Question

作为多线程和服务器/客户端通信的练习，我正在模拟银行账户的操作。

以下代码一直有效，直到银行有足够的资金用于客户提出的请求。然后，例如，如果银行中有7美元并且客户（类Teller）要求10美元，则服务器以字符串响应：“线程＃无法获得这笔金额”，因为它应该是。问题是在打印出此消息后，我的服务器类将不会响应任何类型的后续请求：要么高于或低于银行拥有的金额。

public class BankServer {
public static void main(String[] args) {
    try {
        BankServer bankServer=new BankServer();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

public BankServer() throws IOException{
    account=new BankAccount();
    ss=new ServerSocket(PORT);
    while(!account.isEmpty()){
        Socket client=ss.accept();
        new Thread(new ConnectionHandler(client,account)).start();
        numberOfThreads++;
    }
}

private int numberOfThreads=0;
private BankAccount account;
private final static int PORT=8189;
private ServerSocket ss;}

存储资金的BankAccount类是这样构建的：

public class BankAccount {
public BankAccount(){
    amount=100;
}

public boolean getMoney(int qnt){
    lock.lock();
    if(qnt>amount){
        System.out.println(Thread.currentThread()+" could not get this amount of money: $"+qnt+".");
        return false; //the bank doesn't have enough money to satisfy the request
    }
    System.out.println(Thread.currentThread()+" got his money: $"+qnt+".");
    amount-=qnt;
    lock.unlock();
    return true;
}

public boolean isEmpty() {
    lock.lock();
    System.out.println("Money in the bank: "+amount+".");
    if(amount<=0){
        lock.unlock();
        return true;
    }
    lock.unlock();
    return false;
}

private int amount;
private ReentrantLock lock=new ReentrantLock();}

Ant这是ConnectionHandler，我用它来管理从用户到银行的每一个连接。

Answer 1

我不知道lock是什么，但你没有在if方法的第一个getMoney解锁它

public boolean getMoney(int qnt){
    lock.lock();
    if(qnt>amount){
        System.out.println(Thread.currentThread()+" could not get this amount of money: $"+qnt+".");

        //unlock here?

        return false; //the bank doesn't have enough money to satisfy the request
    }
    System.out.println(Thread.currentThread()+" got his money: $"+qnt+".");
    amount-=qnt;
    lock.unlock();
    return true;
}

服务器意外停止读取客户端消息

1 个答案: