DirectoryReaderSync

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关于本文档
基本概念
方法概述
Method
浏览器兼容性
另请参阅
相关话题

非标
此特征是非标准的，且不在标准轨道中。不要在面向 Web 的生产站点中使用它：它不适用于每个用户。实现之间可能存在大的不兼容性，且行为将来可能改变。

DirectoryReaderSync 接口在文件系统 API lets you read the entries in a directory.

This interface has been abandonned: it was on a standard track and it proves not a good idea. Do not use it anymore.

关于本文档

This document was last updated on March 2, 2012 and follows the W3C Specifications (Working Draft) drafted on April 19, 2011.

This specification is pretty much abandoned, having failed to reach any substantial traction.

基本概念

Before you call the only method in this interface, readEntries() , create the DirectoryEntrySync object. But DirectoryEntrySync (as well as FileEntrySync ) is not a data type that you can pass between a calling app and Web Worker thread. It's not a big deal, because you don't really need to have the main app and the worker thread see the same JavaScript object; you just need them to access the same files. You can do that by passing a list of filesystem: URLs—which are just strings—instead of a list of entries. You can also use the filesystem: URL to look up the entry with resolveLocalFileSystemURL() . That gets you back to a DirectoryEntrySync (as well as FileEntrySync) object.

范例

In the following code snippet from HTML5Rocks , we create Web Workers and pass data from it to the main app.

// Taking care of the browser-specific prefixes.
  window.resolveLocalFileSystemURL = window.resolveLocalFileSystemURL ||
                                     window.webkitResolveLocalFileSystemURL;
// Create web workers
  var worker = new Worker('worker.js');
  worker.onmessage = function(e) {
    var urls = e.data.entries;
    urls.forEach(function(url, i) {
      window.resolveLocalFileSystemURL(url, function(fileEntry) {
        // Print out file's name.
        console.log(fileEntry.name);
      });
    });
  };
  worker.postMessage({'cmd': 'list'});

The following is Worker.js code that gets the contents of the directory.

// Taking care of the browser-specific prefixes.
self.requestFileSystemSync = self.webkitRequestFileSystemSync ||
                             self.requestFileSystemSync;
// Global for holding the list of entry file system URLs.
var paths = [];
function getAllEntries(dirReader) {
  var entries = dirReader.readEntries();
  for (var i = 0, entry; entry = entries[i]; ++i) {
    // Stash this entry's filesystem in URL
    paths.push(entry.toURL());
    // If this is a directory, traverse.
    if (entry.isDirectory) {
      getAllEntries(entry.createReader());
    }
  }
}
// Forward the error to main app.
function onError(e) {
  postMessage('ERROR: ' + e.toString());
}
self.onmessage = function(e) {
  var data = e.data;
  // Ignore everything else except our 'list' command.
  if (!data.cmd || data.cmd != 'list') {
    return;
  }
  try {
    var fs = requestFileSystemSync(TEMPORARY, 1024*1024 /*1MB*/);
    getAllEntries(fs.root.createReader());
    self.postMessage({entries: paths});
  } catch (e) {
    onError(e);
  }
};

方法概述


										EntrySync
										
											readEntries
										
										() raises (
										
											FileException
										
										);

方法

readEntries()

Returns a lost of entries from a specific directory. Call this method until an empty array is returned.

EntrySync readEntries (
) raises (FileException);

参数

None

异常

This method can raise a FileException with the following codes:

异常	描述
`NOT_FOUND_ERR`	The directory does not exist.
`INVALID_STATE_ERR`	The directory has been modified since the first call to readEntries was processed.
`SECURITY_ERR`	The browser determined that it was not safe to look up the metadata.

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`DirectoryReaderSync` 非标	Chrome 13 Prefixed 13 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge 79 Prefixed 79 Prefixed Prefixed Implemented with the vendor prefix: webkit	Firefox No	IE No	Opera No	Safari No	WebView Android 37 Prefixed 37 Prefixed Prefixed Implemented with the vendor prefix: webkit	Chrome Android 18 Prefixed 18 Prefixed Prefixed Implemented with the vendor prefix: webkit	Firefox Android No	Opera Android No	Safari iOS No	Samsung Internet Android 1.0 Prefixed 1.0 Prefixed Prefixed Implemented with the vendor prefix: webkit

图例

完整支持
不支持
非标。预期跨浏览器支持较差。
要求使用供应商前缀或不同名称。

另请参阅

规范： File API: Directories and System Specification WD

参考：文件系统 API

介绍： Basic Concepts About the File System API

元数据

最后修改： 2019 年 3 月 23 日

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