浅谈java安全编码指南之死锁dead lock

public class DiffLockOrder {

    private int amount;

    public DiffLockOrder(int amount){
       this.amount=amount;
    }

    public void transfer(DiffLockOrder target,int transferAmount){
        synchronized (this){
            synchronized (target){
                if(amount< transferAmount){
                    System.out.println("余额不足！");
                }else{
                    amount=amount-transferAmount;
                    target.amount=target.amount+transferAmount;
                }
            }
        }
    }
}

DiffLockOrder account1 = new DiffLockOrder(1000);
DiffLockOrder account2 = new DiffLockOrder(500);

Runnable target1= ()->account1.transfer(account2,200);
Runnable target2= ()->account2.transfer(account1,100);
new Thread(target1).start();
new Thread(target2).start();

public class LockWithPrivateStatic {

    private int amount;

    private static final Object lock = new Object();

    public LockWithPrivateStatic(int amount){
       this.amount=amount;
    }

    public void transfer(LockWithPrivateStatic target, int transferAmount){
        synchronized (lock) {
            if (amount < transferAmount) {
                System.out.println("余额不足！");
            } else {
                amount = amount - transferAmount;
                target.amount = target.amount + transferAmount;
            }
        }
    }
}

private final long id; // 唯一ID，用来排序
private static final AtomicLong nextID = new AtomicLong(0); // 用来生成ID

public DiffLockWithOrder(int amount){
    this.amount=amount;
    this.id = nextID.getAndIncrement();
}

public void transfer(DiffLockWithOrder target, int transferAmount){
    DiffLockWithOrder fist, second;

    if (compareTo(target) < 0) {
        fist = this;
        second = target;
    } else {
        fist = target;
        second = this;
    }

    synchronized (fist){
        synchronized (second){
            if(amount< transferAmount){
                System.out.println("余额不足！");
            }else{
                amount=amount-transferAmount;
                target.amount=target.amount+transferAmount;
            }
        }
    }
}

public class DiffLockWithReentrantLock {

    private int amount;
    private final Lock lock = new ReentrantLock();

    public DiffLockWithReentrantLock(int amount){
        this.amount=amount;
    }

    private void transfer(DiffLockWithReentrantLock target, int transferAmount)
            throws InterruptedException {
        while (true) {
            if (this.lock.tryLock()) {
                try {
                    if (target.lock.tryLock()) {
                        try {
                            if(amount< transferAmount){
                                System.out.println("余额不足！");
                            }else{
                                amount=amount-transferAmount;
                                target.amount=target.amount+transferAmount;
                            }
                            break;
                        } finally {
                            target.lock.unlock();
                        }
                    }
                } finally {
                    this.lock.unlock();
                }
            }
            //随机sleep一定的时间，保证可以释放掉锁
            Thread.sleep(1000+new Random(1000L).nextInt(1000));
        }
    }

}