我创建了一个小型电影租赁模拟程序。它是这样工作的： - 主线程让用户输入客户姓名
- 每个输入的客户都会启动一个新线程（Customer Runnable）
- 创建 5 个客户后，开始租赁服务（等待 5 个倒计时）
- 当客户运行（）时，他们将首先尝试从信号量中获取（）一个许可（有 5 个可用许可）
- 如果他们获得许可证，他们将等待 1-10 秒，然后租车，然后等待 1-3 秒，然后交付汽车
- 当汽车交付时，他们将重新开始循环迭代并尝试获得新的许可证
所以这似乎工作得很好；它适用于添加的前 5 个客户。5 号之后添加的客户似乎在 semaphore.aquire() 处等待，我不明白为什么，所以我在这里问。非常感谢所有帮助:)
应用程序.java：
import java.lang.System;import java.util.Scanner;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;
public class App {
public static CountDownLatch latch = new CountDownLatch(5);
public static Executor executor = Executors.newCachedThreadPool();
public static Store store = new Store();
public static Semaphore semaphore = new Semaphore(Store.getMovies().size());
Scanner in;
public App() {
in = new Scanner(System.in);
while (true) {
executor.execute(new Customer(in.nextLine()));
}
}
public static void main(String[] args) {
new App();
}
public CountDownLatch getLatch() {
return latch;
}
public Executor getExecutor() {
return executor;
}
public Semaphore getSemaphore() {
return semaphore;
}
}
客户.java：
public class Customer implements Runnable {
String name;
public Customer(String name) {
this.name = name;
}
public void run() {
try {
App.latch.countDown();
App.latch.await();
} catch (InterruptedException e) {
System.out.println(e.getMessage());
e.printStackTrace();
}
// Loop until ended
while (true) {
try {
if (App.semaphore.availablePermits() == 0)
System.out.println("No available movies");
// Acquire permit
App.semaphore.acquire();
// Sleep from 1-10 seconds before renting a Car
int rand = 1 + (int) (java.lang.Math.random() * 10);
Thread.sleep(rand * 1000);
App.store.rent(this);
// Sleep from 1-3 seconds before delivering the Car
rand = 1 + (int) (Math.random() * 3);
Thread.sleep(rand * 1000);
App.store.deliver(this);
} catch (InterruptedException e) {
e.printStackTrace();
} finally {
App.semaphore.release();
}
}
}
public String getName() {
return name;
}
}
存储.java：
import java.lang.String;import java.lang.System;import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class Store {
private static List<Movie> movies;
private static Lock lock = new ReentrantLock();
public Store() {
movies = new ArrayList<Movie>();
movies.add(new Movie("Godfather"));
movies.add(new Movie("LOTR"));
movies.add(new Movie("Schindlers list"));
movies.add(new Movie("Pulp fiction"));
movies.add(new Movie("Fight club"));
}
public void rent(Customer c) {
lock.lock();
for (Movie movie : movies) {
if (movie.getRentedBy() == null) {
movie.setRentedBy(c);
String str = c.getName() + " rented " + movie.getName();
System.out.printf("%-30s", str);
printStatus();
break;
}
}
lock.unlock();
}
// Deliver the Car
public void deliver(Customer c) {
lock.lock();
for (Movie movie : movies) {
if (movie.getRentedBy() != null && movie.getRentedBy().equals(c)) {
movie.setRentedBy(null);
String str = c.getName() + " delivered " + movie.getName();
System.out.printf("%-30s", str);
printStatus();
break;
}
}
lock.unlock();
}
public void printStatus() {
String str;
for (Movie m : movies) {
System.out.print(m.getName() + " - ");
if (m.getRentedBy() == null) {
str = "available";
} else {
str = "rented by " + m.getRentedBy().getName();
}
System.out.printf("%-15s", str);
}
System.out.println();
}
public static List<Movie> getMovies() {
return movies;
}
}
电影.java：
public class Movie {
private String name;
private Customer rentedBy;
public Movie(String name) {
this.name = name;
}
public String getName() {
return name;
}
public Customer getRentedBy() {
return rentedBy;
}
public void setRentedBy(Customer customer) {
this.rentedBy = customer;
}
}