TimeInterval

TimeInterval, 用于计算上次获取时间间隔的时间到当前时间的时间间隔

非线程安全版本，用于1个线程里。
public class TimeInterval {

    private long current;

    public TimeInterval() {
        current = System.currentTimeMillis();
    }

    public long get() {
        long last = current;
        current = System.currentTimeMillis();
        return current - last;
    }
}

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线程安全版本，可以用于多个线程并发。
import java.util.concurrent.atomic.AtomicLong;

    private final AtomicLong currentTimeHolder;

    public TimeInterval() {
        currentTimeHolder = new AtomicLong(System.currentTimeMillis());
    }

    public long get() {
        long current = System.currentTimeMillis();
        long last = currentTimeHolder.getAndSet(current);
        return current - last;
    }