java可視化，實現走迷宮小遊戲（包含DFS自動尋找迷宮解）

由於一些2020年大家都知道的原因，放假在家利用閒暇之餘觀看了波波老師的可視化算法課，傳送門，收穫頗豐。

 

現對其中的迷宮尋路算法可視化進行改造和補充，做成了一個玩家自己走迷宮的程序。本程序適用於java程序員鞏固類與對象、文件讀取、事件響應、awt包中各種工具的相關概念以及對邏輯能力的鍛鍊。由於作者水平問題，本程序難免存在紕漏之處，如有提醒或者此代碼更多的補充，歡迎聯繫我vx：wjw0310。（我從來不吝惜給幫助過我的人發紅包哦~~）

數據層

本實例需要從 .txt 文件中讀取迷宮並繪製，所以先來實現文件讀取IO類 MazeData.java，該程序在構造函數運行時將外部文件讀入，並完成迷宮各種參數的初始化，注意規定了外部 .txt 文件的第一行兩個數字分別代表迷宮的行數和列數。此外還提供了各類接口來讀取或操作私有數據。

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Scanner;

public class MazeData {

    public static final char ROAD = ' ';
    public static final char WALL = '#';

    private int N, M;   // 高，寬（行，列）
    private char[][] maze;

    private int entranceX, entranceY;   // 入口
    private int exitX, exitY;   // 出口

    public boolean[][] visited; // 記錄尋路過程某位置是否被訪問過
    public boolean[][] path;    // 存儲迷宮的解
    public boolean showPath;    // 是否打印系統提示的開關

    public Position player; // 玩家所處位置

    public MazeData(String filename){
        if (filename == null)
            throw new IllegalArgumentException("Filename can not be null!");

        Scanner scanner = null;
        try {
            File file = new File(filename);
            if (!file.exists())
                throw new IllegalArgumentException("File " + filename + " doesn't exist");

            FileInputStream fis = new FileInputStream(file);
            scanner = new Scanner(new BufferedInputStream(fis), "UTF-8");

            // 讀取第一行
            String nmline = scanner.nextLine();
            String[] nm = nmline.trim().split("\\s+");    // 正則 匹配任意空白字符
            N = Integer.parseInt(nm[0]);
            M = Integer.parseInt(nm[1]);

            maze = new char[N][M];
            visited = new boolean[N][M];
            path = new boolean[N][M];
            showPath = false;

            // 讀取後續的N行
            for (int i = 0; i < N; i ++){
                String line = scanner.nextLine();

                // 每行保證有M個字符
                if(line.length() != M)
                    throw new IllegalArgumentException("Maze file " + filename + " is invalid");

                for (int j = 0; j < M; j ++) {
                    maze[i][j] = line.charAt(j);
                    visited[i][j] = false;
                    path[i][j] = false;
                }
            }
        }
        catch (IOException e){
            e.printStackTrace();
        }
        finally {
            if (scanner != null)
                scanner.close();
        }
        // 入口，第二行第一列
        entranceX = 1;
        entranceY = 0;
        // 出口，倒數第二行最後一列
        exitX = N - 2;
        exitY = M - 1;
    }

    public int N(){ return N; }
    public int M(){ return M; }
    public int getEntranceX(){return entranceX;}
    public int getEntranceY(){return entranceY;}
    public int getExitX(){return exitX;}
    public int getExitY(){return exitY;}
    public char getMaze(int i, int j){
        if (!inArea(i, j))
            throw new IllegalArgumentException("i or j is out of index in getMaze!");

        return maze[i][j];
    }

    // 判斷點(x,y)是否在迷宮中
    public boolean inArea(int x, int y){
        return x >= 0 && x < N && y >= 0 && y < M;
    }
    // 控制檯打印迷宮
    public void print(){
        System.out.println(N + " " + M);
        for(int i = 0 ; i < N ; i ++){
            for(int j = 0 ; j < M ; j ++)
                System.out.print(maze[i][j]);
            System.out.println();
        }
        return;
    }
}

將迷宮的各個位置封裝成一個類 Position.java，便於操作

public class Position {

    private int x, y;

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

    public Position(int x, int y){
        this(x, y, null);
    }

    public int getX(){ return x; }
    public int getY(){ return y; }

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

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

}

視圖層

AlgoFrame.java 是繪製界面的核心代碼，使用java的JFrame控件，在上面添加JPanel畫板，在JFrame中定義渲染方法render來調用畫板的 paintComponent 方法實現繪製，其中需要用到自己定義的繪製輔助類 AlgoVisHelper.java，在裏面封裝了繪製矩形，設置畫筆顏色，停頓等方法，也定義了一些顏色，也可以不用定義該輔助類而直接在 AlgoFrame.java 中使用awt包中的各種方法直接實現，如有需要可自行下載代碼。

import java.awt.*;
import javax.swing.*;

public class AlgoFrame extends JFrame{

    private int canvasWidth;
    private int canvasHeight;

    public AlgoFrame(String title, int canvasWidth, int canvasHeight){

        super(title);

        this.canvasWidth = canvasWidth;
        this.canvasHeight = canvasHeight;

        AlgoCanvas canvas = new AlgoCanvas();
        setContentPane(canvas);
        pack();

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setResizable(false);

        setVisible(true);
    }

    public AlgoFrame(String title){

        this(title, 1024, 768);
    }

    public int getCanvasWidth(){return canvasWidth;}
    public int getCanvasHeight(){return canvasHeight;}

    private MazeData data;
    public void render(MazeData data){
        this.data = data;
        repaint();
    }

    private class AlgoCanvas extends JPanel{

        public AlgoCanvas(){
            // 雙緩存
            super(true);
        }

        @Override
        public void paintComponent(Graphics g) {
            super.paintComponent(g);

