package lock.reentrantlock2;
import java.util.concurrent.locks.*;
/**
 *賬戶類，需保持同步
 */
public class Account
{
  //定義鎖對(duì)象
  private final ReentrantLock lock = new ReentrantLock();
  private String accountNo;
  private double balance;
  public Account(){}
  public Account(String accountNo , double balance)
  {
    this.accountNo = accountNo;
    this.balance = balance;
  }
  public void setAccountNo(String accountNo)
  {
    this.accountNo = accountNo;
  }
  public String getAccountNo()
  {
     return this.accountNo;
  }
  public double getBalance()
  {
     return this.balance;
  }
  public void draw(double drawAmount)
  {
    lock.lock();
    try
    {
      //賬戶余額大于取錢數(shù)目
      if (balance >= drawAmount)
      {
        //吐出鈔票
        System.out.println(Thread.currentThread().getName() +
          "取錢成功！吐出鈔票:" + drawAmount);
        try
        {
          Thread.sleep(1);      
        }
        catch (InterruptedException ex)
        {
          ex.printStackTrace();
        }
        //修改余額
        balance -= drawAmount;
        System.out.println("\t余額為: " + balance);
      }
      else
      {
        System.out.println(Thread.currentThread().getName() +
          "取錢失??！余額不足！");
      }     
    }
    finally
    {
      lock.unlock();
    }
  }
  public int hashCode()
  {
    return accountNo.hashCode();
  }
  public boolean equals(Object obj)
  {
    if (obj != null && obj.getClass() == Account.class)
    {
      Account target = (Account)obj;
      return target.getAccountNo().equals(accountNo);
    }
    return false;
  }
}

package lock.reentrantlock2;
/**
 * 調(diào)用account取錢
 *
 */
public class DrawThread extends Thread
{
  //模擬用戶賬戶
  private Account account;
  //當(dāng)前取錢線程所希望取的錢數(shù)
  private double drawAmount;
  public DrawThread(String name , Account account ,
    double drawAmount)
  {
    super(name);
    this.account = account;
    this.drawAmount = drawAmount;
  }
  //當(dāng)多條線程修改同一個(gè)共享數(shù)據(jù)時(shí)，將涉及到數(shù)據(jù)安全問(wèn)題。
  public void run()
  {
    account.draw(drawAmount);
  }
}

package lock.reentrantlock2;
/**
 */
public class TestDraw
{
  public static void main(String[] args)
  {
    //創(chuàng)建一個(gè)賬戶
    Account acct = new Account("1234567" , 1000);
    //模擬兩個(gè)線程對(duì)同一個(gè)賬戶取錢
    new DrawThread("甲" , acct , 800).start();
    new DrawThread("乙" , acct , 800).start();
  }
}