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C#源码功能示例：刷新网页、最小化托盘、http get和post请求、配置保存、版权时间限制、定时调用、单实例运行，如果已经运行则激活窗口到最前显示等。

单实例运行激活窗口 调用

using System;using System.Collections.Generic;using System.Linq;using System.Windows.Forms;using System.Threading;namespace HTMLWindowsFormsApplication3{    static class Program    {        /// 
        /// 应用程序的主入口点。        /// 
        [STAThread]        static void Main()        {            Application.EnableVisualStyles();            Application.SetCompatibleTextRenderingDefault(false);            SoftHelper.SoftSingle
   
    (); //单实例运行，已运行则激活窗口           // Application.Run(new Form1());            //bool createdNew;             //Mutex instance= new Mutex(true, "互斥名(保证在本机中唯一)", out createdNew);            //if(createdNew)            //{            //    Application.EnableVisualStyles();            //    Application.SetCompatibleTextRenderingDefault(false);            //    Application.Run(new Form1());            //    instance.ReleaseMutex();            //}            //else            //{            //    MessageBox.Show("已经启动了一个程序，请先退出！", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Error);            //    Application.Exit();            //}        }    }}
   

单实例运行，如果已经运行则激活窗口到最前显示 类

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Diagnostics;using System.Windows.Forms;using System.Runtime.InteropServices;namespace HTMLWindowsFormsApplication3{    public class SoftHelper    {        ///
        /// 该函数设置由不同线程产生的窗口的显示状态        /// 
        /// 窗口句柄        /// 指定窗口如何显示。查看允许值列表，请查阅ShowWlndow函数的说明部分        /// 
   
    如果函数原来可见，返回值为非零；如果函数原来被隐藏，返回值为零
           [DllImport("User32.dll")]        private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);        /// 
        ///  该函数将创建指定窗口的线程设置到前台，并且激活该窗口。键盘输入转向该窗口，并为用户改各种可视的记号。        ///  系统给创建前台窗口的线程分配的权限稍高于其他线程。         /// 
        /// 将被激活并被调入前台的窗口句柄        /// 
   
    如果窗口设入了前台，返回值为非零；如果窗口未被设入前台，返回值为零
           [DllImport("User32.dll")]        private static extern bool SetForegroundWindow(IntPtr hWnd);        private const int SW_SHOWNOMAL = 1;        private static void HandleRunningInstance(Process instance)        {            ShowWindowAsync(instance.MainWindowHandle, SW_SHOWNOMAL);//显示            SetForegroundWindow(instance.MainWindowHandle);//当到最前端        }        private static Process RuningInstance()        {            Process currentProcess = Process.GetCurrentProcess();            Process[] Processes = Process.GetProcessesByName(currentProcess.ProcessName);            foreach (Process process in Processes)            {                if (process.Id != currentProcess.Id)                {                    return process;                }            }            return null;        }        /// 
        /// 程序以单例运行         /// 
        public static void SoftSingle
   
    () where T : Form, new()        {            Process process = RuningInstance();            if (process == null)            {                var mainForm = new T();                Application.Run(mainForm);            }            else            {                HandleRunningInstance(process);            }        }    }}
   

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Windows.Forms;using Microsoft.Win32;using System.Net;using System.IO;namespace HTMLWindowsFormsApplication3{    public partial class Form1 : Form    {        System.Timers.Timer t;        long num=0;        Boolean textBox1HasText = false;//判断输入框是否有文本        Boolean textBox2HasText = false;//判断输入框是否有文本        public Form1()        {            InitializeComponent();        }        private void Form1_Load(object sender, EventArgs e)        {           textBox1.Text= Settings1.Default.url;           textBox2.Text = Settings1.Default.num;           label1.Text = "自动同步" + num + "次";          // button1.Focus();           textBox1_Leave(null, null);           textBox2_Leave(null, null);           // textBox1.Text = "www.baidu.com";           // webBrowser1.Navigate(textBox1.Text.ToString());            SetAutoRun(Application.ExecutablePath, true);            StartRefresh();           // this.Hide();            this.WindowState = FormWindowState.Minimized;            //   notifyIcon1.Visible = false;          //  this.ShowInTaskbar = false;           // limited();        }        public void StartRefresh()        {            int time = 1;            try            {                time = int.Parse(textBox2.Text.ToString());            }            catch { }              t = new System.Timers.Timer(1000 * time);//实例化Timer类，设置间隔时间为10000毫秒；            t.Elapsed += new System.Timers.ElapsedEventHandler(theout);//到达时间的时候执行事件；            t.AutoReset = true;//设置是执行一次（false）还是一直执行(true)；            t.Enabled = true;//是否执行System.Timers.Timer.Elapsed事件；                    }        private void limited()        {            DateTime dt1 = DateTime.Parse("2017-09-20");            if (DateTime.Compare(dt1, DateTime.Now) < 0)            {                MessageBox.Show("试用版已经到期，请联系小黄人软件QQ345139427");                Application.Exit();                 return;            }        }        /// 
        /// 设置应用程序开机自动运行        /// 
        /// 应用程序的文件名          /// 是否自动运行，为false时，取消自动运行        /// 
   