            Graphics2D g2d = (Graphics2D)g;

            // 抗鋸齒
            RenderingHints hints = new RenderingHints(
                    RenderingHints.KEY_ANTIALIASING,
                    RenderingHints.VALUE_ANTIALIAS_ON);
            hints.put(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
            g2d.addRenderingHints(hints);

            // 具體繪製
            int w = canvasWidth / data.M(); // 寬
            int h = canvasHeight / data.N();// 高

            for (int i = 0; i < data.N(); i ++){
                for (int j = 0; j < data.M(); j ++){
                    if (data.getMaze(i,j) == MazeData.WALL)
                        AlgoVisHelper.setColor(g2d, AlgoVisHelper.LightBlue);
                    else
                        AlgoVisHelper.setColor(g2d, AlgoVisHelper.White);

                    if (data.path[i][j] && data.showPath == true)
                        AlgoVisHelper.setColor(g2d, AlgoVisHelper.Yellow);

                    if (data.player.getX() == i && data.player.getY() == j)
                        AlgoVisHelper.setColor(g2d, AlgoVisHelper.Red);

                    AlgoVisHelper.fillRectangle(g2d, j*w, i*h, w, h);
                }
            }
        }

        @Override
        public Dimension getPreferredSize(){
            return new Dimension(canvasWidth, canvasHeight);
        }
    }
}

控制層

主函數 AlgoVisualizer.java ，其中在程序運行最開始時採用了基於遞歸的DFS算法將迷宮的解事先求出，用戶按下空格則可以實現提示功能，紅色表示玩家，鍵盤上下左右控制四個方向的移動。run()方法實現了所有的動畫邏輯

import java.awt.*;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;

public class AlgoVisualizer {

    private static int DELAY = 10;
    private static int blockSide = 8;

    private MazeData data;
    private AlgoFrame frame;

    private static final int d[][] = {{-1,0},{0,1},{1,0},{0,-1}}; // 四個方向移動

	public AlgoVisualizer(String mazeFile){
	    // 初始化數據
        data = new MazeData(mazeFile);

        int sceneHeight = data.N() * blockSide;
        int sceneWidth = data.M() * blockSide;

        // 初始化視圖
        EventQueue.invokeLater(() -> {
            frame = new AlgoFrame("Maze Solver Visualization", sceneWidth, sceneHeight);
            frame.addKeyListener(new AlgoKeyListener());
            new Thread(() -> {
                run();
            }).start();
        });
    }

    public void run(){
	    setData(-1, -1, false);

	    data.player = new Position(data.getEntranceX(), data.getEntranceY());

        // 遞歸實現
        if(!autoGo(data.getEntranceX(), data.getEntranceY()))
            System.out.println("The maze has NO solution!");

        System.out.println("初始化已完成");

	    while (true){
            frame.render(data);
            AlgoVisHelper.pause(DELAY);
            setData(-1, -1, false);

            if (data.player.getX() == data.getExitX() && data.player.getY() == data.getExitY()){
                System.out.println("遊戲結束");
                frame.render(data);
                AlgoVisHelper.pause(DELAY);
                break;
            }
        }
	    setData(-1, -1, false);
    }

    // 返回值：求解是否成功
    private boolean autoGo(int x, int y){
        if(!data.inArea(x,y))
            throw new IllegalArgumentException("x,y are out of index in go function!");

        data.visited[x][y] = true;
        setData(x, y, true);

        if (x == data.getExitX() && y == data.getExitY())
            return true;

        for (int i = 0; i < 4; i ++){
            int newX = x + d[i][0];
            int newY = y + d[i][1];
            if (data.inArea(newX, newY) &&
                    data.getMaze(newX, newY) == MazeData.ROAD &&
                    !data.visited[newX][newY]){
                if (autoGo(newX, newY))
                    return true;
            }
        }
        setData(x, y, false);
        return false;
    }

    private void setData(int x, int y, boolean isPath){
	    if (data.inArea(x, y))
            data.path[x][y] = isPath;
    }

    private class AlgoKeyListener extends KeyAdapter{
	    @Override
        public void keyPressed(KeyEvent event){
	        if (event.getKeyCode() == KeyEvent.VK_LEFT){
	            System.out.println("go left");
                oneStep(data.player.getX(), data.player.getY(), 3);
            }
            else if (event.getKeyCode() == KeyEvent.VK_DOWN){
                System.out.println("go down");
                oneStep(data.player.getX(), data.player.getY(), 2);
            }
            else if (event.getKeyCode() == KeyEvent.VK_RIGHT){
                System.out.println("go right");
                oneStep(data.player.getX(), data.player.getY(), 1);
            }
            else if (event.getKeyCode() == KeyEvent.VK_UP){
                System.out.println("go up");
                oneStep(data.player.getX(), data.player.getY(), 0);
            }
            else if (event.getKeyChar() == ' '){
                System.out.println("顯示提示");
                data.showPath = !data.showPath;
            }
        }
    }

    private void oneStep(int x, int y, int direction){
        int newX = x + d[direction][0];
        int newY = y + d[direction][1];
        if (data.inArea(newX, newY) &&
                data.getMaze(newX, newY) == MazeData.ROAD){
            data.player.setX(newX);
            data.player.setY(newY);
        }
    }

    public static void main(String[] args) {
        String mazefile = "maze_101_101.txt";
        AlgoVisualizer vis = new AlgoVisualizer(mazefile);
    }
}