病毒傳播仿真程序-Java

Bruce Young同學在家制作了一個有關病毒傳播的仿真程序，視角上挺震撼的，對於人們認識病毒傳播有很大的價值，於是這裏把源代碼分享出來（版權歸Bruce Young同學），因爲該程序實際上沒有實際的商用價值（有很大的傳播教育價值），所以這裏只做一些簡單的講解。
運行效果圖如下圖所示：

該程序主要使用Swing（ 一個爲Java設計的GUI工具包）來繪製圖形用戶界面（GUI）。
實現的步驟如下：

創建Point 類

該類用於定義繪製圖形界面上的點，代碼如下：

public class Point {
    private int x;
    private int y;

    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }

    public int getX() {
        return x;
    }

    public void setX(int x) {
        this.x = x;
    }

    public int getY() {
        return y;
    }

    public void setY(int y) {
        this.y = y;
    }
}

創建常量類

該類用於調整參數來展現不同的效果，見下方代碼：

public class Constants {
    //初始感染數量
    public static int ORIGINAL_COUNT=50;
    //傳播率
    public static float BROAD_RATE = 0.8f;
    //潛伏時間
    public static float SHADOW_TIME = 140;
    //醫院收治響應時間
    public static int HOSPITAL_RECEIVE_TIME=10;
    //醫院牀位
    public static int BED_COUNT=1000;
    //流動意向平均值
    public static float u=-0.99f;
}

創建城市類

該類用於定義一個城市。

public class City {
    private int centerX;
    private int centerY;

    public City(int centerX, int centerY) {
        this.centerX = centerX;
        this.centerY = centerY;
    }

    public int getCenterX() {
        return centerX;
    }

    public void setCenterX(int centerX) {
        this.centerX = centerX;
    }

    public int getCenterY() {
        return centerY;
    }

    public void setCenterY(int centerY) {
        this.centerY = centerY;
    }
}

創建醫院類

該類用於創建一個演示的醫院類。

public class Hospital {
    private int x=800;
    private int y=110;
    private int width;
    private int height=606;
    public int getWidth() {
        return width;
    }
    public int getHeight() {
        return height;
    }

    public int getX() {
        return x;
    }

    public int getY() {
        return y;
    }

    private static Hospital hospital = new Hospital();
    public static Hospital getInstance(){
        return hospital;
    }
    private Point point = new Point(800,100);
    private List<Bed> beds = new ArrayList<>();

    private Hospital() {
        if(Constants.BED_COUNT==0){
            width=0;
            height=0;
        }
        int column = Constants.BED_COUNT/100;
        width = column*6;

        for(int i=0;i<column;i++){

            for(int j=10;j<=610;j+=6){
                Bed bed = new Bed(point.getX()+i*6,point.getY()+j);
                beds.add(bed);

            }

        }
    }

    public Bed pickBed(){
        for(Bed bed:beds){
            if(bed.isEmpty()){
                return bed;
            }
        }
        return null;
    }
}

創建醫院的牀位類

該類創建一個用於演示的醫院的病牀類。

public class Bed extends Point{
    public Bed(int x, int y) {
        super(x, y);
    }
    private boolean isEmpty=true;

    public boolean isEmpty() {
        return isEmpty;
    }

    public void setEmpty(boolean empty) {
        isEmpty = empty;
    }
}

創建PersonPool類

該類創建PersonPool，用於管理城市大小和人數。

public class PersonPool {
    private static PersonPool personPool = new PersonPool();
    public static PersonPool getInstance(){
        return personPool;
    }

    List<Person> personList = new ArrayList<Person>();

    public List<Person> getPersonList() {
        return personList;
    }

    private PersonPool() {
        City city = new City(400,400);
        for (int i = 0; i < 5000; i++) {
            Random random = new Random();
            int x = (int) (100 * random.nextGaussian() + city.getCenterX());
            int y = (int) (100 * random.nextGaussian() + city.getCenterY());
            if(x>700){
                x=700;
            }
            Person person = new Person(city,x,y);
            personList.add(person);
        }
    }
}

創建Person類

public class Person {
    private City city;
    private int x;
    private int y;
    private MoveTarget moveTarget;
    int sig=1;


    double targetXU;
    double targetYU;
    double targetSig=50;


    public interface State{
        int NORMAL = 0;
        int SUSPECTED = NORMAL+1;
        int SHADOW = SUSPECTED+1;

        int CONFIRMED = SHADOW+1;
        int FREEZE = CONFIRMED+1;
        int CURED = FREEZE+1;
    }

    public Person(City city, int x, int y) {
        this.city = city;
        this.x = x;
        this.y = y;
        targetXU = 100*new Random().nextGaussian()+x;
        targetYU = 100*new Random().nextGaussian()+y;

