maincanvas.java

用J2ME开发的射击游戏

import java.io.IOException;
import java.util.Random;

import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Font;
import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.Image;
import javax.microedition.lcdui.game.GameCanvas;
import javax.microedition.lcdui.game.LayerManager;
import javax.microedition.rms.RecordStore;
/*
 * Created on 2006-4-22
 *
 * TODO To change the template for this generated file go to
 * Window - Preferences - Java - Code Style - Code Templates
 */

/**
 * @author 张玮
 *
 * TODO To change the template for this generated type comment go to
 * Window - Preferences - Java - Code Style - Code Templates
 */
public class MainCanvas extends GameCanvas implements Runnable,CommandListener{
	private Command 			ExitCommand;
	private PlaneMidlet 		midlet;
	private boolean 			m_bGameEnd = false;
	private int 				m_nHighScore = 0;
	private int 				m_nScore = 0;
	private MyPlane 			m_MyPlane;
	private Enemy 				m_aEnemy[];
	private BlastSprite		m_aBlast[];
	private LayerManager		m_LayerManager;
	private Image				m_BackImage;
	private Random				m_Random;
	public static int			m_nScrWidth;
	public static int 		m_nScrHeight;
	
	public MainCanvas( PlaneMidlet mMidlet )
	{
		super(true);
		midlet = mMidlet;
		ExitCommand = new Command("Exit", Command.EXIT, 0);
		addCommand(ExitCommand);
		setCommandListener(this);
		m_nScrWidth = getWidth();
		m_nScrHeight = getHeight();
		m_Random = new Random();
		m_LayerManager = new LayerManager();
		try{
			m_BackImage = Image.createImage("/Back.png");
			Image img = Image.createImage("/Blast.png");
			m_aBlast = new BlastSprite[5];
			for( int n = 0; n < m_aBlast.length; n ++ ){
				m_aBlast[n] = new BlastSprite( img, 21, 17 );
				m_LayerManager.append( m_aBlast[n] );
			}
			img = null;
			img = Image.createImage("/MyPlane.png");
			m_MyPlane = new MyPlane( img, 30, 20 );
			int nX = getWidth() / 2;
			int nY = getHeight() - 30;
			m_MyPlane.setRefPixelPosition( nX, nY );
			m_MyPlane.setVisible( true );
			m_LayerManager.append( m_MyPlane );
			m_LayerManager.append( m_MyPlane.m_Bullet );
			img = null;
			img = Image.createImage("/Enemy.png");
			m_aEnemy = new Enemy[8];
			for( int n = 0; n < m_aEnemy.length; n ++ ){
				m_aEnemy[n] = new Enemy( img, 15, 15 );
				m_LayerManager.append( m_aEnemy[n] );
				m_LayerManager.append( m_aEnemy[n].m_Bullet );
			}
		}
		catch (IOException e){}
		LoadHighScore();
		Thread thread = new Thread(this);
		thread.start();
	}
	public void Input(){
		int keyStates = getKeyStates();
		m_MyPlane.Input( keyStates );
	}
	public void Logic(){
		m_MyPlane.Logic();
		for( int n = 0; n < m_aEnemy.length; n ++ )
			m_aEnemy[n].Logic();
		for( int n = 0; n < m_aBlast.length; n ++ )
			m_aBlast[n].Logic();
		CreateEnemy();
		CheckCollisions();
	}
	
