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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