C# 多线程窗体的创建

　　从目前已经在项目中工作将近一个月来的情况来看，凡是费时的操作，基本上都要用到多线程的等待窗体、进度提示窗体等实时显示动态的进度信息。而如果直接在主线程的窗体上实时更新信息，就会造成更新太快或者太慢而出现的进程假死现象。为了缓解这些情况，本文就参考一些文章，把他们的智慧总结于此。希望对大家有所帮助。

一、多线程中创建等待窗体

 　　在winform程序开发中，计算机经常会执行一些比较耗时的任务，如大量数据的查询操作、较为复杂的业务处理等，这些任务往往需要耗时几秒到几十秒钟的时间，在这些任务执行期间winform程序窗体不再响应任何鼠标和键盘事件，出现假死状态，用户体验很差。

　　一个比较好的解决办法是，在这些任务执行期间在界面前端显示一个等待窗体，告诉用户任务正在执行中。

1.1 开发等待窗体

窗体中有一个PictureBox控件和两个Lable控件，PictureBox控件的Image属性为一张动态图片。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Threading;
using NavManager.Common;

namespace NavManager.Utils
{
    public partial class WaitForm : Form
    {
        public WaitForm()
        {            
            InitializeComponent();
            SetText("");
        }

        private delegate void SetTextHandler(string text);
        public void SetText(string text)
        {
            if (this.label2.InvokeRequired)
            {
                this.Invoke(new SetTextHandler(SetText), text);
            }
            else
            {
                this.label2.Text = text;
            }
        }
    }
}

1.2 提供访问等待窗体的接口

编写类WaitFormService

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
using System.Windows.Forms;

namespace NavManager.Utils
{
    /// <summary>
    /// Using Singleton Design Pattern
    /// </summary>
    public class WaitFormService
    {
        public static void CreateWaitForm()
        {
            WaitFormService.Instance.CreateForm();
        }

        public static void CloseWaitForm()
        {
            WaitFormService.Instance.CloseForm();
        }

        public static void SetWaitFormCaption(string text)
        {
            WaitFormService.Instance.SetFormCaption(text);
        }

        private static WaitFormService _instance;
        private static readonly Object syncLock = new Object();

        public static WaitFormService Instance
        {
            get 
            {
                if (WaitFormService._instance == null)
                {
                    lock (syncLock)
                    {
                        if (WaitFormService._instance == null)
                        {
                            WaitFormService._instance = new WaitFormService();
                        }
                    }
                }
                return WaitFormService._instance;
            }
        }

        private WaitFormService()
        {
        }

        private Thread waitThread;
        private WaitForm waitForm;

        public void CreateForm()
        {
            if (waitThread != null)
            {
                try
                {
                    waitThread.Abort();
                }
                catch (Exception)
                {
                }
            }

            waitThread = new Thread(new ThreadStart(delegate()
            {
                waitForm = new WaitForm();
                Application.Run(waitForm);
            }));
            waitThread.Start();
        }

        public void CloseForm()
        {
            if (waitThread != null)
            {
                try
                {
                    waitThread.Abort();
                }
                catch (Exception)
                {
                }
            }
        }

        public void SetFormCaption(string text)
        {
            if (waitForm != null)
            {
                try
                {
                    waitForm.SetText(text);
                }
                catch (Exception)
                {
                }
            }
        }

    }
}

1.3 使用WaitFormService提供的接口

 try
    {
        WaitFormService.CreateWaitForm();
        Assembly asmb = Assembly.GetExecutingAssembly();
        Object obj = asmb.CreateInstance(className);
        Form frm = obj as Form;
        this.ShowMenu(frm);
        WaitFormService.CloseWaitForm();
    }
    catch (Exception ex)
    {
        WaitFormService.CloseWaitForm();
    }

参考文章

1. 飘落纸飞机，C# winform 多线程中创建等待窗体，2011。