androidSnake（阅读源码)

package edu.hhxy.android.snake;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class Snake extends Activity {
    private SnakeView mSnakeView;
    private static String ICICLE_KEY = "snake-view";
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.snake_layout);

        mSnakeView = (SnakeView) findViewById(R.id.snake);
        mSnakeView.setTextView((TextView) findViewById(R.id.text));

        if (savedInstanceState == null) {
            // We were just launched -- set up a new game
            mSnakeView.setMode(SnakeView.READY);
        } else {
            // We are being restored
            Bundle map = savedInstanceState.getBundle(ICICLE_KEY);
            if (map != null) {
                mSnakeView.restoreState(map);
            } else {
                mSnakeView.setMode(SnakeView.PAUSE);
            }
        }
    }

    @Override
    protected void onPause() {
        super.onPause();
        // Pause the game
        mSnakeView.setMode(SnakeView.PAUSE);
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        // Store the game state
        outState.putBundle(ICICLE_KEY, mSnakeView.saveState());
    }
}

package edu.hhxy.android.snake;

import java.util.ArrayList;
import java.util.Random;

import android.annotation.SuppressLint;
import android.content.Context;
import android.content.res.Resources;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.util.Log;
import android.view.KeyEvent;
import android.view.View;
import android.widget.TextView;
import edu.hhxy.android.utils.Coordinate;
import edu.hhxy.android.utils.SnakeDataUtils;

@SuppressLint("HandlerLeak")
public class SnakeView extends TileView {
    private SnakeDataUtils snakeDataUtils = new SnakeDataUtils();
    private static final String TAG = "SnakeView";
    // mMode一个变量表示，用于确定游戏是PAUSE、READY、RUNNING、LOSE
    private int mMode = READY;
    public static final int PAUSE = 0;
    public static final int READY = 1;
    public static final int RUNNING = 2;
    public static final int LOSE = 3;

    // mDirection 当前蛇头的方向，蛇头方向有NORTH、SOUTH、EAST、WEST
    private int mDirection = NORTH;
    private int mNextDirection = NORTH;
    private static final int NORTH = 1;
    private static final int SOUTH = 2;
    private static final int EAST = 3;
    private static final int WEST = 4;

    // 什么颜色的苹果RED_STAR红、YELLOW_STAR黄、GREEN_STAR绿
    private static final int RED_STAR = 1;
    private static final int YELLOW_STAR = 2;
    private static final int GREEN_STAR = 3;

    // mScore:当前得分
    private long mScore = 0;
    // 刷新屏幕的时间
    private long mMoveDelay = 600;
    // 最后一次移动的时间，用now-mLastMove可知已经刷新了多长时间
    private long mLastMove;

    /**
     * mStatusText: text shows to the user in some run states
     */
    private TextView mStatusText;

    /**
     * mSnakeTrail: 蛇链表 mAppleList: 苹果链表
     */
    private ArrayList<Coordinate> mSnakeTrail = new ArrayList<Coordinate>();
    private ArrayList<Coordinate> mAppleList = new ArrayList<Coordinate>();
    // 随机数产生类
    private static final Random RNG = new Random();

    // 线程，定时刷新屏幕
    private RefreshHandler mRedrawHandler = new RefreshHandler();

    class RefreshHandler extends Handler {
        public void handleMessage(Message msg) {
            SnakeView.this.update();
            SnakeView.this.invalidate();
        }

        public void sleep(long delayMillis) {
            this.removeMessages(0);
            sendMessageDelayed(obtainMessage(0), delayMillis);
        }
    };

    // 重写父类构造方法
    public SnakeView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initSnakeView();
    }

    public SnakeView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        initSnakeView();
    }

    // 初始化
    private void initSnakeView() {
        setFocusable(true);

        Resources r = this.getContext().getResources();
        // 初始化并加载图片
        resetTiles(4);
        loadTile(RED_STAR, r.getDrawable(R.drawable.redstar));
        loadTile(YELLOW_STAR, r.getDrawable(R.drawable.yellowstar));
        loadTile(GREEN_STAR, r.getDrawable(R.drawable.greenstar));

    }

    private void initNewGame() {
        mSnakeTrail.clear();// 新游戏开始，清空list
        mAppleList.clear();

        // For now we‘re just going to load up a short default eastbound snake
        // that‘s just turned north

        mSnakeTrail.add(new Coordinate(7, 7));
        mSnakeTrail.add(new Coordinate(6, 7));
        mSnakeTrail.add(new Coordinate(5, 7));
        mSnakeTrail.add(new Coordinate(4, 7));
        mSnakeTrail.add(new Coordinate(3, 7));
        mSnakeTrail.add(new Coordinate(2, 7));
        mNextDirection = NORTH;

