（操作系统实验）结合PCB模拟进程就绪、运行、等待三种状态切换的实验

算法设计

编程环境

Java8+Windows10+记事本

代码文件架构

详细代码

PCB.java

public class PCB{

	private String pid;//进程号
	private String state;//进程状态：就绪，运行，等待，待创建
	
	public void setPid(String pid){this.pid = pid;}
	public String getPid(){return this.pid;}

	public void setState(String state){this.state = state;}
	public String getState(){return this.state;}
}

ProcessState.java

import java.util.*;
import java.io.*;

public class ProcessState{
	
	private ArrayList<PCB> pcbList = new ArrayList<>();
	
	public static void main(String[] args){
		ProcessState ps = new ProcessState();
		ps.readPCB();
		
		ps.run();
	}
	
	//从文件in.txt读入pcb，放入pcb池子中
	public void readPCB(){
		try{
			FileReader fr = new FileReader("in.txt");
			BufferedReader br = new BufferedReader(fr);
				
			String line = null;
			while((line = br.readLine()) != null){
				String[] tmp = line.split(" ");
				PCB pcb = new PCB();
				pcb.setPid(tmp[0]);
				pcb.setState(tmp[1]);

				pcbList.add(pcb);	
			}
			
			br.close();
			fr.close();

		}catch(IOException e){
			e.printStackTrace();
		}
		
	}
	

	//通过PCB队列的组织管理来模拟进程就绪、运行、等待等状态之间的切换
	public void run(){
		//当前格局
		printCurrentState();

		Scanner scan = new Scanner(System.in);
		String choice = null;
		while(true){
			menu();
			System.out.print("请输入您的选择：");
			choice = scan.next();
			switch(choice){
				case "0":
					System.out.println("您已经退出了模拟实验，欢迎再来！");
					System.exit(0);
				case "1":
					createProcess();
					break;
				case "2":
					destroyProcess();
					break;
				case "3":
					hangUpProcess();
					break;
				case "4":
					activateProcess();
					break;
				case "5":
					timeUp();
					break;
				default:
					System.out.println("您输入错误，请重新输入！");
					break;
					
			}
			
			runProcess();//不管怎么选择，总得有个进程运行吧！
				
			//打印当前格局
			printCurrentState();

		}
	}

	//与用户交互菜单
	public void menu(){
		System.out.println("*************欢迎来模拟实验**************");
		System.out.println("1>>>>>>>>>>>>>>>>>>>创建进程");
		System.out.println("2>>>>>>>>>>>>>>>>>>>销毁进程");
		System.out.println("3>>>>>>>>>>>>>>>>>>>挂起进程");
		System.out.println("4>>>>>>>>>>>>>>>>>>>激活进程");
		System.out.println("5>>>>>>>>>>>>>>>>>>>时间片到");
		System.out.println("0>>>>>>>>>>>>>>>>>>>退出");
	}

	//打印当前格局
	public void printCurrentState(){
	
		System.out.println("----------------------------------------------");
		System.out.println("进程号	进程状态");
		System.out.println("----------------------------------------------");
		for(int i = 0; i < pcbList.size(); i++){
			System.out.println(pcbList.get(i).getPid()+"	"+pcbList.get(i).getState());
		}
		System.out.println("----------------------------------------------");
		System.out.println();
	}

	//运行进程
	public void runProcess(){
		//先判断有没有进程在运行
		boolean flag = false;
		for(int i = 0; i < pcbList.size(); i++){
			if(pcbList.get(i).getState().equals("运行")){
				flag = true;
				break;
			}
		}
		//如果当前没有进程在运行，就随便选一个进程运行（这是为了简化进程调度）
		if(flag == false){
			for(int i = 0; i < pcbList.size(); i++){
				if(pcbList.get(i).getState().equals("就绪")){
					pcbList.get(i).setState("运行");
					break;
				}
			}
		}
	}

	//创建进程
	public void createProcess(){

		for(int i = 0; i < pcbList.size(); i++){
			if(pcbList.get(i).getState().equals("待创建")){
				pcbList.get(i).setState("就绪");
				System.out.println("您创建的进程是"+pcbList.get(i).getPid());
				break;
			}
		}
	}

	//销毁进程
	public void destroyProcess(){
		for(int i = 0; i < pcbList.size(); i++){
			if(pcbList.get(i).getState().equals("运行")){
				pcbList.get(i).setState("销毁");
				System.out.println("您强制销毁了当前运行的进程"+pcbList.get(i).getPid());
				break;
			}
		}
	}

	//挂起进程
	public void hangUpProcess(){
		for(int i = 0; i < pcbList.size(); i++){
			if(pcbList.get(i).getState().equals("运行")){
				pcbList.get(i).setState("等待");
				System.out.println("您挂起了当前运行的进程"+pcbList.get(i).getPid());
				break;
			}
		}
	}

	//激活进程
	public void activateProcess(){
		for(int i = 0; i < pcbList.size(); i++){
			if(pcbList.get(i).getState().equals("等待")){
				pcbList.get(i).setState("就绪");
				System.out.println("您激活了等待进程"+pcbList.get(i).getPid());
				break;
			}
		}
	}

	//时间片到
	public void timeUp(){
		for(int i = 0; i < pcbList.size(); i++){
			if(pcbList.get(i).getState().equals("运行")){
				pcbList.get(i).setState("就绪");
				System.out.println("进程"+pcbList.get(i).getPid()+"的时间片到，转为就绪状态");
				break;
			}
		}
	}
}

测试数据：

实验结果