并发编程案例：Java多线程银行转账系统

原创待我称王封你为后i 2024-10-31 18:54 9阅读 0赞

并发编程是编程中的一个重要领域，特别是在涉及到多线程操作时，比如银行转账系统。在Java中，多线程可以通过实现`Runnable`接口或者继承`Thread`类来创建。下面是一个简单的Java多线程银行转账系统的示例代码，它展示了如何使用`synchronized`关键字来确保线程安全。

```javaclass BankAccount {
 private double balance;

public BankAccount(double balance) {
 this.balance = balance;
 }

//存款方法 public synchronized void deposit(double amount) {
 double newBalance = balance + amount;
 balance = newBalance;
 }

//取款方法 public synchronized boolean withdraw(double amount) {
if (balance >= amount) {
 double newBalance = balance - amount;
 balance = newBalance;
 return true;
 }
 return false;
 }

// 获取账户余额 public synchronized double getBalance() {
 return balance;
 }
}

class TransferThread extends Thread {
 private BankAccount fromAccount;
 private BankAccount toAccount;
 private double amount;

public TransferThread(BankAccount fromAccount, BankAccount toAccount, double amount) {
 this.fromAccount = fromAccount;
 this.toAccount = toAccount;
 this.amount = amount;
 }

@Override public void run() {
 synchronized (fromAccount) {
 synchronized (toAccount) {
if (fromAccount.withdraw(amount)) {
 toAccount.deposit(amount);
 System.out.println("Transfer successful. From: " + fromAccount.getBalance() + ", To: " + toAccount.getBalance());
} else {
 System.out.println("Transfer failed. Insufficient funds.");
 }
 }
 }
 }
}

public class BankTransferSystem {
 public static void main(String[] args) {
 BankAccount account1 = new BankAccount(1000);
 BankAccount account2 = new BankAccount(500);

TransferThread transfer1 = new TransferThread(account1, account2,200);
TransferThread transfer2 = new TransferThread(account2, account1,300);

transfer1.start();
 transfer2.start();
 }
}
```在这个例子中，`BankAccount`类有两个`synchronized`方法：`deposit`和`withdraw`，它们确保了在任何时候只有一个线程可以修改账户余额。`TransferThread`类继承自`Thread`类，并在其`run`方法中执行转账操作。为了确保转账操作的原子性，我们使用了双重同步锁，即在`fromAccount`和`toAccount`上都加锁。

请注意，这个例子是一个简化的模型，实际的银行转账系统会更加复杂，需要处理更多的并发问题和安全问题，比如使用数据库事务、乐观锁、悲观锁等技术来确保数据的一致性和完整性。此外，还需要考虑性能优化，比如减少锁的粒度，使用并发集合等。