C#~使用FileSystemWatcher来监视文件系统的变化

对于一个文件夹的改变，C#这边有自己的类来实现，我们不需要关心它的内部实现机制，不需要关心它底层调用哪些API，我们只需要关心如何去调用它，如何让它帮助我们记录文件夹的修改情况即可。

   #region 监视文件夹的变化
            FileSystemWatcher watcher = new FileSystemWatcher();
            watcher.Path = "f:\\";
            watcher.NotifyFilter =//被监控的方面
               NotifyFilters.LastWrite |
               NotifyFilters.FileName |
               NotifyFilters.DirectoryName;

            // 订阅一些事件，当它被触发时（.net(windows)底层触发它，我们不用管），执行我们的方法
            watcher.Changed += (object source, FileSystemEventArgs e) =>
            {
                Console.WriteLine("文件{0}已经被修改,修改类型{1}", e.FullPath, e.ChangeType.ToString());
            };
            watcher.Created += (object source, FileSystemEventArgs e) =>
            {
                Console.WriteLine("文件{0}被建立", e.FullPath);
            };
            watcher.Deleted += (object source, FileSystemEventArgs e) =>
            {
                Console.WriteLine("文件{0}已经被删除", e.FullPath);
            };
            watcher.Renamed += (object source, RenamedEventArgs e) =>
            {
                Console.WriteLine("文件{0}的名称已经从{1}变成了{2}", e.OldFullPath, e.OldName, e.Name);
            };

            // 为true表示开启FileSystemWatcher组件，反之我们的监控将不启作用
            watcher.EnableRaisingEvents = true;
            #endregion

另外，告诉大家一个 xor异或运算的使用技巧，就是它可以在不引入第三个变量的情况下，交替两个变量的值，你的变量可以是数值，也可以是字符，如果是字符，我们需要使用它的hashcode值进行xor运算。

           #region xor两个变量交换
            int a = 2;
            int b = 3;
            Console.WriteLine("a={0}", a);
            Console.WriteLine("b={0}", b);
            a = a ^ b ^ (b = a);
            Console.WriteLine("a={0}", a);
            Console.WriteLine("b={0}", b);
            #endregion

结果如图：

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