问在java中实现事务，而不使用任何库(如@ transaction )

EN

private void transfer(fromAccount,toAccount, amount){ 
    boolean withdrawn = false;
    try {
        fromAccount.withdraw(amount);
        withdrawn = true;
        toAccount.deposit(amount); 
    } catch(Exception e) {
        if(withdrawn)
            fromAccount.deposit(amount);
        // you can throw another Exception here, otherwise you just fail silently
    }
}

public class YourClass() { 

   private void transfer(fromAccount,toAccount, amount) {
       Account fromAccountObj = new Account(fromAccount);
       Account toAccountObj = new Account(toAccount);
       synchronized(fromAccountObj) { 
          fromAccount.withdraw(amount);
       }
       synchronized(toAccountObj) { 
          toAccount.deposit(amount);
       }
   }
}

public class Account {
   private String accountNumber;
   public Account(String accountNumber) {
       this.accountNumber = accountNumber;
   }

   @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Account account = (Account) o;
        return accountNumber.equals(account.accountNumber);
    }

    @Override
    public int hashCode() {
        return Objects.hash(accountNumber);
    }
}