Java編程中實(shí)現(xiàn)Condition控制線程通信

package condition;
import java.util.concurrent.locks.*;
/**
 *存錢、取錢
 */
public class Account
{
 //顯示定義Lock對(duì)象
 private final Lock lock = new ReentrantLock();//可重入鎖
 //獲得指定Lock對(duì)象對(duì)應(yīng)的條件變量
 private final Condition cond = lock.newCondition(); //獲得condition實(shí)例
 private String accountNo;
 private double balance;
 //標(biāo)識(shí)賬戶中是否已經(jīng)存款的旗標(biāo)
 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)
 {
  //加鎖
  lock.lock();
  System.out.println(Thread.currentThread().getName() +"進(jìn)入封鎖區(qū)。。。。。。。。");
  try
  {
   //如果賬戶中還沒有存入存款，該線程等待
   if (!flag)
   {
    cond.await();
   }
   else
   {
    //執(zhí)行取錢操作
    System.out.println(Thread.currentThread().getName() +
     " 取錢:" + drawAmount);
    balance -= drawAmount;
    System.out.println("賬戶余額為：" + balance);
    //將標(biāo)識(shí)是否成功存入存款的旗標(biāo)設(shè)為false
    flag = false;
    //喚醒該Lock對(duì)象對(duì)應(yīng)的其他線程
    cond.signalAll();
   }
  }
  catch (InterruptedException ex)
  {
   ex.printStackTrace();
  }
  //使用finally塊來確保釋放鎖
  finally
  {
   lock.unlock();
   System.out.println("釋放了");
  }
 }
 /**
  * 存款
  * @param depositAmount
  */
 public void deposit(double depositAmount)
 {
  lock.lock();
  System.out.println(Thread.currentThread().getName() +"進(jìn)入封鎖區(qū)。。。。。。。。");
  try
  {
   //如果賬戶中已經(jīng)存入了存款，該線程等待
   if(flag)
   {
    System.out.println(Thread.currentThread().getName() +"等待。。。。。。");
    cond.await(); 
   }
   else
   {
    //執(zhí)行存款操作
    System.out.println(Thread.currentThread().getName() +
     " 存款:" + depositAmount);
    balance += depositAmount;
    System.out.println("賬戶余額為：" + balance);
    //將標(biāo)識(shí)是否成功存入存款的旗標(biāo)設(shè)為true
    flag = true;
    //喚醒該Lock對(duì)象對(duì)應(yīng)的其他線程
    cond.signalAll();
   }
  }
  catch (InterruptedException ex)
  {
   ex.printStackTrace();
  }
  //使用finally塊來確保釋放鎖
  finally
  {
   lock.unlock();
   System.out.println(Thread.currentThread().getName() +"釋放鎖。。。。");
  }
 }
 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)安全問題。
 public void run()
 {
  for (int i = 0 ; i < 6 ; i++ )
  {
   account.draw(drawAmount);
  }
 }
}

package condition;
/**
 *存錢
 */
public class DepositThread 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 depositAmount;
 public DepositThread(String name , Account account ,
  double depositAmount)
 {
  super(name);
  this.account = account;
  this.depositAmount = depositAmount;
 }
 //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)安全問題。
 public void run()
 {
  for (int i = 0 ; i < 2 ; i++ )
  {
   account.deposit(depositAmount);
   System.out.println(Thread.currentThread().getName()+" 存錢結(jié)束！");
  }  
 }
}

package condition;
public class TestDraw
{
 public static void main(String[] args)
 {
  //創(chuàng)建一個(gè)賬戶
  Account acct = new Account("1234567" , 0);
  new DrawThread("取錢者" , acct , 800).start();
  new DepositThread("存錢者甲" , acct , 800).start();
  new DepositThread("存錢者乙" , acct , 800).start();
  new DepositThread("存錢者丙" , acct , 800).start();
 }
}