maincanvas.java

J2ME编程的50个例子,适合掌上系统的编程

package demo;
import SubmarineMidlet;

import java.util.Random;

import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Displayable;
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.lcdui.game.Sprite;

public class MainCanvas extends GameCanvas 
				implements Runnable, CommandListener{
	public static final int GAME_UI				= 0;	//进入用户界面
	public static final int GAME_GAMING			= 1;	//进行游戏
	public static final int GAME_BUTTON			= 2;	//游戏时显示界面按钮
	public static final int GAME_END				= 3;	//游戏结束
	public static final int GAME_STATE_NUM 		= 4;	//状态总数
	private int m_nState	= GAME_UI;						//存储当前的游戏状态
	
	private boolean		m_bRunning;			    		//控制线程运行
	private MyUI			m_UI;							//界面对象
	private MyBack			m_Back;							//背景对象
	private ShipSprite 	m_Ship;							//战舰对象
	private SubSprite 		m_aSub[];						//潜艇对象
	private ExplosionSprite m_aExplosion[];				//爆炸对象
	private Random			m_Random;						//随机数对象
	private LayerManager m_LayerManager;					//层管理器对象
	private int			m_nDestroyNum;					//摧毁的潜艇树木
	private Sprite			m_TextSp;						//图形文字对象
	private Command MenuCommand;							//高级按钮对象
	public MainCanvas( ){
		super(true);			
		try{
			//创建用户界面，并设置界面中的按钮
			MyButton button = new MyButton(41, 21, 0, 1, -1, -1, -1, 2);
			m_UI = new MyUI(button);
        }
        catch(Exception exception){}
        setState(GAME_UI);
		Start();
	}
	private void Reset(){	
		//创建随机数对象
		if( m_Random == null )
			m_Random = new Random();
		if( m_Ship == null )
		{
			m_aSub 			= new SubSprite[4];
			m_aExplosion 	= new ExplosionSprite[5];
			try{ 
				//创建战舰对象
				Image image = Image.createImage("/demo/ship.png");
				m_Ship = new ShipSprite( image, 50, 20 );
				//创建潜水艇对象
				image = Image.createImage("/demo/sub.png");
				for( int n = 0; n < m_aSub.length; n ++ ){
					m_aSub[n] = new SubSprite( image, 26, 10 );
				}
				//创建爆炸对象
				image = Image.createImage("/demo/explosion.png");
				for( int m = 0; m < m_aExplosion.length; m ++ ){
					m_aExplosion[m] = new ExplosionSprite( image, 32, 32 );
				}
			}
		    catch(Exception e){}
		}
	    if( m_LayerManager == null )
	    {//创建层管理器，并将所有图层添加到管理器
	    	m_LayerManager = new LayerManager();
		    for( int m = 0; m < m_aExplosion.length; m ++ )
		    {
		    	m_LayerManager.append(m_aExplosion[m]);
		    }
		    m_LayerManager.append( m_Ship );
		    m_LayerManager.append( m_Ship.m_Missile );
		    for( int n = 0; n < m_aSub.length; n ++ )
		    {
		    	m_LayerManager.append(m_aSub[n]);
		    	m_LayerManager.append(m_aSub[n].m_Missile);
			}
	    }
	    
		//设置战舰的位置
	    m_Ship.setRefPixelPosition( getWidth()/2, getHeight()/2 - 20 );
	    m_nDestroyNum = 0;

		//创建背景
		if( m_Back == null )
			m_Back = new MyBack();
        if( MenuCommand == null ){
        	//创建菜单
        	MenuCommand = new Command("Menu", Command.OK, 0);
        	addCommand(MenuCommand);
            setCommandListener(this);
        }
        if( m_TextSp == null ){
        	//创建图形文字对象
        	try{
        		Image img = Image.createImage("/demo/text.png");
        		m_TextSp = new Sprite(img, 82, 25);
        		m_TextSp.defineReferencePixel(41, 23);
        		int x = getWidth()/2;
        		int y = getHeight()/2 - 10;
        		m_TextSp.setRefPixelPosition(x, y);
        	}
        	catch(Exception exception){}
        }
        