        // 添加两个苹果，准备被蛇吃
        addRandomApple();
        addRandomApple();

        mMoveDelay = 600;
        mScore = 0;
    }

    // 保存下蛇和苹果的坐标，蛇的方向，分数，延迟时间等信息
    public Bundle saveState() {
        Bundle map = new Bundle();

        map.putIntArray("mAppleList",
                snakeDataUtils.coordArrayListToArray(mAppleList));
        map.putInt("mDirection", Integer.valueOf(mDirection));
        map.putInt("mNextDirection", Integer.valueOf(mNextDirection));
        map.putLong("mMoveDelay", Long.valueOf(mMoveDelay));
        map.putLong("mScore", Long.valueOf(mScore));
        map.putIntArray("mSnakeTrail",
                snakeDataUtils.coordArrayListToArray(mSnakeTrail));

        return map;
    }

    // 存储数据
    public void restoreState(Bundle icicle) {
        setMode(PAUSE);

        mAppleList = snakeDataUtils.coordArrayToArrayList(icicle
                .getIntArray("mAppleList"));
        mDirection = icicle.getInt("mDirection");
        mNextDirection = icicle.getInt("mNextDirection");
        mMoveDelay = icicle.getLong("mMoveDelay");
        mScore = icicle.getLong("mScore");
        mSnakeTrail = snakeDataUtils.coordArrayToArrayList(icicle
                .getIntArray("mSnakeTrail"));
    }

    /*
     * handles key events in the game. Update the direction our snake is
     * traveling based on the DPAD. Ignore events that would cause the snake to
     * immediately turn back on itself.
     * 
     * (non-Javadoc)
     * 
     * @see android.view.View#onKeyDown(int, android.os.KeyEvent)
     */
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent msg) {

        if (keyCode == KeyEvent.KEYCODE_DPAD_UP) {
            if (mMode == READY | mMode == LOSE) {
                /*
                 * At the beginning of the game, or the end of a previous one,
                 * we should start a new game.
                 */
                initNewGame();
                setMode(RUNNING);
                update();
                return (true);
            }

            if (mMode == PAUSE) {
                /*
                 * If the game is merely paused, we should just continue where
                 * we left off.
                 */
                setMode(RUNNING);
                update();
                return (true);
            }

            if (mDirection != SOUTH) {
                mNextDirection = NORTH;
            }
            return (true);
        }

        if (keyCode == KeyEvent.KEYCODE_DPAD_DOWN) {
            if (mDirection != NORTH) {
                mNextDirection = SOUTH;
            }
            return (true);
        }

        if (keyCode == KeyEvent.KEYCODE_DPAD_LEFT) {
            if (mDirection != EAST) {
                mNextDirection = WEST;
            }
            return (true);
        }

        if (keyCode == KeyEvent.KEYCODE_DPAD_RIGHT) {
            if (mDirection != WEST) {
                mNextDirection = EAST;
            }
            return (true);
        }

        return super.onKeyDown(keyCode, msg);
    }

    /**
     * Sets the TextView that will be used to give information (such as "Game
     * Over" to the user.
     * 
     * @param newView
     */
    public void setTextView(TextView newView) {
        mStatusText = newView;
    }

    /**
     * Updates the current mode of the application (RUNNING or PAUSED or the
     * like) as well as sets the visibility of textview for notification
     * 
     * @param newMode
     */
    public void setMode(int newMode) {
        int oldMode = mMode;
        mMode = newMode;

        if (newMode == RUNNING & oldMode != RUNNING) {
            mStatusText.setVisibility(View.INVISIBLE);
            update();
            return;
        }

        Resources res = getContext().getResources();
        CharSequence str = "";
        if (newMode == PAUSE) {
            str = res.getText(R.string.mode_pause);
        }
        if (newMode == READY) {
            str = res.getText(R.string.mode_ready);
        }
        if (newMode == LOSE) {
            str = res.getString(R.string.mode_lose_prefix) + mScore
                    + res.getString(R.string.mode_lose_suffix);
        }

        mStatusText.setText(str);
        mStatusText.setVisibility(View.VISIBLE);
    }

    // 添加一个随机的苹果
    private void addRandomApple() {
        Coordinate newCoord = null;
        boolean found = false;
        while (!found) {
            // Choose a new location for our apple
            int newX = 1 + RNG.nextInt(mXTileCount - 2);
            int newY = 1 + RNG.nextInt(mYTileCount - 2);
            newCoord = new Coordinate(newX, newY);

