hcanvas.java

用java写得有个赛车游戏

import javax.microedition.lcdui.*;
import javax.microedition.lcdui.game.*;
import java.util.*;
import java.io.*;

public class HCanvas extends GameCanvas implements Runnable {
  private Display  display;
  private boolean  sleeping;
  private long     frameDelay;
  private int      inputDelay;
  private Random   rand;
  private Image    background;
  private Image    chickenHead;
  private Sprite   chickenSprite;
  private Sprite[] carSprite = new Sprite[4];
  private int[]    carYSpeed = new int[4];
  private boolean  gameOver;
  private int      numLives;
  private int      score;

  public HCanvas(Display d) {
    super(true);
    display = d;

    // Set the frame rate (30 fps)
    frameDelay = 33;

    // Clear the input delay
    inputDelay = 0;
  }
  
  public void start() {
    // Set the canvas as the current screen
    display.setCurrent(this);

    // Initialize the random number generator
    rand = new Random();

    // Initialize the game variables
    gameOver = false;
    numLives = 3;
    score = 0;

    // Initialize the background image and chicken and car sprites
    try {
      background = Image.createImage("/Highway.png");
      chickenHead = Image.createImage("/ChickenHead.png");

      chickenSprite = new Sprite(Image.createImage("/Chicken.png"), 22, 22);
      chickenSprite.setPosition(2, 77);

      carSprite[0] = new Sprite(Image.createImage("/Car1.png"));
      carSprite[0].setPosition(27, 0);
      carYSpeed[0] = 3;
      carSprite[1] = new Sprite(Image.createImage("/Car2.png"));
      carSprite[1].setPosition(62, 0);
      carYSpeed[1] = 1;
      carSprite[2] = new Sprite(Image.createImage("/Car3.png"));
      carSprite[2].setPosition(93, 67);
      carYSpeed[2] = -2;
      carSprite[3] = new Sprite(Image.createImage("/Car4.png"));
      carSprite[3].setPosition(128, 64);
      carYSpeed[3] = -5;
    }
    catch (IOException e) {
      System.err.println("Failed loading images!");
    }

    // Start the animation thread
    sleeping = false;
    Thread t = new Thread(this);
    t.start();
  }
  
  public void stop() {
    // Stop the animation
    sleeping = true;
  }
  
  public void run() {
    Graphics g = getGraphics();
    
    // The main game loop
    while (!sleeping) {
      update();
      draw(g);
      try {
        Thread.sleep(frameDelay);
      }
      catch (InterruptedException ie) {}
    }
  }

  private void update() {
    // Check to see whether the game is being restarted
    if (gameOver) {
      int keyState = getKeyStates();
      if ((keyState & FIRE_PRESSED) != 0) {
        // Start a new game
        chickenSprite.setPosition(2, 77);
        gameOver = false;
        score = 0;
        numLives = 3;
      }

      // The game is over, so don't update anything
      return;
    }

    // Process user input to move the chicken
    if (++inputDelay > 2) {
      int keyState = getKeyStates();
      if ((keyState & LEFT_PRESSED) != 0) {
        chickenSprite.move(-6, 0);
        chickenSprite.nextFrame();
      }
      else if ((keyState & RIGHT_PRESSED) != 0) {
        chickenSprite.move(6, 0);
        chickenSprite.nextFrame();
      }
      if ((keyState & UP_PRESSED) != 0) {
        chickenSprite.move(0, -6);
        chickenSprite.nextFrame();
      }
      else if ((keyState & DOWN_PRESSED) != 0) {
        chickenSprite.move(0, 6);
        chickenSprite.nextFrame();
      }
      checkBounds(chickenSprite, false);

      // Reset the input delay
      inputDelay = 0;
    }

    // See whether the chicken made it across
    if (chickenSprite.getX() > 154) {
      // Play a sound for making it safely across
      AlertType.WARNING.playSound(display);

      // Reset the chicken position and increment the score
      chickenSprite.setPosition(2, 77);
      score += 25;
    }

    // Update the car sprites
    for (int i = 0; i < 4; i++) {
      // Move the car sprites
      carSprite[i].move(0, carYSpeed[i]);
      checkBounds(carSprite[i], true);

      // Check for a collision between the chicken and cars
      if (chickenSprite.collidesWith(carSprite[i], true)) {
        // Play a sound for losing a chicken
        AlertType.ERROR.playSound(display);

        // Check for a game over
        if (--numLives == 0) {
          gameOver = true;
        } else {
          // Reset the chicken position
          chickenSprite.setPosition(2, 77);
        }

        // No need to continue updating the car sprites
        break;
      }
    }
  }

  private void draw(Graphics g) {
    // Draw the highway background
    g.drawImage(background, 0, 0, Graphics.TOP | Graphics.LEFT);
    
    // Draw the number of remaining lives
    for (int i = 0; i < numLives; i++)
      g.drawImage(chickenHead, 180 - ((i + 1) * 8), 170, Graphics.TOP | Graphics.LEFT);

    // Draw the chicken sprite
    chickenSprite.paint(g);

    // Draw the car sprites
    for (int i = 0; i < 4; i++)
      carSprite[i].paint(g);
    
    if (gameOver) {
      // Draw the game over message and score
      g.setColor(255, 255, 255); // white
      g.setFont(Font.getFont(Font.FACE_MONOSPACE, Font.STYLE_BOLD, Font.SIZE_LARGE));
      g.drawString("GAME OVER", 90, 40, Graphics.TOP | Graphics.HCENTER);
      g.setFont(Font.getFont(Font.FACE_MONOSPACE, Font.STYLE_BOLD, Font.SIZE_MEDIUM));
      g.drawString("You scored " + score + " points.", 90, 70, Graphics.TOP |
        Graphics.HCENTER);
    }

    // Flush the offscreen graphics buffer
    flushGraphics();
  }

  private void checkBounds(Sprite sprite, boolean wrap) {
    // Wrap/stop the sprite if necessary
    if (wrap) {
      // Wrap the sprite around the edges of the screen
      if (sprite.getX() < -sprite.getWidth())
        sprite.setPosition(getWidth(), sprite.getY());
      else if (sprite.getX() > getWidth())
        sprite.setPosition(-sprite.getWidth(), sprite.getY());
      if (sprite.getY() < -sprite.getHeight())
        sprite.setPosition(sprite.getX(), getHeight());
      else if (sprite.getY() > getHeight())
        sprite.setPosition(sprite.getX(), -sprite.getHeight());
    }
    else {
      // Stop the sprite at the edges of the screen
      if (sprite.getX() < 0)
        sprite.setPosition(0, sprite.getY());
      else if (sprite.getX() > (getWidth() - sprite.getWidth()))
        sprite.setPosition(getWidth() - sprite.getWidth(), sprite.getY());
      if (sprite.getY() < 0)
        sprite.setPosition(sprite.getX(), 0);
      else if (sprite.getY() > (getHeight() - sprite.getHeight()))
        sprite.setPosition(sprite.getX(), getHeight() - sprite.getHeight());
    }
  }
}