c# - 有什么办法让我知道文件是否已被修改？

Question

我正在制作一个程序来检测文件是否已被修改。但该文件不是我提供的。我想知道是否可以知道我收到的文件是否已被修改。

有办法让我知道吗？我尝试过创建日期和修改日期，但有时当我修改文件时，它们的值将是相同的。

附注我没有原始文件。我想知道是否有可能知道我得到的在我得到它之前是否没有改变。

Answer 1

以下示例创建一个 FileSystemWatcher 来监视运行时指定的目录。该组件设置为监视 LastWrite 和 LastAccess 时间的更改以及目录中文本文件的创建、删除或重命名。如果更改、创建或删除文件，该文件的路径将打印到控制台。重命名文件时，旧路径和新路径都会打印到控制台。 本示例使用 System.Diagnostics 和 System.IO 命名空间。

using System;
using System.IO;
using System.Security.Permissions;

public class Watcher
{

    public static void Main()
    {
    Run();

    }

    [PermissionSet(SecurityAction.Demand, Name="FullTrust")]
    public static void Run()
    {
        string[] args = System.Environment.GetCommandLineArgs();

        // If a directory is not specified, exit program.
        if(args.Length != 2)
        {
            // Display the proper way to call the program.
            Console.WriteLine("Usage: Watcher.exe (directory)");
            return;
        }

        // Create a new FileSystemWatcher and set its properties.
        FileSystemWatcher watcher = new FileSystemWatcher();
        watcher.Path = args[1];
        /* Watch for changes in LastAccess and LastWrite times, and
           the renaming of files or directories. */
        watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite
           | NotifyFilters.FileName | NotifyFilters.DirectoryName;
        // Only watch text files.
        watcher.Filter = "*.txt";

        // Add event handlers.
        watcher.Changed += new FileSystemEventHandler(OnChanged);
        watcher.Created += new FileSystemEventHandler(OnChanged);
        watcher.Deleted += new FileSystemEventHandler(OnChanged);
        watcher.Renamed += new RenamedEventHandler(OnRenamed);

        // Begin watching.
        watcher.EnableRaisingEvents = true;

        // Wait for the user to quit the program.
        Console.WriteLine("Press \'q\' to quit the sample.");
        while(Console.Read()!='q');
    }

    // Define the event handlers.
    private static void OnChanged(object source, FileSystemEventArgs e)
    {
        // Specify what is done when a file is changed, created, or deleted.
       Console.WriteLine("File: " +  e.FullPath + " " + e.ChangeType);
    }

    private static void OnRenamed(object source, RenamedEventArgs e)
    {
        // Specify what is done when a file is renamed.
        Console.WriteLine("File: {0} renamed to {1}", e.OldFullPath, e.FullPath);
    }
}

引用:Microsoft MSDN