Java令牌桶简单实现

令牌桶简单实现代码

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;


public class TokenLimiter {
    
    public static final String TOKEN = "lp";

    
    private ArrayBlockingQueue blockingQueue;
    
    private int limit;
    
    private int period;
    
    private int amount;


    public TokenLimiter(int limit, int period, int amount) {
        this.limit = limit;
        this.period = period;
        this.amount = amount;
        blockingQueue = new ArrayBlockingQueue<>(limit);
        init();
    }

    
    public void start(Object lock) {
        Executors.newScheduledThreadPool(1).scheduleAtFixedRate(() -> {
            synchronized (lock) {
                addToken();
                lock.notifyAll();
            }
        }, 500, this.period, TimeUnit.MILLISECONDS);
    }

    
    public boolean tryAcquire() {
        // 队首元素出队
        return blockingQueue.poll() != null;
    }

    
    private void init() {
        for (int i = 0; i < limit; i++) {
            blockingQueue.add(TOKEN);
        }
    }

    
    private void addToken() {
        for (int i = 0; i < this.amount; i++) {
            // 溢出返回false
            blockingQueue.offer(TOKEN);
        }
    }

}

测试代码:

public class TestTokenLimiter {
    final static Object LOCK = new Object();

    
    public static void main(String[] args) throws InterruptedException {
        int period = 500;
        TokenLimiter limiter = new TokenLimiter(2, period, 2);

        limiter.start(LOCK);

        // 让线程先产生2个令牌
        synchronized (LOCK) {
            LOCK.wait();
        }

        for (int i = 0; i < 4; i++) {
            new Thread(() -> {
                while (true) {
                    String name = Thread.currentThread().getName();
                    if (limiter.tryAcquire()) {
                        System.out.println(name + ":拿到令牌");
                    } else {
                        System.out.println(name + ":没有令牌");
                    }
                    try {
                        Thread.sleep(period);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }).start();
        }

    }

}