ManualResetEvent在多线程循环中的应用

 

　　航班数据获取系统的使命是：在每天的指定时刻去网站抓取数据。当系统开始运行后，将无人看管。因此系统的关键在于两点：一是由于数据量巨大，需要开10个线程去获取数据。二是线程要循环获取数据，保证每一天的指定时刻都会开始获取数据。关键点1在文章lock在多线程中的应用已经完成。故本篇主要完成关键点2。之前在线程的循环问题上徘徊良久，不得其中奥妙。如今，将自己所思所得，与尔等分享，以期共同进步。

　　碰到的问题有这么2个：

　　1、当线程start（）之后，便不能再start（）。

　　解决方法：等线程运行完成，自行结束，然后重新新建线程。

　　2、使用suspend()、resume()，被.net告知，已过时，请用信号量机制。不得已，学习ManualResetEvent()。发现，确实能很方便地解决问题，简单极了。

　　首先，明确概念：ManualResetEvent是线程同步事件，用来通知1个或多个线程 。

　　其次，明确三个重要方法：

　　1）Set（），将事件状态设为终止，允许1个或多个线程继续。

　　2）ReSet()，将事件状态设为非终止，导致1个或多个线程阴止。

　　3）WaitOne()，阻止当前线程，直到当前ManualResetEvent收到信号。

　

　　四个按钮：开始、暂停、继续、退出

 

 

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 System.Data.OracleClient;
using System.Net;
using System.Threading;
using System.Collections;

namespace DataManage
{
    public partial class FlightGet : Form
    {
        public DataTable dt;
        public string sConnectionString = System.Configuration.ConfigurationSettings.AppSettings["ConnectionString"].ToString();
        public Thread tGet;//获取所有AIRLINE的线程
        public Thread tCompare;//指定时间的线程
        public Thread tGetHtml1;//获取网页线程1
        public Thread tGetHtml2;//获取网页线程2
        public Thread tGetHtml3;//获取网页线程3
        public Thread tGetHtml4;//获取网页线程4
        public Thread tGetHtml5;//获取网页线程5
        public Thread tGetHtml6;//获取网页线程6
        public Thread tGetHtml7;//获取网页线程7
        public Thread tGetHtml8;//获取网页线程8
        public Thread tGetHtml9;//获取网页线程9
        public Thread tGetHtml10;//获取网页线程10
        public Hashtable parm;
        public string targetURL;
        public int currcount = 0;
        DataRow newrow;
        System.Object obj = new object();//用于lock的对象
        object objCmd = new object();
        public delegate void AddTxt();//定义UI更新代理
        public delegate void dTxt(int iNum);//更新进度条及航线数量代理
        public delegate void dTime(string sTime);//更新时间的代理
        public delegate void dSetButton(bool sTag);//更新按钮的可用
        bool bPauseTag = false;//暂停标志
        public ManualResetEvent mBegin = new ManualResetEvent(false);
        public FlightGet()
        {
            InitializeComponent();
            SetButtonStart(true);
            SetButtonPause(false);
            SetButtonContinue(false);
        }
        //当前航班
        public void Writting(int iNum)
        {
            if (this.InvokeRequired)
            {
                this.BeginInvoke(new dTxt(Writting), iNum);
            }
            else
            {
                this.tb_flight1.Text = iNum.ToString();
            }
        }
        //剩余航班
        public void LeaveFlight(int iNum)
        {
            if (this.InvokeRequired)
            {
                this.BeginInvoke(new dTxt(LeaveFlight), iNum);
            }
            else
            {
                this.tb_flight2.Text = iNum.ToString();
            }
        }
        //所用时间
        public void UseTime(string sTime)
        {
            if (this.InvokeRequired)
            {
                this.BeginInvoke(new dTime(UseTime), sTime);
            }
            else
            {
                this.tb_time1.Text = sTime;
            }
        }
        //剩余时间
        public void LeaveTime(string sTime)
        {
            if (this.InvokeRequired)
            {
                this.BeginInvoke(new dTime(LeaveTime), sTime);
            }
            else
            {
                this.tb_time2.Text = sTime;
            }
        }
        //进度条过程值
        public void SetBar(int iNum)
        {
            if (this.InvokeRequired)
            {
                this.BeginInvoke(new dTxt(SetBar), iNum);
            }
            else
            {
                this.bar.Value = iNum;
            }
        }
        //进度条开始值
        public void SetBarMin(int iNum)
        {
            if (this.InvokeRequired)
            {
                this.BeginInvoke(new dTxt(SetBarMin), iNum);
            }
            else
            {
                this.bar.Minimum = iNum;
            }
        }
        //进度条最大值
        public void SetBarMax(int iNum)
        {
            if (this.InvokeRequired)
            {
                this.BeginInvoke(new dTxt(SetBarMax), iNum);
            }
            else
            {
                this.bar.Maximum = iNum;
            }
        }
        //进度
        public void SetRate(string sTime)
        {
            if (this.InvokeRequired)
            {
                this.BeginInvoke(new dTime(SetRate), sTime);
            }
            else
            {
                this.l_rate.Text = sTime;
            }
        }
        //开始按钮
        public void SetButtonStart(bool sTag)
        {
            if (this.InvokeRequired)
            {
                this.BeginInvoke(new dSetButton(SetButtonStart), sTag);
            }
            else
            {
                this.btn_start.Enabled = sTag;
            }
        }
        //暂停按钮
        public void SetButtonPause(bool sTag)
        {
            if (this.InvokeRequired)
            {
                this.BeginInvoke(new dSetButton(SetButtonPause), sTag);
            }
            else
            {
                this.btn_pause.Enabled = sTag;
            }
        }
        //继续按钮
        public void SetButtonContinue(bool sTag)
        {
            if (this.InvokeRequired)
            {
                this.BeginInvoke(new dSetButton(SetButtonContinue), sTag);
            }
            else
            {
                this.btn_continue.Enabled = sTag;
            }
        }
        
