C#中的多线程使用 -- Thread 类: 使用回调函数从一个线程中检索数据

下面为一个完整的实例:

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

namespace conThreadCallBack
{
    class Program
    {
        static void Main(string[] args)
        {
            Program pro = new Program();
            ThreadWithState tws = new ThreadWithState("你好吗?", pro.ResultCallBack);
            Thread th = new Thread(tws.ThreadProc);
            th.Start();
            Console.WriteLine("主线程: 开始执行, 等待新线程 ...");
            th.Join();  //等待线程 th 执行完毕后, 再执行主线程中的后面的语句.
            Console.WriteLine("主线程: 新线程执行完毕.");

            Console.ReadKey();
        }
// 回调方法

        private void ResultCallBack(string message)
        {
            Console.WriteLine("主线程: 传回的消息: {0}", message);
        }
    }

    public delegate void CallBackDelegate(string message);

    public class ThreadWithState
    {
        private string Message;
        // 回调委托
        private CallBackDelegate callback;

        // 构造函数
        public ThreadWithState(string message, CallBackDelegate callbackDelegate)
        {
            this.Message = message;
            this.callback = callbackDelegate;
        }

        // 线程方法
        public void ThreadProc()
        {
            Console.WriteLine("新线程: 开始执行 ..");
            Console.WriteLine("新线程: 传入的消息: {0}", Message);
            if (callback != null) callback("谢谢, 我很好呀!");  // 通过委托, 将数据回传给回调函数
        }

    }

}

按照上面的例子, 在实际应用中一个比较复杂的示例如下:

    public partial class FormMain : Form
    {        
        ...

        // 获取轨迹数据(当天) : 使用线程处理, 有传入参数和 返回数据(委托回调)
        private void btnGetTrack_Click(object sender, EventArgs e)
        {            
            int userid = (int)txtTrackRecUserID.Tag;
            DateTime startTime = DateTime.Today;
            DateTime endTime = DateTime.Now;

            CallBackTrackInfo callInfo = new CallBackTrackInfo(userid, startTime, endTime, UpdateTrackInfoList);
            Thread getTrackThread = new Thread(callInfo.ThreadProc);
            getTrackThread.Start();
            //getTrackThread.Join(); // 等返回数据后

        }

        private void UpdateTrackInfoList(List<VehicleGPSInfo> trackInfo) // 回调委托获得数据
        {
            listViewTrackRec.Clear();
            for (int i = 0; i < trackInfo.Count; i++)
            {
                VehicleGPSInfo recItem = trackInfo[i];
                ListViewItem item = listViewTrackRec.Items.Add(recItem.GpsTime.ToString());
                item.Name = recItem.ID.ToString();
                item.SubItems.Add(String.Format("{0}, {1}", recItem.Lng, recItem.Lat));
                item.SubItems.Add(recItem.Speed.ToString());
                item.SubItems.Add(recItem.Direction);
            }
        }

    }

    public delegate void TrackInfoCallBackDelegate(List<VehicleGPSInfo> trackInfo); //回调委托

    public class CallBackTrackInfo // 带返回数据类
    {
        private int UserID;
        private DateTime StartTime;
        private DateTime EndTime;

        List<VehicleGPSInfo> TrackInfo= null;
        // 回调委托
        private TrackInfoCallBackDelegate callback;
        // 构造函数       
        public CallBackTrackInfo(int userid, DateTime startTime, DateTime endTime, TrackInfoCallBackDelegate callbackDelegate)
        {
            this.UserID = userid;
            this.StartTime = startTime;
            this.EndTime = endTime;
            this.callback = callbackDelegate;
        }

        // 线程方法: 连接数据库, 比较费时
        public void ThreadProc()
        {
            DataTable dt = DalClass.getDbMinuteMile(this.StartTime.ToString(), this.EndTime.ToString(), this.UserID);
            int recCount = dt.Rows.Count;

            if (recCount == 0) return;
            if (recCount > 3500)
            {
                string message = String.Format("在选定时间段内的轨迹个数超出3500个,无法进行回放.\n"
                    + "目前轨迹个数为:{0:d}个,请缩小回放轨迹的时间段,以减少回放轨迹个数.", recCount);
                MessageBox.Show(message);
                return;
            }
            TrackInfo = new List<VehicleGPSInfo>();
            DataRow row = null;
            for (int i = 0; i < recCount; i++)
            {
                row = dt.Rows[i];
                int uid = Convert.ToInt32(row["gpda_user_id"]);
                DateTime gpsTime = Convert.ToDateTime(row["gpda_datetime"]);
                double lat = Convert.ToDouble(row["gpda_latitude"]);
                double lng = Convert.ToDouble(row["gpda_longitude"]);
                short speed = Convert.ToInt16(row["gpda_speed"]);
                short angle = Convert.ToInt16(row["gpda_course"]);
                short fuelValue = Convert.ToInt16(row["gpda_alarm"]);
                uint status = Convert.ToUInt32(row["gpda_status"]);
                VehicleGPSInfo recItem = new VehicleGPSInfo(uid, gpsTime, lng, lat, speed, angle, fuelValue, status);
                TrackInfo.Add(recItem);
            }

            if (callback != null) callback(TrackInfo);  // 通过委托, 将数据回传给回调函数        
        }
    }