java实现磁盘调度算法（操作系统）

1.随机生成一个访问磁道顺序

import java.util.HashMap;
import java.util.Map;
import java.util.Random;

public class Course {
    private Map<Integer,Integer> map;
    int quantity;

    public int getQuantity() {
        return quantity;
    }

    public Course() {
        map=new HashMap<>();
        quantity=(new Random().nextInt(20))+1;//数量
        for (int i = 0; i < quantity; i++) {
            int n=new Random().nextInt(100);//磁道数
            if(map.containsValue(n)){
                i--;
            }else{
                map.put(i,n);
            }
        }
    }

    public Map<Integer, Integer> getMap() {
        return map;
    }
}

2.实现

import java.util.HashMap;
import java.util.Map;
import java.util.Random;
import java.util.Scanner;

public class Manage {
    private static int location;
    private static int choose=1;
    private static Map<Integer,Integer> map;
    private static int quantity;

    public static void main(String[] args) {
        location = new Random().nextInt(100);
        Course course = new Course();
        while (choose != 5) {
            map=new HashMap<>();
            for (Map.Entry<Integer,Integer> entry:course.getMap().entrySet()) {
                int key=entry.getKey();
                int value=entry.getValue();
                map.put(key,value);
            }
            System.out.println(map);
            System.out.println("磁盘调度算法选择");
            System.out.println("请选择内存分配策略：1.先来先服务算法 2.最短寻道时间优先算法 3.扫描算法 4.循环扫描算法 5.退出（请输入一个数字1~4）");
            Scanner scanner = new Scanner(System.in);
            choose = scanner.nextInt();
            int distance=0;
            int now_location=location;
            quantity=course.getQuantity();
            if(choose==1){
                for (int i = 0; i <quantity; i++) {
                    int value= map.get(i);
                    System.out.print("目前正在"+now_location+"道 ");
                    distance+=Math.abs(now_location-value);
                    now_location=value;
                }
                System.out.print("目前正在"+now_location+"道 ");
                System.out.println("\n"+"寻道长度为"+distance);
                map.clear();
            }else if(choose==2){
                for (int i = 0; i < quantity; i++) {
                    int min=200;
                    int key=0;
                    int value;
                    for (Map.Entry<Integer,Integer> entry:map.entrySet()) {
                        int x=Math.abs(entry.getValue()-now_location);
                        if(x<min){
                            min=x;
                            key=entry.getKey();
                        }
                    }
                    System.out.print("目前正在"+now_location+"道 ");
                    value= map.get(key);
                    distance+=Math.abs(now_location-value);
                    now_location=value;
                    map.remove(key);
                }
                System.out.print("目前正在"+now_location+"道 ");
                System.out.println("\n"+"寻道长度为"+distance);
            }else if(choose==3){
                int flag=0;//1为正数，2为负数
                for (int i = 0; i < quantity; i++) {
                    int min=200;
                    int key=-1;
                    int value;
                    int x;
                    int y;
                    for (Map.Entry<Integer,Integer> entry:map.entrySet()) {
                        x = entry.getValue() - now_location;
                        y = Math.abs(x);
                        if(flag==0) {
                            if (y < min) {
                                min = y;
                                key = entry.getKey();
                            }
                        }else if(flag==1&&x>0){
                            if (y < min) {
                                min = y;
                                key = entry.getKey();
                            }
                        }else if(flag==2&&x<0){
                            if (y < min) {
                                min = y;
                                key = entry.getKey();
                            }
                        }
                    }
                    if(key!=-1){
                    if((map.get(key)-now_location)>0){
                        flag=1;
                    }else {
                        flag=2;
                    }
                    }else{
                        flag=flag==1?2:1;
                        i--;
                        continue;
                    }
                    System.out.print("目前正在"+now_location+"道 ");
                    value= map.get(key);
                    distance+=Math.abs(now_location-value);
                    now_location=value;
                    map.remove(key);
                }
                System.out.print("目前正在"+now_location+"道 ");
                System.out.println("\n"+"寻道长度为"+distance);
            }else if(choose==4){
                //规定磁头道数单向由小到大移动
                for (int i = 0; i < quantity; i++) {
                    int min=200;
                    int key=-1;
                    int value;
                    int x;
                    int y;
                    for (Map.Entry<Integer,Integer> entry:map.entrySet()) {
                        x = entry.getValue() - now_location;
                        y = Math.abs(x);
                        if(x>0) {
                            if (y < min) {
                                min = y;
                                key = entry.getKey();
                            }
                        }
                    }
                    if(key==-1){
                        distance+=(99+99-now_location);
                        now_location=0;
                        i--;
                        continue;
                    }
                    System.out.print("目前正在"+now_location+"道 ");
                    value= map.get(key);
                    distance+=Math.abs(now_location-value);
                    now_location=value;
                    map.remove(key);
                }
                System.out.print("目前正在"+now_location+"道 ");
                System.out.println("\n"+"寻道长度为"+distance);
            }else{
                continue;
            }
        }
        System.out.println("退出");
    }
}