            // 保证苹果不出现在蛇身上
            boolean collision = false;
            int snakelength = mSnakeTrail.size();
            for (int index = 0; index < snakelength; index++) {
                if (mSnakeTrail.get(index).equals(newCoord)) {
                    collision = true;
                }
            }
            // 如果出现两个苹果，保证苹果重复
            int applelength = mAppleList.size();
            for (int index = 0; index < applelength; index++) {
                if (mAppleList.get(index).equals(newCoord)) {
                    collision = true;
                }
            }
            found = !collision;
        }
        if (newCoord == null) {
            Log.e(TAG, "Somehow ended up with a null newCoord!");
        }
        mAppleList.add(newCoord);
    }

    // 更新信息
    public void update() {
        if (mMode == RUNNING) {
            long now = System.currentTimeMillis();

            if (now - mLastMove > mMoveDelay) {
                clearTiles();
                updateWalls();
                updateSnake();
                updateApples();
                mLastMove = now;
            }
            mRedrawHandler.sleep(mMoveDelay);
        }
    }

    /**
     * 给mTileGrid赋值，标识墙
     */
    private void updateWalls() {
        for (int x = 0; x < mXTileCount; x++) {
            setTile(GREEN_STAR, x, 0);
            setTile(GREEN_STAR, x, mYTileCount - 1);
        }
        for (int y = 1; y < mYTileCount - 1; y++) {
            setTile(GREEN_STAR, 0, y);
            setTile(GREEN_STAR, mXTileCount - 1, y);
        }
    }

    /**
     * 给mTileGrid赋值，标识苹果
     */
    private void updateApples() {
        for (Coordinate c : mAppleList) {
            setTile(YELLOW_STAR, c.x, c.y);
        }
    }

    /*
     * 更新蛇，因为蛇要吃苹果
     */
    private void updateSnake() {
        boolean growSnake = false;

        Coordinate head = mSnakeTrail.get(0);// 蛇头当前的位置
        Coordinate newHead = new Coordinate(1, 1);// 新蛇头，因为一会会为其赋值，所以此处可以不初始化

        mDirection = mNextDirection;// 当前蛇头的方向

        switch (mDirection) {
        case EAST: {
            newHead = new Coordinate(head.x + 1, head.y);
            break;
        }
        case WEST: {
            newHead = new Coordinate(head.x - 1, head.y);
            break;
        }
        case NORTH: {
            newHead = new Coordinate(head.x, head.y - 1);
            break;
        }
        case SOUTH: {
            newHead = new Coordinate(head.x, head.y + 1);
            break;
        }
        }

        // 检测蛇是否撞墙
        if ((newHead.x < 1) || (newHead.y < 1) || (newHead.x > mXTileCount - 2)
                || (newHead.y > mYTileCount - 2)) {
            setMode(LOSE);
            return;

        }

        // 检测蛇是否撞自身
        int snakelength = mSnakeTrail.size();
        for (int snakeindex = 0; snakeindex < snakelength; snakeindex++) {
            Coordinate c = mSnakeTrail.get(snakeindex);
            if (c.equals(newHead)) {
                setMode(LOSE);
                return;
            }
        }

        // 吃苹果，自身涨一截，屏幕刷新变快，也就是速度变快
        int applecount = mAppleList.size();
        for (int appleindex = 0; appleindex < applecount; appleindex++) {
            Coordinate c = mAppleList.get(appleindex);
            if (c.equals(newHead)) {
                mAppleList.remove(c);
                addRandomApple();

                mScore++;
                mMoveDelay *= 0.99;

                growSnake = true;// growSnake表示蛇是否迟到苹果，判定是否自身增长
            }
        }
        /*
         * 蛇移动的过程其实就是把蛇尾放到蛇头前，然后去掉蛇尾，这期间，如果蛇吃了苹果，则蛇自身增长，否则自身不增长
         */
        mSnakeTrail.add(0, newHead);
        // 如果蛇不需要增长，减去蛇尾即可，如果需要增长，则把增长放到蛇头，不减蛇尾
        if (!growSnake) {
            mSnakeTrail.remove(mSnakeTrail.size() - 1);
        }
        // 控制使第一个苹果颜色与蛇身不同
        int index = 0;
        for (Coordinate c : mSnakeTrail) {
            if (index == 0) {
                setTile(YELLOW_STAR, c.x, c.y);
            } else {
                setTile(RED_STAR, c.x, c.y);
            }
            index++;
        }
    }
}

package edu.hhxy.android.snake;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.View;

/**
 * TileView:一个继承View的基类
 */
public class TileView extends View {
    protected static int mTileSize;// 图片大小
    protected static int mXTileCount;// 总的列数
    protected static int mYTileCount;// 总的行数
    private static int mXOffset;// x边距
    private static int mYOffset;// y边距
    private Bitmap[] mTileArray;// 图片数组

    /**
     * 二维数组,根据其值用来确定是否要画苹果，以及要画什么颜色的苹果
     */
    private int[][] mTileGrid;// 二维数组

    private final Paint mPaint = new Paint();

    /*
     * 构造方法
     */
    public TileView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        TypedArray a = context.obtainStyledAttributes(attrs,
                R.styleable.TileView);
        mTileSize = a.getInt(R.styleable.TileView_tileSize, 12);
        a.recycle();
    }

    public TileView(Context context, AttributeSet attrs) {
        super(context, attrs);
        TypedArray a = context.obtainStyledAttributes(attrs,
                R.styleable.TileView);
        mTileSize = a.getInt(R.styleable.TileView_tileSize, 12);
        a.recycle();
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        // w宽，h长
        mXTileCount = (int) Math.floor(w / mTileSize);
        mYTileCount = (int) Math.floor(h / mTileSize);

        mXOffset = ((w - (mTileSize * mXTileCount)) / 2);
        mYOffset = ((h - (mTileSize * mYTileCount)) / 2);

        mTileGrid = new int[mXTileCount][mYTileCount];
        clearTiles();
    }

    /**
     * 初始化
     */

    public void resetTiles(int tilecount) {
        mTileArray = new Bitmap[tilecount];
    }

    /**
     * 加载图片，使mTitleArray[]表示不同的图片
     */
    public void loadTile(int key, Drawable tile) {
        Bitmap bitmap = Bitmap.createBitmap(mTileSize, mTileSize,
                Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        tile.setBounds(0, 0, mTileSize, mTileSize);
        tile.draw(canvas);
        mTileArray[key] = bitmap;
    }

    /**
     * 初始化mTitleGrid[][]
     */
    public void clearTiles() {
        for (int x = 0; x < mXTileCount; x++) {
            for (int y = 0; y < mYTileCount; y++) {
                setTile(0, x, y);
            }
        }
    }

    /**
     * 把某一位置的坐标置为tileindex，以确定mTitleGrid[][]处要画的图片
     */
    public void setTile(int tileindex, int x, int y) {
        mTileGrid[x][y] = tileindex;
    }

    @Override
    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        for (int x = 0; x < mXTileCount; x += 1) {
            for (int y = 0; y < mYTileCount; y += 1) {
                if (mTileGrid[x][y] > 0) {
                    canvas.drawBitmap(mTileArray[mTileGrid[x][y]], mXOffset + x
                            * mTileSize, mYOffset + y * mTileSize, mPaint);
                }
            }
        }
    }
}

package edu.hhxy.android.utils;

public class Coordinate {

    /**
     * Simple class containing two integer values and a comparison function.
     * There‘s probably something I should use instead, but this was quick and
     * easy to build.
     * 
     */
    public int x;
    public int y;

    public Coordinate(int newX, int newY) {
        x = newX;
        y = newY;
    }

    public boolean equals(Coordinate other) {
        if (x == other.x && y == other.y) {
            return true;
        }
        return false;
    }

    @Override
    public String toString() {
        return "Coordinate: [" + x + "," + y + "]";
    }
}

package edu.hhxy.android.utils;

import java.util.ArrayList;

public class SnakeDataUtils {
    /**
     * 数据转换成以int [x1,y1,x2,y2,x3,y3...]的形式便于保存下蛇和苹果的坐标
     */
    public int[] coordArrayListToArray(ArrayList<Coordinate> cvec) {
        int count = cvec.size();
        int[] rawArray = new int[count * 2];
        for (int index = 0; index < count; index++) {
            Coordinate c = cvec.get(index);
            rawArray[2 * index] = c.x;
            rawArray[2 * index + 1] = c.y;
        }
        return rawArray;
    }

    /**
     * 数据从int [x1,y1,x2,y2,x3,y3...]恢复
     */
    public ArrayList<Coordinate> coordArrayToArrayList(int[] rawArray) {
        ArrayList<Coordinate> coordArrayList = new ArrayList<Coordinate>();

        int coordCount = rawArray.length;
        for (int index = 0; index < coordCount; index += 2) {
            Coordinate c = new Coordinate(rawArray[index], rawArray[index + 1]);
            coordArrayList.add(c);
        }
        return coordArrayList;
    }

}