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.Threading.Tasks;

using System.Windows.Forms;

namespace WinLock

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        private void btn_Start_Click(object sender, EventArgs e)

        {

            listBox1.Items.Clear();

            Thread[] threads = new Thread[];//使用new关键字在堆里创建对象，其生命期相当于全局变量，但访问的时候与普通变量一样

            Account acc = new Account(, this);

            for (int i = ; i < ; i++)

            {

                Thread t = new Thread(acc.DoTransactions);

                t.Name = "线程" + i;

                threads[i] = t;

            }

            for (int i = ; i < ; i++)

            {

                threads[i].Start();

            }

        }

        delegate void AddListBoxItemDelegate(string str);//在类的内部也能声明代理

        public void AddListBoxItem(string str)

        {

            if (listBox1.InvokeRequired)//如果是跨线程访问控件则为true

            {

                AddListBoxItemDelegate d = AddListBoxItem;//代理

                listBox1.Invoke(d, str);//调用代理函数并传递参数

            }

            else

            {

                listBox1.Items.Add(str);//不是跨线程访问控件则直接访问该控件

            }

        }

    }

}

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading;

using System.Threading.Tasks;

namespace WinLock

{

    public class Account

    {

        private Object lockedObj = new Object();

        int balance;

        Random r = new Random();

        Form1 form1;

        public Account(int initial, Form1 form1)

        {

            this.form1 = form1;

            this.balance = initial;

        }

        /// <summary>

        /// 取款

        /// </summary>

        /// <param name="amount">取款金额</param>

        /// <returns>余额</returns>

        private int Withdraw(int amount)

        {

            if (balance < )

            {

                form1.AddListBoxItem("余额：" + balance + " 已经为负值了，还想取呵！");

            }

            //将lock (lockedObj)这句注释掉，看看会发生什么情况

            lock (lockedObj)

            {

                if (balance >= amount)

                {

                    string str = Thread.CurrentThread.Name + "取款---";

                    str += string.Format("取款前余额：{0,-6}取款：{1,-6}", balance, amount);

                    balance = balance - amount;

                    str += "取款后余额：" + balance;

                    form1.AddListBoxItem(str);

                    return amount;

                }

                else

                {

                    return ;

                }

            }

        }

        /// <summary>自动取款</summary>

        public void DoTransactions()//Transaction--事务

        {

            for (int i = ; i < ; i++)

            {

                Withdraw(r.Next(, ));

            }

        }

    }

}