name
..\.idea\encodings.xml
..\.idea\jsLibraryMappings.xml
..\.idea\misc.xml
..\.idea\modules.xml
..\.idea\NodeJsDemo.iml
..\.idea\workspace.xml
..\nexttick2.txt
..\data\config.txt
..\timer.js
..\SimpleReadWrite.js
..\data\file_readdir.js
..\data\grains.txt
..\data\fruit.txt
..\data\openColse1.txt
..\data\veggie.txt
..\data\openClose.txt Process finished with exit code 0
四、文件删除
根据前面的几个api,删除有fs.unlink(path,callback)那就有fs.unlink(path).
fs.unlink("../nexttick1.txt", function(err){
console.log(err ? "File Delete Failed" : "File Deleted");
});
"C:\Program Files (x86)\JetBrains\WebStorm 11.0.3\bin\runnerw.exe" F:\nodejs\node.exe file_readdir.js
File Deleted Process finished with exit code 0
五、截断文件
截断文件把文件结束设置为比当前小的值来减少文件的大小.
fs.truncate = function(path, len, callback)
fs.truncateSync = function(path, len) 同步返回布尔值
fs.truncate("test.txt",8,function(err){
console.log(err?"File Truncate Failed":"File Truncated")
})
六、建立删除文件夹
刚才是遍历用的是readdir,现在是建立则用fs.mkdir(path,[mode],callback)或fs.mkdirSync(path,[mode])。删除则用fs.rmdir(path,callback)或fs.rmdirSync(path).
fs.mkdir("../test",function(err){
console.log(err?"mkdir Failed":"mkdir success")
if(!err)
{
rmdir();
}
});
function rmdir()
{
fs.rmdir("../test",function(err){
console.log(err?"rmdir Failed":"rmdir success")
});
}
"C:\Program Files (x86)\JetBrains\WebStorm 11.0.3\bin\runnerw.exe" F:\nodejs\node.exe file_readdir.js
mkdir success
rmdir success Process finished with exit code 0
七.文件重命名
这个重命名不只是改变文件的名字,它可以改变文件的路径。
fs.rename("test","../test1",function(err){
console.log(err ? "rename Failed" : "renamed");
})
"C:\Program Files (x86)\JetBrains\WebStorm 11.0.3\bin\runnerw.exe" F:\nodejs\node.exe file_readdir.js
renamed Process finished with exit code 0
八、文件监视
文件发生变化时会执行回调函数.
fs.watchFile("../test1",{persistent:true,interval:5000},function(curr,prev){
console.log(curr.mtime);
console.log(prev.mtime);
});
fs.rename("../test1","test",function(err){
console.log(err ? "rename Failed" : "renamed");
})
"C:\Program Files (x86)\JetBrains\WebStorm 11.0.3\bin\runnerw.exe" F:\nodejs\node.exe file_readdir.js
renamed
Thu Jan 01 1970 08:00:00 GMT+0800 (中国标准时间)
Tue Mar 22 2016 19:30:11 GMT+0800 (中国标准时间)
persistent:持续 interval:时间间隔