纯异步nodejs文件夹(目录)复制功能

node.js 复制文件夹

思路:

1、callback 驱动

2、递归所有需要复制文件

3、在一定阀值下并发复制文件

var async = require("async"); 
var fs = require("fs"); 
var path = require("path"); 
// cursively make dir 
function mkdirs(p, mode, f, made) { 
 if (typeof mode === 'function' || mode === undefined) { 
 f = mode; 
 mode = 0777 & (~process.umask()); 
 } 
 if (!made) 
 made = null; 
 var cb = f || function () {}; 
 if (typeof mode === 'string') 
 mode = parseInt(mode, 8); 
 p = path.resolve(p); 
 fs.mkdir(p, mode, function (er) { 
 if (!er) { 
 made = made || p; 
 return cb(null, made); 
 } 
 switch (er.code) { 
 case 'ENOENT': 
 mkdirs(path.dirname(p), mode, function (er, made) { 
 if (er) { 
 cb(er, made); 
 } else { 
 mkdirs(p, mode, cb, made); 
 } 
 }); 
 break; 
 // In the case of any other error, just see if there's a dir 
 // there already. If so, then hooray! If not, then something 
 // is borked. 
 default: 
 fs.stat(p, function (er2, stat) { 
 // if the stat fails, then that's super weird. 
 // let the original error be the failure reason. 
 if (er2 || !stat.isDirectory()) { 
 cb(er, made); 
 } else { 
 cb(null, made) 
 }; 
 }); 
 break; 
 } 
 }); 
} 
// single file copy 
function copyFile(file, toDir, cb) { 
 async.waterfall([ 
 function (callback) { 
 fs.exists(toDir, function (exists) { 
 if (exists) { 
 callback(null, false); 
 } else { 
 callback(null, true); 
 } 
 }); 
 }, function (need, callback) { 
 if (need) { 
 mkdirs(path.dirname(toDir), callback); 
 } else { 
 callback(null, true); 
 } 
 }, function (p, callback) { 
 var reads = fs.createReadStream(file); 
 var writes = fs.createWriteStream(path.join(path.dirname(toDir), path.basename(file))); 
 reads.pipe(writes); 
 //don't forget close the when all the data are read 
 reads.on("end", function () { 
 writes.end(); 
 callback(null); 
 }); 
 reads.on("error", function (err) { 
 console.log("error occur in reads"); 
 callback(true, err); 
 }); 
 } 
 ], cb); 
} 
// cursively count the files that need to be copied 
function _ccoutTask(from, to, cbw) { 
 async.waterfall([ 
 function (callback) { 
 fs.stat(from, callback); 
 }, 
 function (stats, callback) { 
 if (stats.isFile()) { 
 cbw.addFile(from, to); 
 callback(null, []); 
 } else if (stats.isDirectory()) { 
 fs.readdir(from, callback); 
 } 
 }, 
 function (files, callback) { 
 if (files.length) { 
 for (var i = 0; i < files.length; i++) { 
 _ccoutTask(path.join(from, files[i]), path.join(to, files[i]), cbw.increase()); 
 } 
 } 
 callback(null); 
 } 
 ], cbw); 
} 
// wrap the callback before counting 
function ccoutTask(from, to, cb) { 
 var files = []; 
 var count = 1; 
 function wrapper(err) { 
 count--; 
 if (err || count <= 0) { 
 cb(err, files) 
 } 
 } 
 wrapper.increase = function () { 
 count++; 
 return wrapper; 
 } 
 wrapper.addFile = function (file, dir) { 
 files.push({ 
 file : file, 
 dir : dir 
 }); 
 } 
 _ccoutTask(from, to, wrapper); 
} 
function copyDir(from, to, cb) { 
 if(!cb){ 
 cb=function(){}; 
 } 
 async.waterfall([ 
 function (callback) { 
 fs.exists(from, function (exists) { 
 if (exists) { 
 callback(null, true); 
 } else { 
 console.log(from + " not exists"); 
 callback(true); 
 } 
 }); 
 }, 
 function (exists, callback) { 
 fs.stat(from, callback); 
 }, 
 function (stats, callback) { 
 if (stats.isFile()) { 
 // one file copy 
 copyFile(from, to, function (err) { 
 if (err) { 
 // break the waterfall 
 callback(true); 
 } else { 
 callback(null, []); 
 } 
 }); 
 } else if (stats.isDirectory()) { 
 ccoutTask(from, to, callback); 
 } 
 }, 
 function (files, callback) { 
 // prevent reaching to max file open limit 
 async.mapLimit(files, 10, function (f, cb) { 
 copyFile(f.file, f.dir, cb); 
 }, callback); 
 } 
 ], cb); 
} 
var start = new Date().getTime(); 
copyDir("F:\\gear", "F:\\gear2", function (err) { 
 if (err) { 
 console.log("error ocur"); 
 console.dir(err); 
 } else { 
 console.log("copy ok"); 
 console.log("consume time:" + (new Date().getTime() - start)) 
 } 
});

总结

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