	}
	private void setState( int state ){					//设置游戏状态
		if( state < 0 || state >= GAME_STATE_NUM )
			return;
		m_nState = state;
		switch( m_nState ){
		case GAME_UI:										//进入用户界面
			m_UI.setState(MyUI.UI_TITLE);					//显示标题界面
			//设置本游戏的按钮类型，本游戏有:开始、退出两种按钮
			m_UI.getButton().setShow(true, false, false, false, false, true );
			break;
		case GAME_BUTTON:									//在游戏中途显示按钮
			m_UI.setState(MyUI.UI_BUTTON);
			//游戏中途，显示复位与退出按钮
			m_UI.getButton().setShow(false, true, false, false, false, true );
			break;
		case GAME_GAMING:									//正在游戏
			addCommand(MenuCommand);
			m_UI.setState(MyUI.UI_HIDE);
			break;
		case GAME_END:										//游戏结束
			m_UI.setState(MyUI.UI_HIDE);
			break;;
		}
	}
	public void Start(){
		m_bRunning = true;
		Thread thread = new Thread(this);	//分配新线程
		thread.start();						//线程启动
	}
	public void run() {
		//得到系统当前时间,并将时间换算成毫秒
		long T1 = System.currentTimeMillis();
		long T2 = T1;
		while(m_bRunning){
			T2 = System.currentTimeMillis();
			if( T2 - T1 > 100 ){			//间隔100毫秒
				T1 = T2;
				Input();
				Logic();
				Paint();
			}
		}
	}
	public void Stop(){
		m_bRunning = false;
	}
	public void Input(){
		int keyStates = getKeyStates();
		switch( m_nState ){
		case GAME_UI:
			{
				switch( m_UI.Input( keyStates ) ){
				case MyButton.BUTTON_START:					//按下开始键
					Reset();
					setState(GAME_GAMING);
					break;
				case MyButton.BUTTON_EXIT:					//按下退出键
					SubmarineMidlet.midlet.notifyDestroyed();
					break;
				}
			}
			break;			
		case GAME_GAMING:									//游戏中
			m_Ship.Input(keyStates, getWidth(), getHeight());
			break;
		case GAME_BUTTON:									//游戏中途显示按钮
			{
				switch( m_UI.Input( keyStates ) ){
				case MyButton.BUTTON_RESET:					//按下复位键
					Reset();
					setState(GAME_GAMING);
					break;
				case MyButton.BUTTON_EXIT:					//按下退出键
					SubmarineMidlet.midlet.notifyDestroyed();
					break;
				}
			}
			break;
		case GAME_END:
			break;
		}
	}
	public void Logic(){
		switch( m_nState ){		
		case GAME_GAMING:									//游戏中
			//爆炸逻辑
			for( int m = 0; m < m_aExplosion.length; m ++ ){
				m_aExplosion[m].Logic();
			}
			//战舰逻辑
			m_Ship.Logic( getWidth(), getHeight() );
			//潜艇逻辑
		    for( int n = 0; n < m_aSub.length; n ++ ){
		    	m_aSub[n].Logic(getWidth(), getHeight());
			}
		    //碰撞检测
		    CheckCollision();
		    //产生新的潜水艇
		    CreateSub();
			break;
		default:
			break;
		}
		
	}
	public void Paint(){
		Graphics g = getGraphics();
		//用黑色清屏
		g.setColor(0);
		g.fillRect( 0, 0, getWidth(), getHeight() );
		
		g.setColor(0xFFFF0000);
		switch( m_nState ){
		case GAME_UI:								//显示界面
			m_UI.Paint(g, getWidth(), getHeight());
			break;			
		case GAME_GAMING:							//显示游戏画面
		case GAME_BUTTON:
		case GAME_END:
			m_Back.Paint(g, getWidth(), getHeight());
			m_LayerManager.paint(g, 0, 0);
			//显示分数
			StringBuffer buf = new StringBuffer();
			buf.append("Score:");
			buf.append(m_nDestroyNum);
			g.drawString(buf.toString(), 5, 5, 0);
			if( m_nState == GAME_END )
				m_TextSp.paint(g);
			m_UI.Paint(g, getWidth(), getHeight());
			break;
		}
		flushGraphics();
	}
	public void commandAction(Command c, Displayable s){
		if( c == MenuCommand ){
			switch( m_nState ){	
			case GAME_END:							//游戏结束，显示按钮
			case GAME_GAMING:						//正在游戏，显示按钮	
				setState(GAME_BUTTON);
				break;
			case GAME_BUTTON:						//正显示按钮，退回游戏
				setState(GAME_GAMING);
				break;
			default:
				break;
			}
		}
	}
	//碰撞检测
	private void CheckCollision()
	{
		for( int n = 0; n < m_aSub.length; n ++ ){
			//潜艇的导弹和战舰碰撞
			if( m_aSub[n].m_Missile.collidesWith( m_Ship, true ) ){
				m_aSub[n].m_Missile.setVisible(false);
				CreateExplosion(m_aSub[n].m_Missile.getRefPixelX(), 
						m_aSub[n].m_Missile.getRefPixelY());
				//游戏失败
				m_TextSp.setFrame(1);
				setState(GAME_END);
				break;
			}
			//我方子弹和敌人坦克碰撞
			if( m_Ship.m_Missile.collidesWith( m_aSub[n], true ) ){
				m_nDestroyNum ++;
				CreateExplosion(m_Ship.m_Missile.getRefPixelX(), 
						m_Ship.m_Missile.getRefPixelY());
				m_Ship.m_Missile.setVisible( false );
				m_aSub[n].setVisible( false );
			}
		}
	}
	//随机产生潜艇
	public void  CreateSub() {
		//以5分之一的概率产生潜艇
		int nRs = m_Random.nextInt() % 5;
		if( Math.abs(nRs) != 0 )
			return;
		//如果某一位置的潜艇被摧毁，则可以产生新潜艇
		for( int n = 0; n < m_aSub.length; n ++ ){
	    	if( m_aSub[n].isVisible() )
	    		continue;
	    	int x = - m_aSub[n].getWidth();
	    	boolean bRight = true;
	    	int rand = m_Random.nextInt();
	    	m_aSub[n].setFrame(0);
	    	if( rand < 0 ){
	    		x = getWidth() + m_aSub[n].getWidth();
		    	bRight = false;
		    	m_aSub[n].setFrame(1);
	    	}
	    	int y = m_Random.nextInt() % (getHeight()/2 - 15);
	    	y = Math.abs(y) + getHeight()/2;
	    	
	    	m_aSub[n].Start(x, y, bRight, 2);
	    	break;
		}
	}
	//产生爆炸，参数nX、nY分别是爆炸位置的横纵坐标
	public void CreateExplosion( int nX, int nY ){
		for( int m = 0; m < m_aExplosion.length; m ++ ){
	    	if( m_aExplosion[m].isVisible() )
	    		continue;
	    	m_aExplosion[m].Start( nX, nY );
	    	break;
		}
	}
}