package lock.reentrantlock2;
import java.util.concurrent.locks.*;/***账户类，需保持同步*/
public class Account
{//定义锁对象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{//账户余额大于取钱数目if (balance >= drawAmount){//吐出钞票System.out.println(Thread.currentThread().getName() + "取钱成功！吐出钞票:" + drawAmount);try{Thread.sleep(1);          }catch (InterruptedException ex){ex.printStackTrace();}//修改余额balance -= drawAmount;System.out.println("\t余额为: " + balance);}else{System.out.println(Thread.currentThread().getName() +"取钱失败！余额不足！");}          }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;/*** 调用account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(){account.draw(drawAmount);}
}

package lock.reentrantlock2;/***/
public class TestDraw
{public static void main(String[] args) {//创建一个账户Account acct = new Account("1234567" , 1000);//模拟两个线程对同一个账户取钱new DrawThread("甲" , acct , 800).start();new DrawThread("乙" , acct , 800).start();}
}