Java编程中实现Condition控制线程通信

package condition;
import java.util.concurrent.locks.*;
/**
 *存钱、取钱
 */
public class Account
{
 //显示定义Lock对象
 private final Lock lock = new ReentrantLock();//可重入锁
 //获得指定Lock对象对应的条件变量
 private final Condition cond = lock.newCondition(); //获得condition实例
 private String accountNo;
 private double balance;
 //标识账户中是否已经存款的旗标
 private boolean flag = false;
 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;
 }
 /**
  *取款
  * @param drawAmount
  */
 public void draw(double drawAmount)
 {
  //加锁
  lock.lock();
  System.out.println(Thread.currentThread().getName() +"进入封锁区。。。。。。。。");
  try
  {
   //如果账户中还没有存入存款，该线程等待
   if (!flag)
   {
    cond.await();
   }
   else
   {
    //执行取钱操作
    System.out.println(Thread.currentThread().getName() +
     " 取钱:" + drawAmount);
    balance -= drawAmount;
    System.out.println("账户余额为：" + balance);
    //将标识是否成功存入存款的旗标设为false
    flag = false;
    //唤醒该Lock对象对应的其他线程
    cond.signalAll();
   }
  }
  catch (InterruptedException ex)
  {
   ex.printStackTrace();
  }
  //使用finally块来确保释放锁
  finally
  {
   lock.unlock();
   System.out.println("释放了");
  }
 }
 /**
  * 存款
  * @param depositAmount
  */
 public void deposit(double depositAmount)
 {
  lock.lock();
  System.out.println(Thread.currentThread().getName() +"进入封锁区。。。。。。。。");
  try
  {
   //如果账户中已经存入了存款，该线程等待
   if(flag)
   {
    System.out.println(Thread.currentThread().getName() +"等待。。。。。。");
    cond.await(); 
   }
   else
   {
    //执行存款操作
    System.out.println(Thread.currentThread().getName() +
     " 存款:" + depositAmount);
    balance += depositAmount;
    System.out.println("账户余额为：" + balance);
    //将标识是否成功存入存款的旗标设为true
    flag = true;
    //唤醒该Lock对象对应的其他线程
    cond.signalAll();
   }
  }
  catch (InterruptedException ex)
  {
   ex.printStackTrace();
  }
  //使用finally块来确保释放锁
  finally
  {
   lock.unlock();
   System.out.println(Thread.currentThread().getName() +"释放锁。。。。");
  }
 }
 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 condition;
/**
 *取钱
 */
public class DrawThread extends Thread
{
 //模拟用户账户
 private Account account;
 //当前取钱线程所希望取的钱数
 private double drawAmount;
 public DrawThread(String name , Account account ,
  double drawAmount)
 {
  super(name);
  this.account = account;
  this.drawAmount = drawAmount;
 }
 //当多条线程修改同一个共享数据时，将涉及到数据安全问题。
 public void run()
 {
  for (int i = 0 ; i < 6 ; i++ )
  {
   account.draw(drawAmount);
  }
 }
}

package condition;
/**
 *存钱
 */
public class DepositThread extends Thread
{
 //模拟用户账户
 private Account account;
 //当前取钱线程所希望取的钱数
 private double depositAmount;
 public DepositThread(String name , Account account ,
  double depositAmount)
 {
  super(name);
  this.account = account;
  this.depositAmount = depositAmount;
 }
 //当多条线程修改同一个共享数据时，将涉及到数据安全问题。
 public void run()
 {
  for (int i = 0 ; i < 2 ; i++ )
  {
   account.deposit(depositAmount);
   System.out.println(Thread.currentThread().getName()+" 存钱结束！");
  }  
 }
}

package condition;
public class TestDraw
{
 public static void main(String[] args)
 {
  //创建一个账户
  Account acct = new Account("1234567" , 0);
  new DrawThread("取钱者" , acct , 800).start();
  new DepositThread("存钱者甲" , acct , 800).start();
  new DepositThread("存钱者乙" , acct , 800).start();
  new DepositThread("存钱者丙" , acct , 800).start();
 }
}