        
        private void btn_start_Click(object sender, EventArgs e)
        {
            SetButtonStart(false);
            SetButtonPause(false);
            SetButtonContinue(false);

            tCompare = new Thread(new ThreadStart(compare));
            tCompare.IsBackground = true;
            tCompare.Start();
        }
        //暂停
        private void btn_pause_Click(object sender, EventArgs e)
        {
            SetButtonPause(false);
            SetButtonContinue(true);
            mBegin.Reset();//阻止所有线程
        }
       //继续
        private void btn_continue_Click(object sender, EventArgs e)
        {
            SetButtonPause(true);
            SetButtonContinue(false);
            mBegin.Set();//继续所有线程

        }
        //退出
        private void btn_exit_Click(object sender, EventArgs e)
        {     
            this.Close();
        }
        //比对时间，无穷地比对
        public void compare()
        {
            while (1 == 1)
            {
                Application.DoEvents();
                System.DateTime currentTime = new System.DateTime();
                currentTime = System.DateTime.Now;
                int iHour = currentTime.Hour;//当前 时
                int iMinute = currentTime.Minute;//当前 分 
                int iSecond = currentTime.Second;// 当前 秒

                int xHour = int.Parse(tb_hour.Text);//设定 时
                int xMinute = int.Parse(tb_minute.Text);//设定 分
                int xSecond = int.Parse(tb_second.Text);//设定 秒
                if (iHour == xHour && iMinute == xMinute && iSecond == xSecond)//到达指定时间，启动10个线程
                {
                    Thread.Sleep(2000);
                    currcount = 0;//从第一行开始获取
                    SetButtonContinue(true);
                    SetButtonPause(true);
                    
                    tGetHtml1 = new Thread(new ThreadStart(GetHtml));
                    tGetHtml1.IsBackground = true;
                    tGetHtml1.Start();

                    tGetHtml2 = new Thread(new ThreadStart(GetHtml));
                    tGetHtml2.IsBackground = true;
                    tGetHtml2.Start();

                    tGetHtml3 = new Thread(new ThreadStart(GetHtml));
                    tGetHtml3.IsBackground = true;
                    tGetHtml3.Start();

