C#多线程经典示例吃苹果

本文主要讲述了多线程开发中经典示例，通过本示例，可以加深对多线程的理解。

示例概述：

　　下面用一个模拟吃苹果的实例，说明C#中多线程的实现方法。要求开发一个程序实现如下情况：一个家庭有三个孩子，爸爸妈妈不断削苹果往盘子里面放，老大、老二、老三不断从盘子里面取苹果吃。盘子的大小有限，最多只能放5个苹果，并且爸妈不能同时往盘子里面放苹果，妈妈具有优先权。三个孩子取苹果时，盘子不能为空，三人不能同时取，老三优先权最高，老大最低。老大吃的最快，取的频率最高，老二次之。.

涉及知识点：

线程Thread 创建并控制线程，设置其优先级并获取其状态。
锁 lock 用于实现多线程同步的最直接办法就是加锁，它可以把一段代码定义为互斥段，在一个时刻内只允许一个线程进入执行，而其他线程必须等待。
事件EventHandler 声明一个事件，用于通知界面做改变

设计思路：

Productor 表示生产者，用于削苹果。
Consumer 表示消费者，用于吃苹果。
Dish 盘子，用于装苹果，作为中间类
EatAppleSmp 的BeginEat()方法，表示开始吃苹果，启动线程

效果图

如下【爸爸妈妈削苹果，孩子吃苹果】：

C#多线程经典示例吃苹果

核心算法

后台输出如下：

Mama放1个苹果Baba放1个苹果Dage取苹果吃...Erdi取苹果吃...Sandi等待取苹果Mama放1个苹果Sandi取苹果吃...Baba放1个苹果Dage取苹果吃...Mama放1个苹果Baba放1个苹果Erdi取苹果吃...Mama放1个苹果Baba放1个苹果Dage取苹果吃...Sandi取苹果吃...Mama放1个苹果Baba放1个苹果Erdi取苹果吃...Mama放1个苹果Baba放1个苹果Dage取苹果吃...Mama放1个苹果Baba放1个苹果Sandi取苹果吃...Mama放1个苹果Baba正在等待放入苹果Erdi取苹果吃...Baba放1个苹果Dage取苹果吃...Mama放1个苹果Baba正在等待放入苹果Mama正在等待放入苹果Sandi取苹果吃...Baba放1个苹果Mama正在等待放入苹果Erdi取苹果吃...Mama放1个苹果Dage取苹果吃...Baba放1个苹果Mama正在等待放入苹果Dage取苹果吃...Mama放1个苹果Baba正在等待放入苹果Erdi取苹果吃...Baba放1个苹果Sandi取苹果吃...Mama放1个苹果Baba正在等待放入苹果Dage取苹果吃...Baba放1个苹果Mama正在等待放入苹果Erdi取苹果吃...Mama放1个苹果Baba正在等待放入苹果Sandi取苹果吃...Baba放1个苹果Mama正在等待放入苹果Dage取苹果吃...Mama放1个苹果Baba正在等待放入苹果Mama正在等待放入苹果Erdi取苹果吃...Mama放1个苹果Baba正在等待放入苹果Dage取苹果吃...Baba放1个苹果Mama正在等待放入苹果Sandi取苹果吃...Mama放1个苹果Baba正在等待放入苹果Mama正在等待放入苹果线程 'Mama' (0x1ce0) 已退出，返回值为 0 (0x0)。线程 'Baba' (0x1888) 已退出，返回值为 0 (0x0)。Erdi取苹果吃...Dage取苹果吃...Sandi取苹果吃...Dage取苹果吃...Erdi取苹果吃...Dage等待取苹果Sandi等待取苹果Erdi等待取苹果
后台输出

Productor 代码如下：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading;
namespace DemoSharp.EatApple{    /// <summary>    /// 生产者    /// </summary>    public class Productor    {        private Dish dish;        private string name;
        public string Name        {            get { return name; }            set { name = value; }        }
        public EventHandler PutAction;//声明一个事件，当放苹果时触发该事件
        public Productor(string name, Dish dish)        {            this.name = name;            this.dish = dish;        }        public void run()        {            while (true)            {                bool flag= dish.Put(name);                if (flag)                {                    if (PutAction != null)                    {                        PutAction(this, null);                    }                    try                    {                        Thread.Sleep(600);//削苹果时间                    }                    catch (Exception ex)                    {
                    }                }                else {                    break;                }            }        }    }}

