为什么这个c#代码这么慢？目录/文件搜索和添加所需的优化

Question

我已经编写了一些相当快速的代码,并且自从将其更改为"SearchOption.AllDirectories"后,即使只加载表单/应用程序也需要一分钟.

我能做些什么来使这个应用程序在加载时运行得更快？任何帮助/信息将不胜感激.

谢谢.

private const string path = @"R:\Folder One\Folder Two\Folder Three";

public frmMain()
{
    InitializeComponent();

    ListDirectory(treeView1, path);
    treeView1.SelectedNode = treeView1.Nodes[0];
    treeView1.SelectedNode.Expand();
}

private void ListDirectory(TreeView treeView, string path)
{
    treeView.Nodes.Clear();
    var rootDirectoryInfo = new DirectoryInfo(path);
    treeView.Nodes.Add(CreateDirectoryNode(rootDirectoryInfo));
}

private TreeNode CreateDirectoryNode(DirectoryInfo directoryInfo)
{
    var directoryNode = new TreeNode(directoryInfo.Name);
    foreach (var directory in directoryInfo.GetDirectories())
    {
        if (!directory.Name.Contains("_") 
             && !directory.Name.Contains("Word Versions") 
             && !directory.Name.Contains("Visio Flowcharts"))
        {
            var dirFileCount = directory.EnumerateFiles(
                         "*.pdf", SearchOption.AllDirectories).Count();
            dirFileCount += directory.EnumerateFiles(
                         "*.xls", SearchOption.AllDirectories).Count();
            dirFileCount += directory.EnumerateFiles(
                         "*.doc", SearchOption.AllDirectories).Count();
            dirFileCount += directory.EnumerateFiles(
                         "*.xlsx", SearchOption.AllDirectories).Count();
            dirFileCount += directory.EnumerateFiles(
                         "*.docx", SearchOption.AllDirectories).Count();
            dirFileCount += directory.EnumerateFiles(
                         "~*", SearchOption.AllDirectories).Count();

            if (dirFileCount != 0)
                directoryNode.Nodes.Add(CreateDirectoryNode(directory));
        }
    }

    foreach (var file in directoryInfo.GetFiles())
    {
        if (file.Extension.Equals(".pdf") 
           || file.Extension.Equals(".xls") 
           || file.Extension.Equals(".doc") 
           || file.Extension.Equals(".xlsx") 
           || file.Extension.Equals(".docx"))
        {
            if (!file.Name.Contains("~") 
                        || !file.Name.Contains("$"))
                directoryNode.Nodes.Add(new TreeNode(file.Name));
        }
    }
    return directoryNode;
}

Answer 1

这个:

var dirFileCount = directory.EnumerateFiles("*.pdf", SearchOption.AllDirectories).Count();
dirFileCount += directory.EnumerateFiles("*.xls", SearchOption.AllDirectories).Count();
dirFileCount += directory.EnumerateFiles("*.doc", SearchOption.AllDirectories).Count();
dirFileCount += directory.EnumerateFiles("*.xlsx", SearchOption.AllDirectories).Count();
dirFileCount += directory.EnumerateFiles("*.docx", SearchOption.AllDirectories).Count();
dirFileCount += directory.EnumerateFiles("~*", SearchOption.AllDirectories).Count();

if (dirFileCount != 0)
    directoryNode.Nodes.Add(CreateDirectoryNode(directory));

是完全错的.

每个都EnumerateFiles将重新扫描某种类型文件的所有子目录.更糟糕的是:你在计算你总共拥有多少种类型的文件,但你想要的是"那些扩展名是否有文件"？所以找到第一个文件后.pdf你就可以停下来了.

您应该搜索"*",然后按所需的扩展名进行过滤,停在找到的第一个文件中.

这个

var dirFileCount = from p in directory.EnumerateFiles("*", SearchOption.AllDirectories)
                   let extension = p.Extension
                   where extension.Equals("pdf", StringComparison.OrdinalIgnoreCase) ||
                         extension.Equals("xls", StringComparison.OrdinalIgnoreCase) ||
                         extension.Equals("doc", StringComparison.OrdinalIgnoreCase) ||
                         extension.Equals("xlsx", StringComparison.OrdinalIgnoreCase) ||
                         p.Name.StartsWith("~")
                   select p;

if (dirFileCount.Any())
{
    directoryNode.Nodes.Add(CreateDirectoryNode(directory));
}

可能更好.

你确定你必须在子文件夹中搜索吗？因为SearchOption.AllDirectories将在子文件夹中搜索,而不仅仅在给定的文件夹中搜索.