                    tGetHtml4 = new Thread(new ThreadStart(GetHtml));
                    tGetHtml4.IsBackground = true;
                    tGetHtml4.Start();

                    tGetHtml5 = new Thread(new ThreadStart(GetHtml));
                    tGetHtml5.IsBackground = true;
                    tGetHtml5.Start();

                    tGetHtml6 = new Thread(new ThreadStart(GetHtml));
                    tGetHtml6.IsBackground = true;
                    tGetHtml6.Start();

                    tGetHtml7 = new Thread(new ThreadStart(GetHtml));
                    tGetHtml7.IsBackground = true;
                    tGetHtml7.Start();

                    tGetHtml8 = new Thread(new ThreadStart(GetHtml));
                    tGetHtml8.IsBackground = true;
                    tGetHtml8.Start();

                    tGetHtml9 = new Thread(new ThreadStart(GetHtml));
                    tGetHtml9.IsBackground = true;
                    tGetHtml9.Start();

                    tGetHtml10 = new Thread(new ThreadStart(GetHtml));
                    tGetHtml10.IsBackground = true;
                    tGetHtml10.Start();

                    mBegin.Set();//给出信号
                    
                }
                else
                {
                    Thread.Sleep(1000);
                    continue;
                }
            }
        }
        public void GetHtml()
        {
            mBegin.WaitOne();

            int iCountRows = dt.Rows.Count;
            bool flag = false;
            while (true)
            {
                mBegin.WaitOne();//为暂停功能而设
                    lock (obj)
                    {
                        if (currcount < iCountRows) 
                        {
                            newrow = dt.Rows[currcount];
                            currcount = currcount + 1;
                            flag = true;
                        }
                        else
                        {
                            SetButtonPause(false);
                            SetButtonContinue(false);
                            flag = false;
                        }
                        if (flag == false)
                        {
                            break;//跳出while循环，10个线程依次终止
                        }
                    }
                    
                    for (int j = 0; j < int.Parse(tb_dates.Text); j++)
                    {
                        mBegin.WaitOne();//为暂停功能而设
                        //获取网页字符串
                        WebClient wc = new WebClient();
                     　　byte[] myDataBuffer = wc.DownloadData(targetURL);
                     　　string s = System.Text.ASCIIEncoding.Default.GetString(myDataBuffer);
                         …………//获取数据
                    }   
            }   
        }

        private void FlightGet_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (MessageBox.Show("确定关闭？", "关闭确认", MessageBoxButtons.OKCancel, MessageBoxIcon.Question) != DialogResult.OK)
            {
                e.Cancel = true;
            }
            else
            {
                if (tCompare.IsAlive)
                {
                    tCompare.Abort();
                }
                if (tGetHtml1!=null && tGetHtml1.IsAlive)
                {
                    tGetHtml1.Abort();
                }
                if (tGetHtml2!=null && tGetHtml2.IsAlive)
                {
                    tGetHtml2.Abort();
                }
                if (tGetHtml3!=null && tGetHtml3.IsAlive)
                {
                    tGetHtml3.Abort();
                }
                if (tGetHtml4!=null && tGetHtml4.IsAlive)
                {
                    tGetHtml4.Abort();
                }
                if (tGetHtml5!=null && tGetHtml5.IsAlive)
                {
                    tGetHtml5.Abort();
                }
                if (tGetHtml6!=null&& tGetHtml6.IsAlive)
                {
                    tGetHtml6.Abort();
                }
                if (tGetHtml7 !=null && tGetHtml7.IsAlive)
                {
                    tGetHtml7.Abort();
                }
                if (tGetHtml8 !=null && tGetHtml8.IsAlive)
                {
                    tGetHtml8.Abort();
                }
                if (tGetHtml9!=null && tGetHtml9.IsAlive)
                {
                    tGetHtml9.Abort();
                }
                if (tGetHtml10 !=null && tGetHtml10.IsAlive)
                {
                    tGetHtml10.Abort();
                }
            }
        }
       

    }
}