java - 如何使用 Java 索引整个硬盘/文件系统？

Question

我想使用Java来获取整个硬盘上的文件更改。例如c:\或/mnt/drives/hdd1

这是一个要求，因为许多不同的计算机使用不同的文件结构，不能轻易更改而不影响其他软件。但应该对特定文件和文件类型建立索引。它们可以存在于驱动器 c:\d:\e:\和任何子文件夹中。

Java WatchService 无法完成这项工作，因为您必须手动添加每个子目录。文件夹数量超过 10+k，这是不可行的，而且速度很慢。

我正在 JAVA 中寻找类似的东西:

C# 和 Java 实现之间的区别:如果我使用管理员权限运行 WatchService Java 代码，我可以访问 c:\$Recycle.Bin，但不能访问 c:\Documents and Settings。我收到拒绝访问异常。有人能告诉我为什么吗？正如我提到的，WatchService 不是解决方案，因为它需要花费大量时间才能爬取所有子目录。对于 10,000 多个文件夹来说，注册每个子文件夹并使用成对的 WatchKey 和 java.nio2.Path 维护一个 Map 是一个非常糟糕的解决方案。

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace FileSystemWatcherTest
{
    class Program
    {
        static void Main(string[] args)
        {
            FileSystemWatcher fileSystemWatcher = new FileSystemWatcher();
            try
            {
                // Watch for changes on this path
                fileSystemWatcher.Path = "c:\\";

                // Watch for changes on all files
                fileSystemWatcher.Filter = "*.*";

                // Also watch for changes within sub directories
                fileSystemWatcher.IncludeSubdirectories = true;

                fileSystemWatcher.Changed += fileSystemWatcher_Changed;
                fileSystemWatcher.Created += fileSystemWatcher_Created;
                fileSystemWatcher.Deleted += fileSystemWatcher_Deleted;
                fileSystemWatcher.Renamed += fileSystemWatcher_Renamed;

                // Begin watching
                fileSystemWatcher.EnableRaisingEvents = true;

            }
            catch (Exception ex)
            {
                Console.WriteLine("An error occurred: " + ex.Message);
            }

            while (true)
            {
                System.Threading.Thread.Sleep(60 * 1000);
            }

        }

        static void fileSystemWatcher_Renamed(object sender, RenamedEventArgs e)
        {
            Console.WriteLine("Rename " + e.FullPath);
        }

        static void fileSystemWatcher_Deleted(object sender, FileSystemEventArgs e)
        {
            Console.WriteLine("Delete " + e.FullPath);
        }

        static void fileSystemWatcher_Created(object sender, FileSystemEventArgs e)
        {
            Console.WriteLine("Create " + e.FullPath);
        }

        static void fileSystemWatcher_Changed(object sender, FileSystemEventArgs e)
        {
            Console.WriteLine("Change " + e.FullPath);
        }
    }
}

JAVA实现:

private void registerDirectoryWithSubfolders(final Path start) throws IOException {
    // register directory and sub-directories
    Files.walkFileTree(start, new SimpleFileVisitor<Path>() {
        @Override
        public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs)
            throws IOException
        {
            System.out.println(dir);
            try
            {
                registerDirectory(dir);
            }
            catch(java.nio.file.AccessDeniedException ex)
            {
                System.err.println("Access Denied: " + dir);
            }
            catch(java.lang.Throwable ex)
            {
                System.err.println("Exception: " + dir);
            }

            return FileVisitResult.CONTINUE;
        }

        @Override
        public FileVisitResult visitFileFailed(Path file, IOException exc)
            throws IOException
        {
            System.err.println("Error And SKIP " + file);
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return FileVisitResult.SKIP_SUBTREE;
        }
    });
}

Answer 1

对我来说，这看起来像是 Monitor subfolders with a Java watch service 的重复项

您可以像这样观看子目录:

/**
 * Register the given directory, and all its sub-directories, with the WatchService.
 */
private void registerAll(final Path start) throws IOException {
    // register directory and sub-directories
    Files.walkFileTree(start, new SimpleFileVisitor<Path>() {
        @Override
        public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs)
            throws IOException {
                dir.register(watcher, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY);
                return FileVisitResult.CONTINUE;
        }
    });
}