小白抛砖引玉一下。
public class Solution {
    private long lastTime = System.currentTimeMillis();
    private int limitPerSecond;
    private int remains = limitPerSecond;

    public Solution(int permitsPerSecond) {
        this.limitPerSecond = permitsPerSecond;
    }

    public boolean acquire() {
        long curTime = System.currentTimeMillis();
        double timeEplaseInSec = (curTime - lastTime) / 1000.0;
        lastTime = curTime;
        remains += (int)(timeEplaseInSec * limitPerSecond);
        if (remains > limitPerSecond) {
            remains = limitPerSecond;
        }
        if (remains < 1) return false;
        else {
            remains -= 1;
            return true;
        }
    }

    public static void main(String[] args) {
        Solution limiter = new Solution(50);
        while (true) {
            if (limiter.acquire()) {
                // Do something
            } else {
                // wait...
            }
        }
    }
}