    设置不成功时抛出异常
           public static void SetAutoRun(string fileName, bool isAutoRun)  //SetAutoRun(Application.ExecutablePath,true);        {            RegistryKey reg = null;            try            {                if (!System.IO.File.Exists(fileName))                    throw new Exception("该文件不存在!");                String name = fileName.Substring(fileName.LastIndexOf(@"\") + 1);                reg = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\Windows\CurrentVersion\Run", true);                if (reg == null)                    reg = Registry.LocalMachine.CreateSubKey(@"SOFTWARE\Microsoft\Windows\CurrentVersion\Run");                if (isAutoRun)                    reg.SetValue(name, fileName);                else                    reg.SetValue(name, false);            }            catch (Exception ex)            {                throw new Exception(ex.ToString());            }            finally            {                if (reg != null)                    reg.Close();            }        }        //textBox2获得焦点        private void textBox2_Enter(object sender, EventArgs e)        {            if (textBox2HasText == false)                textBox2.Text = "";            textBox2.ForeColor = Color.Black;        }        //textBox2失去焦点        private void textBox2_Leave(object sender, EventArgs e)        {            if (textBox2.Text == "")            {                textBox2.Text = "多少秒刷新1次？";                textBox2.ForeColor = Color.LightGray;                textBox2HasText = false;            }            else                textBox2HasText = true;        }        //textBox1获得焦点        private void textBox1_Enter(object sender, EventArgs e)        {            if (textBox1HasText == false)                textBox1.Text = "";            textBox1.ForeColor = Color.Black;        }        //textBox1失去焦点        private void textBox1_Leave(object sender, EventArgs e)        {            if (textBox1.Text == "")            {                textBox1.Text = "需要刷新的网址";                textBox1.ForeColor = Color.LightGray;                textBox1HasText = false;            }            else                textBox1HasText = true;        }        private void Form1_SizeChanged(object sender, EventArgs e)        {            if (this.WindowState == FormWindowState.Minimized) //判断是否最小化            {                this.ShowInTaskbar = false; //不显示在系统任务栏                notifyIcon1.Visible = true; //托盘图标可见            }        }        private void notifyIcon1_DoubleClick(object sender, EventArgs e)        {            if (this.WindowState == FormWindowState.Minimized)            {                this.Show();                this.WindowState = FormWindowState.Normal;             //   notifyIcon1.Visible = false;                this.ShowInTaskbar = true;            }        }        private void checkBox1_CheckedChanged(object sender, EventArgs e)        {            if (checkBox1.Checked) //设置            {                SetAutoRun(Application.ExecutablePath, true);            }            else            {                SetAutoRun(Application.ExecutablePath, false);            }        }        private void button1_Click(object sender, EventArgs e)        {            Settings1.Default.url = textBox1.Text.ToString();            Settings1.Default.num=textBox2.Text.ToString();            Settings1.Default.Save();            int time = 1;            try            {                time = int.Parse(textBox2.Text.ToString());            }            catch { }            t.Interval=time*1000;        }        public void theout(object source, System.Timers.ElapsedEventArgs e)        {                //MessageBox.Show("OK!");           // string str=HttpGet(textBox1.Text.ToString(),"");            webBrowser1.Navigate(textBox1.Text.ToString());            num++;            this.Invoke((EventHandler)(delegate{                label1.Text = "自动同步" + num + "次";            }));        }        CookieContainer cookie = new CookieContainer();        private string HttpPost(string Url, string postDataStr)        {            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);            request.Method = "POST";            request.ContentType = "application/x-www-form-urlencoded";            request.ContentLength = Encoding.UTF8.GetByteCount(postDataStr);            request.CookieContainer = cookie;            Stream myRequestStream = request.GetRequestStream();            StreamWriter myStreamWriter = new StreamWriter(myRequestStream, Encoding.GetEncoding("gb2312"));            myStreamWriter.Write(postDataStr);            myStreamWriter.Close();            HttpWebResponse response = (HttpWebResponse)request.GetResponse();            response.Cookies = cookie.GetCookies(response.ResponseUri);            Stream myResponseStream = response.GetResponseStream();            StreamReader myStreamReader = new StreamReader(myResponseStream, Encoding.GetEncoding("utf-8"));            string retString = myStreamReader.ReadToEnd();            myStreamReader.Close();            myResponseStream.Close();            return retString;        }        public string HttpGet(string Url, string postDataStr)        {            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url + (postDataStr == "" ? "" : "?") + postDataStr);            request.Method = "GET";            request.ContentType = "text/html;charset=UTF-8";            HttpWebResponse response = (HttpWebResponse)request.GetResponse();            Stream myResponseStream = response.GetResponseStream();            StreamReader myStreamReader = new StreamReader(myResponseStream, Encoding.GetEncoding("utf-8"));            string retString = myStreamReader.ReadToEnd();            myStreamReader.Close();            myResponseStream.Close();            return retString;        }        private void Form1_FormClosing(object sender, FormClosingEventArgs e)        {            this.WindowState = FormWindowState.Minimized;            e.Cancel = true;                        }        private void 退出ToolStripMenuItem_Click(object sender, EventArgs e)        {            Settings1.Default.url = textBox1.Text.ToString();            Settings1.Default.num = textBox2.Text.ToString();            Settings1.Default.Save();            // 关闭所有的线程            this.Dispose();            this.Close();        }       }}