磁盘调度算法java

磁盘调度算法是操作系统中的一个重要概念，它是指操作系统对于磁盘上的数据进行访问时，按照一定的规则来安排磁盘的读写顺序，以提高磁盘的访问效率。下面是两种常见的磁盘调度算法的Java实现：

1.先来看最短时间优先算法(SSTF)的Java实现：

public class SSTF {
    public static void main(String[] args) {
        int[] queue = {55, 58, 39, 18, 90, 160, 150, 38, 184};
        int head = 50;
        int sum = 0;
        int[] flag = new int[queue.length];
        for (int i = 0; i < queue.length; i++) {
            int min = Integer.MAX_VALUE;
            int index = 0;
            for (int j = 0; j < queue.length; j++) {
                if (flag[j] == 0) {
                    int distance = Math.abs(queue[j] - head);
                    if (distance < min) {
                        min = distance;
                        index = j;
                    }
                }
            }
            flag[index] = 1;
            sum += min;
            head = queue[index];
        }
        System.out.println("SSTF算法磁盘移动的总磁道数为：" + sum);
    }
}

2.再来看扫描算法(SCAN)的Java实现：

public class SCAN {
    public static void main(String[] args) {
        int[] queue = {55, 58, 39, 18, 90, 160, 150, 38, 184};
        int head = 50;
        int sum = 0;
        int direction = 1; // 1表示向右，-1表示向左
        Arrays.sort(queue);
        int index = Arrays.binarySearch(queue, head);
        if (index < 0) {
            index = -index - 1;
        }
        while (true) {
            if (direction == 1) {
                for (int i = index; i < queue.length; i++) {
                    sum += Math.abs(queue[i] - head);
                    head = queue[i];
                }
                direction = -1;
                index--;
            } else {
                for (int i = index; i >= 0; i--) {
                    sum += Math.abs(queue[i] - head);
                    head = queue[i];
                }
                direction = 1;
                index++;
            }
            if (index < 0 || index == queue.length) {
                break;
            }
        }
        System.out.println("SCAN算法磁盘移动的总磁道数为：" + sum);
    }
}