Consumer代码如下：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading;
namespace DemoSharp.EatApple{    /// <summary>    /// 消费者    /// </summary>    public class Consumer    {        private string name;
        public string Name        {            get { return name; }            set { name = value; }        }        private Dish dish;        private int timelong;
        public EventHandler GetAction;//声明一个事件，当放苹果时触发该事件
        public Consumer(string name, Dish dish, int timelong)        {            this.name = name;            this.dish = dish;            this.timelong = timelong;        }        public void run()        {            while (true)            {                bool flag=  dish.Get(name);                if (flag)                {                    //如果取到苹果，则调用事件，并开始吃                    if (GetAction != null)                    {                        GetAction(this, null);                    }                    try                    {                        Thread.Sleep(timelong);//吃苹果时间                    }                    catch (ThreadInterruptedException)                    {                    }                }                else {                    break;                }            }        }    }}

Dish代码如下：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading;
namespace DemoSharp.EatApple{    /// <summary>    /// 盘子，属于中间类    /// </summary>    public class Dish    {        private int f = 5;//表示盘子中还可以放几个苹果，最多只能放5个苹果
        private int EnabledNum;//可放苹果总数
        private int n = 0; //表示已经放了多少个苹果
        private object objGet = new object();
        private object objPut = new object();
        /// <summary>        /// 构造函数，初始化Dish对象        /// </summary>        /// <param name="num">表示削够多少个苹果结束</param>        public Dish(int num)        {            this.EnabledNum = num;        }        /// <summary>        /// 放苹果的方法        /// </summary>        /// <param name="name"></param>        ///<returns>是否放成功</returns>        public bool Put(string name)        {            lock (this)//同步控制放苹果            {                bool flag = false;
                while (f == 0)//苹果已满，线程等待                {                    try                    {                        System.Console.WriteLine(name + "正在等待放入苹果");                        Monitor.Wait(this);                    }                    catch (Exception ex)                    {                        System.Console.WriteLine(name + "等不及了");                    }                }                if (n < EnabledNum)                {                    f = f - 1;//削完一个苹果放一次                    n = n + 1;                    System.Console.WriteLine(name + "放1个苹果");                    flag = true;                }                Monitor.PulseAll(this);                return flag;            }        }
        /// <summary>        /// 取苹果的方法        /// </summary>        /// <param name="name"></param>        public bool Get(string name)        {            lock (this)//同步控制取苹果            {                bool flag = false;                while (f == 5)                {                    try                    {                        System.Console.WriteLine(name + "等待取苹果");                        Monitor.Wait(this);                    }                    catch (ThreadInterruptedException) { }                }                if (n <= EnabledNum)                {                    f = f + 1;                    System.Console.WriteLine(name + "取苹果吃...");                    flag = true;                }                Monitor.PulseAll(this);                return flag;            }
        }    }}

