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
}
}