Java多线程之银行出纳员仿真

package concurrent;

import java.util.LinkedList;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Random;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit; class Customer {
private final int serviceTime; public Customer(int tm) {
serviceTime = tm;
} public int getServiceTime() {
return serviceTime;
} public String toString() {
return "[" + serviceTime + "]";
}
} class CustomerLine extends ArrayBlockingQueue<Customer> {
public CustomerLine(int maxLineSize) {
super(maxLineSize);
} public String toString() {
if (this.size() == 0)
return "[Empty]"; StringBuilder result = new StringBuilder();
for (Customer customer : this) {
result.append(customer);
}
return result.toString();
}
} class CustomerGenerator implements Runnable {
private CustomerLine customers;
private static Random rand = new Random(47); public CustomerGenerator(CustomerLine cq) {
customers = cq;
} public void run() {
try {
while (!Thread.interrupted()) {
TimeUnit.MILLISECONDS.sleep(rand.nextInt(300));
customers.put(new Customer(rand.nextInt(1000)));
// System.out.println(customers.toString());
}
} catch (InterruptedException e) {
System.out.println("CustomerGenerator interrupted");
}
System.out.println("CustomerGenerator terminating");
}
} class Teller implements Runnable, Comparable<Teller> {
private static int counter = 0;
private final int id = counter++;
private int customersServed = 0;// 已经服务的客户
private CustomerLine customers;// 客户队列
private boolean servingCustomerLine = true;// 是否正在服务客户 public Teller(CustomerLine cq) {
customers = cq;
} @Override
public void run() {
try {
while (!Thread.interrupted()) {
Customer customer = customers.take();
TimeUnit.MILLISECONDS.sleep(customer.getServiceTime());
synchronized (this) {
customersServed++;
while (!servingCustomerLine)
wait();
}
}
} catch (InterruptedException e) {
System.out.println(this + " interrupted");
}
System.out.println(this + " terminating");// 结束
} public synchronized void doSomethingElse() {
customersServed = 0;
servingCustomerLine = false;
} public synchronized void serveCustomerLine() {
assert !servingCustomerLine : "already serving:" + this;
servingCustomerLine = true;
notifyAll();
} public String toString() {
return "Teller " + id + " ";
} public String shortString() {
return "T" + id;
} public synchronized int compareTo(Teller other) {
return customersServed < other.customersServed ? -1
: (customersServed == other.customersServed ? 0 : 1);
}
} class TellerManager implements Runnable {
private ExecutorService exec;
private CustomerLine customers;
private PriorityQueue<Teller> workingTellers = new PriorityQueue<Teller>();
private Queue<Teller> tellersDoingOtherThings = new LinkedList<Teller>();
private int adjustmentPeriod;
private static Random rand = new Random(47); public TellerManager(ExecutorService e, CustomerLine customers,
int adjustmentPeriod) {
exec = e;
this.customers = customers;
this.adjustmentPeriod = adjustmentPeriod;
Teller teller = new Teller(customers);
exec.execute(teller);
workingTellers.add(teller);
} /**
* 调整出纳员数量
* */
public void adjustTellerNumber() {
if (customers.size() / workingTellers.size() > 2) {
if (tellersDoingOtherThings.size() > 0) {
Teller teller = tellersDoingOtherThings.remove();
teller.serveCustomerLine();
workingTellers.offer(teller);
return;
}
Teller teller = new Teller(customers);
exec.execute(teller);
workingTellers.add(teller);
return;
}
if (workingTellers.size() > 1
&& customers.size() / workingTellers.size() < 2)
reassignOneTeller(); if (customers.size() == 0)
while (workingTellers.size() > 1)
reassignOneTeller();
} /**
* 分配一个出纳员
* */
private void reassignOneTeller() {
Teller teller = workingTellers.poll();
teller.doSomethingElse();
tellersDoingOtherThings.offer(teller);
} public void run() {
try {
while (!Thread.interrupted()) {
TimeUnit.MILLISECONDS.sleep(adjustmentPeriod);
adjustTellerNumber();
System.out.print(customers + "{");
for (Teller teller : workingTellers) {
System.out.print(teller.shortString() + " ");
}
System.out.println("}");
}
} catch (InterruptedException e) {
System.out.println(this + " interrupted");
}
System.out.println(this + " terminating");
} public String toString() {
return "TellerManager";
}
} public class BankTellerSimulation {
static final int MAX_LINE_SIZE = 50;
static final int ADJUSTMENT_PERIOD = 1000; public static void main(String[] args) throws Exception {
ExecutorService exec = Executors.newCachedThreadPool();
CustomerLine customers = new CustomerLine(MAX_LINE_SIZE);
exec.execute(new CustomerGenerator(customers));
exec.execute(new TellerManager(exec, customers, ADJUSTMENT_PERIOD));
if (args.length > 0)
TimeUnit.SECONDS.sleep(new Integer(args[0]));
else {
System.out.println("Press 'Enter' to quit");
System.in.read();
}
exec.shutdownNow();
}
}
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