EatAppleSmp代码如下：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading;
namespace DemoSharp.EatApple{    public class EatAppleSmp    {        public EventHandler PutAction;//声明一个事件，当放苹果时触发该事件
        public EventHandler GetAction;//声明一个事件，当放苹果时触发该事件
        /// <summary>        /// 开始吃苹果        /// </summary>        public void BeginEat()        {            Thread th_mother, th_father, th_young, th_middle, th_old;//依次表示妈妈，爸爸，小弟，二弟，大哥            Dish dish = new Dish(30);            Productor mother = new Productor("Mama", dish);//建立线程            mother.PutAction += PutActionMethod;            Productor father = new Productor("Baba", dish);            father.PutAction += PutActionMethod;            Consumer old = new Consumer("Dage", dish, 1200);            old.GetAction += GetActionMethod;            Consumer middle = new Consumer("Erdi", dish, 1500);            middle.GetAction += GetActionMethod;            Consumer young = new Consumer("Sandi", dish, 1800);            young.GetAction += GetActionMethod;            th_mother = new Thread(new ThreadStart(mother.run));            th_mother.Name = "Mama";            th_father = new Thread(new ThreadStart(father.run));            th_father.Name = "Baba";            th_old = new Thread(new ThreadStart(old.run));            th_old.Name = "Dage";            th_middle = new Thread(new ThreadStart(middle.run));            th_middle.Name = "Erdi";            th_young = new Thread(new ThreadStart(young.run));            th_young.Name = "Sandi";            th_mother.Priority = ThreadPriority.Highest;//设置优先级            th_father.Priority = ThreadPriority.Normal;            th_old.Priority = ThreadPriority.Lowest;            th_middle.Priority = ThreadPriority.Normal;            th_young.Priority = ThreadPriority.Highest;            th_mother.Start();            th_father.Start();            th_old.Start();            th_middle.Start();            th_young.Start();        }
        private void GetActionMethod(object sender,EventArgs e)        {            if (GetAction != null)            {                GetAction(sender, e);            }        }
        private void PutActionMethod(object sender, EventArgs e)        {            if (PutAction != null)            {                PutAction(sender, e);            }        }    }}

界面类代码如下：

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 DemoSharp.EatApple;
namespace DemoSharp{    /// <summary>    /// 页面类    /// </summary>    public partial class EatAppleForm : Form    {        private EatAppleSmp m_EatAppleSmp = new EatAppleSmp();
        public EatAppleForm()        {            InitializeComponent();            InitView();            m_EatAppleSmp.PutAction += PutActionMethod;            m_EatAppleSmp.GetAction += GetActionMethod;        }
        /// <summary>        /// 初始化GroupBox        /// </summary>        private void InitView()        {            this.gbBaba.Controls.Clear();            this.gbMama.Controls.Clear();            this.gbDage.Controls.Clear();            this.gbErdi.Controls.Clear();            this.gbSandi.Controls.Clear();        }
        /// <summary>        /// 启动线程        /// </summary>        /// <param name="sender"></param>        /// <param name="e"></param>        private void btnStart_Click(object sender, EventArgs e)        {            this.m_EatAppleSmp.BeginEat();        }
        /// <summary>        /// 放苹果事件        /// </summary>        /// <param name="sender"></param>        /// <param name="e"></param>        private void PutActionMethod(object sender, EventArgs e)        {            Productor p = sender as Productor;            if (p != null)            {                if (p.Name == "Baba")                {                    AddItemToGroupBox(this.gbBaba, this.lblBaba);                }                if (p.Name == "Mama")                {                    AddItemToGroupBox(this.gbMama, this.lblMama);                }            }        }
        /// <summary>        /// 吃苹果事件        /// </summary>        /// <param name="sender"></param>        /// <param name="e"></param>        public void GetActionMethod(object sender, EventArgs e)        {            Consumer c = sender as Consumer;            if (c != null)            {                if (c.Name == "Dage")                {                    AddItemToGroupBox(this.gbDage, this.lblDage);                }                if (c.Name == "Erdi")                {                    AddItemToGroupBox(this.gbErdi, this.lblErdi);                }                if (c.Name == "Sandi")                {                    AddItemToGroupBox(this.gbSandi, this.lblSandi);                }            }        }
        /// <summary>        /// 往指定的GroupBox中添加对象        /// </summary>        /// <param name="gbView"></param>        /// <param name="lbl"></param>        private void AddItemToGroupBox(GroupBox gbView,Label lbl)        {            gbView.Invoke(new Action(() =>            {                PictureBox p = new PictureBox();                p.Width = 20;                p.Height = 20;                p.Dock = DockStyle.Left;                p.Image = this.imgLst01.Images[0];                p.Margin = new Padding(2);                gbView.Controls.Add(p);
            }));            //显示个数            lbl.Invoke(new Action(() => {                if (string.IsNullOrEmpty(lbl.Text))                {                    lbl.Text = "0";                }                lbl.Text = (int.Parse(lbl.Text) + 1).ToString();            }));        }    }}

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