	protected void Paint() 
	{
		Graphics g = getGraphics();
		g.setColor(0);
		g.fillRect( 0, 0, getWidth(), getHeight() );
		if( m_BackImage != null ){
			int nBgX = (getWidth() - m_BackImage.getWidth() )/ 2;
			int nBgY = (getHeight() - m_BackImage.getHeight()) / 2;
			g.drawImage( m_BackImage, nBgX, nBgY, Graphics.TOP|Graphics.LEFT );
		}
		//m_LayerManager.paint( g, 0, 0 );
		for( int n = 0; n < m_aBlast.length; n ++ ){
			m_aBlast[n].paint( g );
		}
		for( int n = 0; n < m_aEnemy.length; n ++ ){
			m_aEnemy[n].paint( g );
			m_aEnemy[n].m_Bullet.paint(g);
		}
		m_MyPlane.paint(g);
		m_MyPlane.m_Bullet.paint(g);
		if( m_bGameEnd ){
			Font mFont = g.getFont();
			StringBuffer temp = new StringBuffer();
			temp.append("游戏结束，本次得分：");
			temp.append(m_nScore);
			int nX = getWidth() / 2;
			int nY = getHeight() / 2 - mFont.getHeight();
			g.drawString( temp.toString(), nX, nY, Graphics.TOP|Graphics.HCENTER );
			temp = null;
			temp = new StringBuffer();
			temp.append("历史最高分：");
			temp.append(m_nHighScore);
			nY = getHeight() / 2 + mFont.getHeight();
			g.drawString( temp.toString(), nX, nY, Graphics.TOP|Graphics.HCENTER );
		}
		flushGraphics();
	}
	public void commandAction(Command c, Displayable s)
	{
		if (c.getCommandType() == Command.EXIT)
		{
			midlet.notifyDestroyed();
		}
	}
	public void run() {
		long lTime1 = System.currentTimeMillis();
		long lTime2 = lTime1;
		try{
			while(true){
				lTime2 = System.currentTimeMillis();;
				if( lTime2 - lTime1 > 50 ){
					lTime1 = lTime2;
					Input();
					Logic();
					Paint();
				}
			}
		}
		catch(Exception e){}
	}
	public void EndGame(){
		m_bGameEnd = true;
		if( m_nScore > m_nHighScore ){
			m_nHighScore = m_nScore;
			SaveHighScore( m_nHighScore );
		}
	}
	private void SaveHighScore( int nHighScore ){
		try
		{
			byte b[] = new byte[4];
			int temp = nHighScore;
			//用一个循环将一个int型数据(4字节)，存放在b[]中
			for (int i = b.length - 1; i >= 0; i--)
			{
				b[i] = new Integer(temp & 0xff).byteValue();
			    temp = temp >> 8;
			}
			RecordStore rs = RecordStore.openRecordStore("BattlePlane",true);
			if( rs.getNumRecords() > 0 )
			{			
				int nID = rs.getNextRecordID();
				rs.setRecord(nID, b, 0, b.length);	
			}
			else
			{
				rs.addRecord(b,0,b.length);
			}
		}
		catch (Exception ex)
		{
		}
	}
	private int LoadHighScore()
	{
		int nHighScore = 0;
		try
		{
			RecordStore rs = RecordStore.openRecordStore("BattlePlane",true);
			if ( rs.getNumRecords() > 0)
			{
				int nID = rs.getNextRecordID();
				byte b[] = rs.getRecord(nID);
				if( b != null && b.length == 4 )
				{
					for (int i = 0; i < 3; i++)
		            {
						nHighScore += b[i];
		                if( b[i] < 0 )
		                	m_nHighScore += 256 + b[i];
		                nHighScore *= 256;
		            }

					nHighScore += b[3];
		            if( b[3] < 0 )
		            	nHighScore += 256;
				}
			}
		}
		catch (Exception ex){}
		return nHighScore;
	}
	
	private void CreateEnemy(){
		int RS = Math.abs(m_Random.nextInt() % 20);
		if( RS != 0 )
			return;
		for( int n = 0; n < m_aEnemy.length; n ++ ){
			if( m_aEnemy[n].isVisible() )
				continue;
			int nX = m_Random.nextInt();
			nX = Math.abs( nX % ( getWidth() - 10 ) ) + 5;
			int nSpeedX = m_Random.nextInt() % 2;
			int nSpeedY = Math.abs( m_Random.nextInt() % 2 ) + 1;
			m_aEnemy[n].SetSpeed( nSpeedX, nSpeedY );
			m_aEnemy[n].setRefPixelPosition( nX, 0 );
			m_aEnemy[n].setVisible(true);
			return;
		}
	}
	private void CreateBlast( int nX, int nY ){
		for( int n = 0; n < m_aBlast.length; n ++ ){
			if( m_aBlast[n].isVisible() )
				continue;
			m_aBlast[n].setRefPixelPosition( nX, nY );
			m_aBlast[n].setFrame(0);
			m_aBlast[n].setVisible(true);
			return;
		}
		m_aBlast[0].setRefPixelPosition( nX, nY );
		m_aBlast[0].setFrame(0);
		m_aBlast[0].setVisible(true);
	}
	private void CheckCollisions(){
		for( int n = 0; n < m_aEnemy.length; n ++ ){
			//我方飞机与敌人炮弹碰撞
			if( m_MyPlane.collidesWith( m_aEnemy[n].m_Bullet, true ) ){
				CreateBlast( m_MyPlane.getRefPixelX(), 
						m_MyPlane.getRefPixelY() );
				m_aEnemy[n].m_Bullet.setVisible(false);
				EndGame();
				return;
			}
			//我方炮弹与敌人碰撞
			if( m_MyPlane.m_Bullet.collidesWith( m_aEnemy[n], true ) ){
				CreateBlast( m_aEnemy[n].getRefPixelX(), 
						m_aEnemy[n].getRefPixelY() );
				m_nScore ++;
				m_aEnemy[n].setVisible(false);
				m_MyPlane.m_Bullet.setVisible(false);
				
			}
		}
	}
}