关于使用fs.readdir进行异步目录搜索有什么想法吗?我意识到我们可以引入递归,并调用read目录函数来读取下一个目录,但我有点担心它不是异步的…
什么好主意吗?我已经看了node-walk,它很棒,但它不能像readdir那样只给我数组中的文件。虽然
寻找这样的输出…
['file1.txt', 'file2.txt', 'dir/file3.txt']
关于使用fs.readdir进行异步目录搜索有什么想法吗?我意识到我们可以引入递归,并调用read目录函数来读取下一个目录,但我有点担心它不是异步的…
什么好主意吗?我已经看了node-walk,它很棒,但它不能像readdir那样只给我数组中的文件。虽然
寻找这样的输出…
['file1.txt', 'file2.txt', 'dir/file3.txt']
当前回答
我最近编写了这个代码,并认为在这里分享它是有意义的。代码使用了异步库。
var fs = require('fs');
var async = require('async');
var scan = function(dir, suffix, callback) {
fs.readdir(dir, function(err, files) {
var returnFiles = [];
async.each(files, function(file, next) {
var filePath = dir + '/' + file;
fs.stat(filePath, function(err, stat) {
if (err) {
return next(err);
}
if (stat.isDirectory()) {
scan(filePath, suffix, function(err, results) {
if (err) {
return next(err);
}
returnFiles = returnFiles.concat(results);
next();
})
}
else if (stat.isFile()) {
if (file.indexOf(suffix, file.length - suffix.length) !== -1) {
returnFiles.push(filePath);
}
next();
}
});
}, function(err) {
callback(err, returnFiles);
});
});
};
你可以这样使用它:
scan('/some/dir', '.ext', function(err, files) {
// Do something with files that ends in '.ext'.
console.log(files);
});
其他回答
There are basically two ways of accomplishing this. In an async environment you'll notice that there are two kinds of loops: serial and parallel. A serial loop waits for one iteration to complete before it moves onto the next iteration - this guarantees that every iteration of the loop completes in order. In a parallel loop, all the iterations are started at the same time, and one may complete before another, however, it is much faster than a serial loop. So in this case, it's probably better to use a parallel loop because it doesn't matter what order the walk completes in, just as long as it completes and returns the results (unless you want them in order).
一个平行循环看起来是这样的:
var fs = require('fs');
var path = require('path');
var walk = function(dir, done) {
var results = [];
fs.readdir(dir, function(err, list) {
if (err) return done(err);
var pending = list.length;
if (!pending) return done(null, results);
list.forEach(function(file) {
file = path.resolve(dir, file);
fs.stat(file, function(err, stat) {
if (stat && stat.isDirectory()) {
walk(file, function(err, res) {
results = results.concat(res);
if (!--pending) done(null, results);
});
} else {
results.push(file);
if (!--pending) done(null, results);
}
});
});
});
};
一个串行循环看起来像这样:
var fs = require('fs');
var path = require('path');
var walk = function(dir, done) {
var results = [];
fs.readdir(dir, function(err, list) {
if (err) return done(err);
var i = 0;
(function next() {
var file = list[i++];
if (!file) return done(null, results);
file = path.resolve(dir, file);
fs.stat(file, function(err, stat) {
if (stat && stat.isDirectory()) {
walk(file, function(err, res) {
results = results.concat(res);
next();
});
} else {
results.push(file);
next();
}
});
})();
});
};
并且在你的主目录中测试它(警告:如果你的主目录中有很多东西,结果列表将会非常大):
walk(process.env.HOME, function(err, results) {
if (err) throw err;
console.log(results);
});
编辑:改进的示例。
它使用了节点8中最多的新功能,包括Promises、util/promisify、destructuring、async-await、map+reduce等等,让你的同事在试图弄清楚发生了什么时挠头。
节点 8+
没有外部依赖。
const { promisify } = require('util');
const { resolve } = require('path');
const fs = require('fs');
const readdir = promisify(fs.readdir);
const stat = promisify(fs.stat);
async function getFiles(dir) {
const subdirs = await readdir(dir);
const files = await Promise.all(subdirs.map(async (subdir) => {
const res = resolve(dir, subdir);
return (await stat(res)).isDirectory() ? getFiles(res) : res;
}));
return files.reduce((a, f) => a.concat(f), []);
}
使用
getFiles(__dirname)
.then(files => console.log(files))
.catch(e => console.error(e));
节点 10.10+
更新到节点10+,甚至更多的whizbang:
const { resolve } = require('path');
const { readdir } = require('fs').promises;
async function getFiles(dir) {
const dirents = await readdir(dir, { withFileTypes: true });
const files = await Promise.all(dirents.map((dirent) => {
const res = resolve(dir, dirent.name);
return dirent.isDirectory() ? getFiles(res) : res;
}));
return Array.prototype.concat(...files);
}
请注意,从节点11.15.0开始,您可以使用files.flat()而不是array. prototype.concat(…files)来扁平化files数组。
11 +节点
如果你想让所有人都大吃一惊,你可以使用下面使用异步迭代器的版本。除了非常酷之外,它还允许使用者每次提取一个结果,这使得它更适合于真正大的目录。
const { resolve } = require('path');
const { readdir } = require('fs').promises;
async function* getFiles(dir) {
const dirents = await readdir(dir, { withFileTypes: true });
for (const dirent of dirents) {
const res = resolve(dir, dirent.name);
if (dirent.isDirectory()) {
yield* getFiles(res);
} else {
yield res;
}
}
}
用法发生了变化,因为返回类型现在是异步迭代器而不是promise
;(async () => {
for await (const f of getFiles('.')) {
console.log(f);
}
})()
如果有人感兴趣,我在这里写了更多关于异步迭代器的文章:https://qwtel.com/posts/software/async-generators-in-the-wild/
只是简单的散步
let pending = [baseFolderPath]
function walk () {
pending.shift();
// do stuffs width pending[0] and change pending items
if (pending[0]) walk(pending[0])
}
walk(pending[0])
另一个简单而有用的方法
function walkDir(root) {
const stat = fs.statSync(root);
if (stat.isDirectory()) {
const dirs = fs.readdirSync(root).filter(item => !item.startsWith('.'));
let results = dirs.map(sub => walkDir(`${root}/${sub}`));
return [].concat(...results);
} else {
return root;
}
}
为了好玩,这里有一个基于流的版本,它与highland.js streams库一起工作。作者之一是维克多·伍。
###
directory >---m------> dirFilesStream >---------o----> out
| |
| |
+--------< returnPipe <-----------+
legend: (m)erge (o)bserve
+ directory has the initial file
+ dirListStream does a directory listing
+ out prints out the full path of the file
+ returnPipe runs stat and filters on directories
###
_ = require('highland')
fs = require('fs')
fsPath = require('path')
directory = _(['someDirectory'])
mergePoint = _()
dirFilesStream = mergePoint.merge().flatMap((parentPath) ->
_.wrapCallback(fs.readdir)(parentPath).sequence().map (path) ->
fsPath.join parentPath, path
)
out = dirFilesStream
# Create the return pipe
returnPipe = dirFilesStream.observe().flatFilter((path) ->
_.wrapCallback(fs.stat)(path).map (v) ->
v.isDirectory()
)
# Connect up the merge point now that we have all of our streams.
mergePoint.write directory
mergePoint.write returnPipe
mergePoint.end()
# Release backpressure. This will print files as they are discovered
out.each H.log
# Another way would be to queue them all up and then print them all out at once.
# out.toArray((files)-> console.log(files))