[数据结构与算法]操作系统：磁盘调度算法（JAVA)

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	import java.util.Arrays;
	import java.util.Scanner;
	
	import org.omg.Messaging.SYNC_WITH_TRANSPORT;
	
	public class DiskSchedulingAlgorithm {
		
		private static Scanner in;
		public static void main(String[] args) {
			in = new Scanner(System.in);
			System.out.println("请输入磁盘柱头起始位置：");
			int start =  in.nextInt();
			System.out.println("输入请求队列的个数：");
			int num = in.nextInt();
			int[] S = new int[num];  
			System.out.println("请输入各请求的磁道位置：");
			for(int i = 0;i<num;i++){
				S[i] = in.nextInt();
			}
			boolean T = true;
			int C;
			int choose ;
			while(T==true){
			System.out.println("请选择对应的磁盘调度:"+" "+"1.FCFS 2.SSTF 3.SCAN");
			 choose =in.nextInt();
			switch(choose){
			case 1:
				FCFS(S,start,num); 
				break;
			case 2:
				SSTF(S,start,num);
				break;
			case 3:
				SCAN(S,start,num);
				break;
			}
			System.out.println(" ");
			System.out.println("是否继续: 1/2");
			C = in.nextInt();
			T = false;
			if(C==1){
				T = true;
			}
			else{
				System.out.printf("您已退出！");
			}
		  }
		}
		public static void FCFS(int S[],int start,int num){
			int result = 0;
			System.out.print("采用FCFS算法调度时，磁头移动顺序为：");
			System.out.print(start);
			for(int i = 0;i<num-1;i++){
				System.out.print("->"+S[i]);
				result += Math.abs(S[i+1]-S[i]);
			}
			double avarage = 1.0*result/num;
			System.out.println(" ");
			System.out.print("磁头移动总量为："+result+" "+"磁盘的平均移动量为："+String.format("%.2f",avarage));
		}
		public static void SSTF(int S[],int start,int num){
			int[] T = new int[num];
			for(int i = 0;i<num;i++){
				T[i]=S[i];
			}
			int sum = 0;
			int key=num;
			System.out.print("采用SSTF算法调度时，磁头移动顺序为：");
			System.out.print(start);
			while(num>=1){
			int[] DISTANCE = new int[num];
			
			for(int i = 0;i<num;i++){
					DISTANCE[i] = Math.abs(start-T[i]);   //存入各磁道和磁头的距离
			}
			int min = DISTANCE[0];
			int corners= 0;
			for(int i = 1;i<num;i++){
				if(min>DISTANCE[i]){
				   min = DISTANCE[i];
				   corners = i;
				}
			}
			System.out.print("->"+S[corners]); 
			start =  T[corners];    //输入距离最短的值
			sum +=DISTANCE[corners];
			num --;
			int k=0;
			for(int i = 0;i<=num;i++){
				if(T[i]!=T[corners]){
					T[k] = T[i];
					k++;
				}
			}
		}
		    System.out.println(" ");
			System.out.println("磁头移动量为："+sum+" "+"平均磁头移动量为："+(double)(sum*1.0/key));
		}
		public static void SCAN(int S[],int start,int num){
			Arrays.sort(S);
			int key =num;
			System.out.println("请选择第一个要访问的磁道号：");
			int First = in.nextInt();
			int corners = 0;
			System.out.print(start);
			int sum = Math.abs(start-First);
			for(int i = 0;i<num;i++){
				if(S[i]==First){
					corners = i;
				}
			}
			if(start>First){  
				for(int i = corners;i>=0;i--){
					System.out.print("->"+S[i]);
				}
				for(int i = corners+1;i<num;i++){
					System.out.print("->"+S[i]);
				}
				for(int i = corners;i>0;i--){
					sum+=Math.abs(S[i]-S[i-1]);
				}
				sum +=Math.abs(S[0]-S[corners+1]);
				for(int i = corners+2;i<num;i++){
					sum+=Math.abs(S[i]-S[i-1]);
				}
				double average = sum*1.0/key;
				System.out.println(" ");
				System.out.println("采用SCAN算法调度时，磁头移动顺序为：");
				System.out.println("磁头移动量为："+sum+" "+"平均磁头移动量为："+String.format("%.2f", average));
			}	
			else{
				for(int i = corners;i<num;i++){
					System.out.print("->"+S[i]);
				}
				for(int i = corners-1;i>=0;i--){
					System.out.print("->"+S[i]);
				}
				for(int i = corners+1;i<num;i++){
					sum+=Math.abs(S[i]-S[i-1]);
				}
				sum +=Math.abs(S[num-1]-S[corners-1]);
				for(int i = corners-1;i>0;i--){
					sum+=Math.abs(S[i]-S[i-1]);
				}
				double average = sum*1.0/key;
				System.out.println(" ");
				System.out.println("采用SCAN算法调度时，磁头移动顺序为：");
				System.out.println("磁头移动量为："+sum+" "+"平均磁头移动量为："+String.format("%.2f", average));
			}
		}
	}

运行效果：

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