wormscore.java

贪食蛇的游戏大家都玩过 这里是他的J2ME游戏完全代码

/*
 * @(#)WormScore.java	1.4 04/01/27
 *
 * Copyright (c) 2000-2004 Sun Microsystems, Inc. All rights reserved. 
 * PROPRIETARY/CONFIDENTIAL
 * Use is subject to license terms
 */

/*
 * WormScore.java
 *
 * Created on March 30, 2001, 16:15
 * @version 1.4
 */

package example.wormgame;

import java.lang.System;
import java.lang.Runnable;
import java.lang.InterruptedException;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

import javax.microedition.lcdui.Font;
import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Graphics;

import javax.microedition.rms.RecordStore;
import javax.microedition.rms.RecordStoreException;

/**
 * The WormScore keeps track of the high scores for each of the worm
 * levels. All access to the scores occur through static methods. There
 * can never be a WormScore object.
 *
 * We cache the scores and names for quick access during game play. The
 * calling application must first call openHighScores() to open the
 * score database. Finally, a closeHighScores() must be called to release
 * system resources.
 */
public class WormScore {
    /** Array of high scores for each game level. */
    private static short[] highScore = new short[WormPit.MAX_LEVELS];
    /** Array of player names for each high score level. */
    private static String[] highScoreName = new String[WormPit.MAX_LEVELS];
    /** Current score for this game. */
    private static RecordStore myStore;
    /** Is the internal score struct intialized? */
    private static boolean highScoresHaveBeenInit; /* = false; */

    /** Default constructor can not be instantiated. */
    private WormScore() {
    }

    /**
     * Initialize all high scores to 0.
     */
    private static void initializeScores() {
    /* Initialize the score store */
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    DataOutputStream dos = new DataOutputStream(baos);
    byte[] b;

    try {
        try {
        dos.writeShort(0);
        dos.writeUTF("");
        b = baos.toByteArray();
        dos.close();
        } catch (IOException ioe) {
        throw new RecordStoreException();
        }


        for (int i = 0; i < WormPit.MAX_LEVELS; i++) {
        myStore.addRecord(b, 0, b.length);
        }
    } catch (RecordStoreException rse) {
        /* Silently fail; exception to read high score is non-critical */
        closeHighScores();
    }
    }

    /**
     * Open the high score storage file. If the file doesn't exist,
     * initialize all high scores to 0.
     */
    static void openHighScores() {
    try {
        myStore = RecordStore.openRecordStore("HighScores", true);

        if (highScoresHaveBeenInit) return;

        /* Intialize the internal score structures */
        if (myStore.getNumRecords() == 0) {
        initializeScores();
        } else {
        /* Read high score store */
        ByteArrayInputStream bais;
        DataInputStream      dis;
        byte                 data[];

        for (int i = 0; i < WormPit.MAX_LEVELS; i++) {
            data = myStore.getRecord(i+1);
            if (data != null) {
            try {
                bais = new ByteArrayInputStream(data);
                dis  = new DataInputStream(bais);
                highScore[i]     = dis.readShort();
                highScoreName[i] = dis.readUTF();
                dis.close();
            } catch (IOException ioe) {
            }
            }
        }
        }
        highScoresHaveBeenInit = true;

    } catch (RecordStoreException rse) {
        /* Silently fail; exception to read high score is non-critical */
    }
    }

    /**
     * Close the high score file
     */
    static void closeHighScores() {
    if (myStore != null) {
        try {
        myStore.closeRecordStore();
        } catch (RecordStoreException frse) {
        }
        myStore = null;
    }
    }

    /**
     * Save high score for posterity.
     * @param level current game level
     * @param newScore current game score to be recorded
     * @param name current user name to be recorded
     */
    static void setHighScore(int level, int newScore, String name) {
    ByteArrayOutputStream baos;
    DataOutputStream      das;
    byte[]                data;

    /* Only save score if it's higher */
    if (newScore <= highScore[level]) {
        return;
    }

    try {
        try {
        baos = new ByteArrayOutputStream();
        das = new DataOutputStream(baos);

        das.writeShort((short)newScore);
        das.writeUTF(name);
        data = baos.toByteArray();
        das.close();
        } catch (IOException ioe) {
        throw new RecordStoreException();
        }

            if (myStore == null) {
        openHighScores();
        myStore.setRecord(level + 1, data, 0, data.length);
        closeHighScores();
        } else {
        myStore.setRecord(level + 1, data, 0, data.length);
        }
    } catch (RecordStoreException rse) {
        /* Silently fail; exception to save high score is non-critical */
    }

    highScore[level]     = (short)newScore;
    highScoreName[level] = name;
    }

    /**
     * Return the high score for a given level.
     * @param level current level for high score check
     * @return numeric value for highest score at the
     * requested level
     */
    static short getHighScore(int level) {
    if (!highScoresHaveBeenInit) {
        openHighScores();               // Force scores to be initialized
        closeHighScores();
    }
    return highScore[level];
    }

    /**
     * Return the high score name for a given level.
     * @param level current level for high score check
     * @return name for highest score at the
     * requested level
     */
    static String getHighScoreName(int level) {
    if (!highScoresHaveBeenInit) {
        openHighScores();               // Force scores to be initialized
        closeHighScores();
    }
    return highScoreName[level];
    }

}