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java線程學習6——線程同步之同步鎖
import java.util.concurrent.locks.ReentrantLock;
public class Account
{
/**
* 同步鎖
*/
private final ReentrantLock lock = new ReentrantLock();
/**
* 賬戶號
*/
private String accountNo;
/**
* 賬戶餘額
*/
private double balance;
public Account()
{
super();
}
public Account(String accountNo, double balance)
{
super();
this.accountNo = accountNo;
this.balance = balance;
}
@Override
public int hashCode()
{
return accountNo.hashCode();
}
@Override
public boolean equals(Object obj)
{
if (null != obj && obj.getClass() == Account.class)
{
Account target = (Account) obj;
return target.accountNo.equals(accountNo);
}
return false;
}
/**
* 同步方法，同步方法的監視器是this，同步方法可以將該類變為線程安全的類
* 任何時候隻有一個線程獲得對Account對象的鎖定，然後進入draw方法進行取錢
*/
public void draw(double drawAmount)
{
lock.lock();
try
{
if (balance >= drawAmount)
{
System.out.println(Thread.currentThread().getName() + "取出鈔票成功" + drawAmount);
balance -= drawAmount;
System.out.println("餘額為" + balance);
}
else
{
System.out.println("餘額不足");
}
}
finally
{
// 用finally塊保證釋放鎖
lock.unlock();
}
}
/* 隻提供Getters，不提供Setters，確保安全*/
public String getAccountNo()
{
return accountNo;
}
public double getBalance()
{
return balance;
}
}
public class DrawThread extends Thread
{
/**
* 模擬賬戶
*/
private Account ac;
/**
* 當前取錢線程希望取得的錢數
*/
private double drawAmount;
public DrawThread(String name, Account ac, double drawAmount)
{
super(name);
this.ac = ac;
this.drawAmount = drawAmount;
}
@Override
public void run()
{
ac.draw(drawAmount);
}
}
public class Test
{
public static void main(String[] args)
{
Account ac = new Account("00000001", 1000);
Thread t1 = new Thread(new DrawThread("Lily", ac, 800));
Thread t2 = new Thread(new DrawThread("Tom", ac, 800));
t1.start();
t2.start();
}
}
最後更新：2017-04-03 20:19:46