import java.util.ArrayList; import java.util.List; public class Practice1 { public static void main(String[] args) { List<Process> processes = new ArrayList<>(); processes.add(new Process(1, 0, 5)); processes.add(new Process(2, 1, 3)); processes.add(new Process(3, 2, 8)); processes.add(new Process(4, 3, 6)); processes.add(new Process(5, 4, 2)); Scheduler scheduler = new Scheduler(processes); scheduler.fcfs();//先来先服务 scheduler.sjf();//最短作业优先 scheduler.hrrn();//最高响应比优先 } } class Process {//定义进程类，用于存储进程的相关信息 int pName;//进程名字 int arrivalTime;//进程到达时间 int executeTime;//进程执行时间 public Process(int pName, int arrivalTime, int executeTime) { this.pName = pName; this.arrivalTime = arrivalTime; this.executeTime = executeTime; } } class Scheduler {//调度器类，用于实现不同的调度算法 List<Process> processes;//所有进程 List<Process> readyQueue;//就绪队列 List<Process> finishedProcesses;//已完成的进程 public Scheduler(List<Process> processes) { this.processes = processes; this.readyQueue = new ArrayList<>(); this.finishedProcesses = new ArrayList<>(); } public void fcfs() {//先来先服务 int currentTime = 0; while (!readyQueue.isEmpty() || !processes.isEmpty()) { //将到达时间小于等于当前时间的进程加入就绪队列 while (!processes.isEmpty() && processes.get(0).arrivalTime <= currentTime) { readyQueue.add(processes.remove(0)); } if (readyQueue.isEmpty()) { currentTime++;//如果没有进程在执行，时间+1 } else { Process process = readyQueue.get(0);//执行队首进程 process.executeTime--; currentTime++; process = readyQueue.remove(0); if (process.executeTime == 0) { //进程完成 processFinish(process, currentTime); } } } } pu

blic void sjf() {//最短作业优先 int currentTime = 0; while (!readyQueue.isEmpty() || !processes.isEmpty()) { //将到达时间小于等于当前时间的进程加入就绪队列 while (!processes.isEmpty() && processes.get(0).arrivalTime <= currentTime) { readyQueue.add(processes.remove(0)); } if (readyQueue.isEmpty()) { currentTime++;//如果没有进程在执行，时间+1 } else { //找到执行时间最短的进程，并执行 Process shortestProcess = readyQueue.get(0); for (int i = 1; i < readyQueue.size(); i++) { if (readyQueue.get(i).executeTime < shortestProcess.executeTime) { shortestProcess = readyQueue.get(i); } } shortestProcess.executeTime--; currentTime++; if (shortestProcess.executeTime == 0) { //进程完成 processFinish(shortestProcess, currentTime); } } } } public void hrrn() {//最高响应比优先 int currentTime = 0; while (!readyQueue.isEmpty() || !processes.isEmpty()) { //将到达时间小于等于当前时间的进程加入就绪队列 while (!processes.isEmpty() && processes.get(0).arrivalTime <= currentTime) { readyQueue.add(processes.remove(0)); } if (readyQueue.isEmpty()) { currentTime++;//如果没有进程在执行，时间+1 } else { //计算每个进程的响应比，并找到响应比最高的进程执行 Process highestRatioProcess = readyQueue.get(0); double highestRatio = (double) (highestRatioProcess.executeTime + currentTime - highestRatioProcess.arrivalTime) / highestRatioProcess.executeTime; for (int i = 1; i < readyQueue.size(); i++) { Process process = readyQueue.get(i); double ratio = (double) (process.executeTime + currentTime - process.arrivalTime) / process.executeTime; if (ratio > highestRatio) { highestRatioProcess = process; highestRatio = ratio; } } highestRatioProcess.executeTime--; currentTime++; if (highestRatioProcess.executeTime == 0) { //进程完成 processFinish(highestRatioProcess, currentTime); } } } } private void processFinish(Process process, int finishTime) { process.executeTime = finishTime - process.arrivalTime;//计算进程响应时间 finishedProcesses.add(process); } }