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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