C#利用FileSystemWatcher对文件进行监控

1、打开VS，选择Visual C#模板创建WPF应用程序。输入名称FileSystemWatcherTest，并指定其位置，点击确认按钮进入代码编写界面。

2、准备一个RichTextBox控件拖入到Form1界面中，点击右上角三角形，弹出RichTextBox任务，选择在父容器中停靠。该RichTextBox将用于监控外部记事本改变时显示改动后的内容。

3、添加一个名为MyWatcher的新类。可点击VS菜单项中的【项目】在其下拉菜单中找到【添加类】并点击，弹出添加新项窗口，在点击C#项中【类】，输入名称MyWatcher，点击【添加】按钮

4、在MyWatcher.cs页面中添加复制粘贴如下代码：

using System;

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

namespace FileSystemWatcherTest

{
    class MyWatcher
    {
    
        public MyWatcher(dynamic FormTest,string path)
        {
            this.FormTest = FormTest;
            this.Path = path;
        }
        private  FileSystemWatcher watcher = null;
        private dynamic FormTest;
        internal  string Path
        {
            set
            {
                //watcher.Path = value;
                WatcherStrat(value);
            }
        }
        private  void WatcherStrat(string path)
        {
            if (watcher == null)
            {
                watcher = new FileSystemWatcher();
                System.IO.FileInfo f = new FileInfo(path);
                watcher.Path = f.DirectoryName ;
                watcher.Changed += new FileSystemEventHandler(OnChanged);
                watcher.EnableRaisingEvents = true;
                watcher.NotifyFilter = NotifyFilters.Attributes |
                                       NotifyFilters.CreationTime |
                                       NotifyFilters.DirectoryName |
                                       NotifyFilters.FileName |
                                       NotifyFilters.LastAccess |
                                       NotifyFilters.LastWrite |
                                       NotifyFilters.Security |
                                       NotifyFilters.Size;
                watcher.IncludeSubdirectories = true;
                watcher.Filter ="*"+ f.Extension;
            }
            else
            {
                System.IO.FileInfo f = new FileInfo(path);
                watcher.Path = f.FullName;
                watcher.Filter = "*" + f.Extension;
            }
        }
        private  void OnChanged(object source, FileSystemEventArgs e)
        {
            FormTest.TxtChanged(watcher.Path + "\\" + e.Name);
        }
    }
}

5、在Form1页面中添加复制粘贴如下代码：

using System;

using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace FileSystemWatcherTest

{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            MyWatcher mwatcher = new MyWatcher(this, "1.txt");
        }
        public void TxtChanged(string path)
        {
            System.IO.StreamReader sr = new System.IO.StreamReader(path);
            string str = sr.ReadToEnd();
            sr.Close();
            RichTextBox1Text = str;
        }

        private delegate void RefleshUI(string s);

        private void Thread(string s)//UI线程要做的事情
        {
            this.richTextBox1.Text = s;
        }
        public string RichTextBox1Text
        {
            set
            {
                this.richTextBox1.Invoke(new RefleshUI(Thread), value);
            }
        }
    }
}

6、编译代码，生成解决方案。编译成功后，按F5执行。在生成目录下创建一个TXT文件，并修改其内容后保存，会发现richTextBox1中的内容发生了同样的变化。