导出Excel 或 大量耗时计算时，前端界面保持可操作

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

namespace WinformTest
{
    public partial class frmMain : Form
    {
        public frmMain()
        {
            InitializeComponent();
        }

        #region 运用线程
        /// <summary>
        /// 导出Excel或其他耗时计算
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnExport_Click(object sender, EventArgs e)
        {
            //显示正在计算的动画
            this.pictureBox1.Visible = true;
            //启用另一个线程，完成导出
            Thread t = new Thread(new ParameterizedThreadStart(Export));
            t.Start("sql where");
        }
        /// <summary>
        /// 这里以有参举例
        /// </summary>
        /// <param name="strWhere"></param>
        private void Export(object strWhere)
        {
            Thread.Sleep(1000);
            this.Invoke(new Action(UpdateUI));
        }
        private void UpdateUI()
        {
            this.pictureBox1.Visible = false;
        }
        #endregion

        #region 运用线程池，同时有返回值
        private void btnExportAnother_Click(object sender, EventArgs e)
        {
            //显示正在计算的动画
            this.pictureBox1.Visible = true;
            //使用线程池，来完成导出
            WaitCallback wc = new WaitCallback(this.ExportExcel);
            ThreadPool.QueueUserWorkItem(wc, "sql where");
        }
        private void ExportExcel(object sql)
        {
            Thread.Sleep(1000);
            //这里还以有参举例
            object result = this.Invoke(new Func<int, int>(GetNumber), 11);
            MessageBox.Show(result + "");
        }
        private int GetNumber(int num)
        {
            this.pictureBox1.Visible = false;
            return 1111;
        }
        #endregion

        private void btnTest_Click(object sender, EventArgs e)
        {
            MessageBox.Show("能操作界面");
        }

    }
}