wormscore.java

用于移动设备上的java虚拟机源代码

/*
 * @(#)WormScore.java	1.6 02/07/25 @(#)
 *
 * Copyright (c) 2001 Sun Microsystems, Inc.  All rights reserved.
 * PROPRIETARY/CONFIDENTIAL
 * Use is subject to license terms.
 */

/*
 * WormScore.java
 *
 * Created on March 30, 2001, 16:15
 * @author Todd M Kennedy
 * @version 1.0
 */

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];
    }

}