    }
    public boolean wantMove(){
        double value = sig*new Random().nextGaussian()+Constants.u;
        return value>0;
    }

    private int state=State.NORMAL;

    public int getState() {
        return state;
    }

    public void setState(int state) {
        this.state = state;
    }

    public int getX() {
        return x;
    }

    public void setX(int x) {
        this.x = x;
    }

    public int getY() {
        return y;
    }

    public void setY(int y) {
        this.y = y;
    }
    int infectedTime=0;
    int confirmedTime=0;
    public boolean isInfected(){
        return state>=State.SHADOW;
    }
    public void beInfected(){
        state = State.SHADOW;
        infectedTime=MyPanel.worldTime;
    }

    public double distance(Person person){
        return Math.sqrt(Math.pow(x-person.getX(),2)+Math.pow(y-person.getY(),2));
    }

    private void freezy(){
        state = State.FREEZE;
    }
    private void moveTo(int x,int y){
        this.x+=x;
        this.y+=y;
    }
    private void action(){
        if(state==State.FREEZE){
            return;
        }
        if(!wantMove()){
            return;
        }
        if(moveTarget==null||moveTarget.isArrived()){

            double targetX = targetSig*new Random().nextGaussian()+targetXU;
            double targetY = targetSig*new Random().nextGaussian()+targetYU;
            moveTarget = new MoveTarget((int)targetX,(int)targetY);

        }


        int dX = moveTarget.getX()-x;
        int dY = moveTarget.getY()-y;
        double length=Math.sqrt(Math.pow(dX,2)+Math.pow(dY,2));

        if(length<1){
            moveTarget.setArrived(true);
            return;
        }
        int udX = (int) (dX/length);
        if(udX==0&&dX!=0){
            if(dX>0){
                udX=1;
            }else{
                udX=-1;
            }
        }
        int udY = (int) (dY/length);
        if(udY==0&&udY!=0){
            if(dY>0){
                udY=1;
            }else{
                udY=-1;
            }
        }

        if(x>700){
            moveTarget=null;
            if(udX>0){
                udX=-udX;
            }
        }
        moveTo(udX,udY);

//        if(wantMove()){
//        }


    }

    private float SAFE_DIST = 2f;

    public void update(){
        //@TODO找時間改爲狀態機
        if(state>=State.FREEZE){
            return;
        }
        if(state==State.CONFIRMED&&MyPanel.worldTime-confirmedTime>=Constants.HOSPITAL_RECEIVE_TIME){
            Bed bed = Hospital.getInstance().pickBed();
            if(bed==null){
                System.out.println("隔離區沒有空牀位");
            }else{
                state=State.FREEZE;
                x=bed.getX();
                y=bed.getY();
                bed.setEmpty(false);
            }
        }
        if(MyPanel.worldTime-infectedTime>Constants.SHADOW_TIME&&state==State.SHADOW){
            state=State.CONFIRMED;
            confirmedTime = MyPanel.worldTime;
        }

        action();

        List<Person> people = PersonPool.getInstance().personList;
        if(state>=State.SHADOW){
            return;
        }
       for(Person person:people){
           if(person.getState()== State.NORMAL){
               continue;
           }
           float random = new Random().nextFloat();
           if(random<Constants.BROAD_RATE&&distance(person)<SAFE_DIST){
               this.beInfected();
           }
       }
    }
}

創建MyPanel類

public class MyPanel extends JPanel implements Runnable {


   private int pIndex=0;

    public MyPanel() {
        this.setBackground(new Color(0x444444));
    }

    @Override
    public void paint(Graphics arg0) {
        super.paint(arg0);
        //draw border
        arg0.setColor(new Color(0x00ff00));
        arg0.drawRect(Hospital.getInstance().getX(),Hospital.getInstance().getY(),
                Hospital.getInstance().getWidth(),Hospital.getInstance().getHeight());



        List<Person> people = PersonPool.getInstance().getPersonList();
        if(people==null){
            return;
        }
        people.get(pIndex).update();
        for(Person person:people){

            switch (person.getState()){
                case Person.State.NORMAL:{
                    arg0.setColor(new Color(0xdddddd));

                }break;
                case Person.State.SHADOW:{
                    arg0.setColor(new Color(0xffee00));

                }break;
                case Person.State.CONFIRMED:
                case Person.State.FREEZE:{
                    arg0.setColor(new Color(0xff0000));

                }break;
            }
            person.update();
            arg0.fillOval(person.getX(), person.getY(), 3, 3);

        }
        pIndex++;
        if(pIndex>=people.size()){
            pIndex=0;
        }
    }

    public static int worldTime=0;
    @Override
    public void run() {
        while (true) {

            this.repaint();

            try {
                Thread.sleep(100);
                worldTime++;
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

    }


}

創建MoveTarget 類

創建MoveTarget 類用於模擬人羣流動。

public class MoveTarget {
    private int x;
    private int y;
    private boolean arrived=false;

    public MoveTarget(int x, int y) {
        this.x = x;
        this.y = y;
    }

    public int getX() {
        return x;
    }

    public void setX(int x) {
        this.x = x;
    }

    public int getY() {
        return y;
    }

    public void setY(int y) {
        this.y = y;
    }

    public boolean isArrived() {
        return arrived;
    }

    public void setArrived(boolean arrived) {
        this.arrived = arrived;
    }
}

修改入口類

修改入口類，繪製圖形

import javax.swing.*;
import java.awt.image.BufferedImage;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class Main {
 public static void main(String[] args) {
        MyPanel p = new MyPanel();
        Thread panelThread = new Thread(p);
        JFrame frame = new JFrame();
        frame.add(p);
        frame.setSize(1000, 800);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        panelThread.start();

        List<Person> people = PersonPool.getInstance().getPersonList();
        for(int i=0;i<Constants.ORIGINAL_COUNT;i++){
            int index = new Random().nextInt(people.size()-1);
            Person person = people.get(index);

            while (person.isInfected()){
                index = new Random().nextInt(people.size()-1);
                person = people.get(index);
            }
            person.beInfected();

        }


    }
}

到此完成，運行程序即可。