board.java

J2ME核心类及MIDlet类 MIDP用户界面对象 图形处理及低级事件处理 多线程编程 I/O及网络编程 数据库RMS编程 浮点数编程 多媒体及GAME API编程 安全、加密及

import java.util.Random;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.MIDlet;
import javax.microedition.lcdui.game.*;

public class Board extends GameCanvas 
	implements CommandListener, Runnable {

	static final int ROWS = 4;
	static final int COLS = 4;
	Piece[] pieces;
	Piece blank;
	int cellw = 24, cellh = 24, cellx = 30, celly = 20;
	int cellxoff = 7, cellyoff = 4;
	Font font = Font.getFont(Font.FACE_SYSTEM,
		Font.STYLE_PLAIN, Font.SIZE_MEDIUM);
	Random rand = new Random();

	Thread thread;
	Command exitCmd, resetCmd;
	MIDlet midlet;

	class Piece {
		String caption;
		int row;
		int col;
		public Piece(String caption, int row, int col) {
			this.caption = caption;
			this.row = row;
			this.col = col;
		}
		void paint(Graphics g) {
			int px = col * cellw + cellx;
			int py = row * cellh + celly;

			if (caption != null) {
				g.setColor(0);
				g.setFont(font);
				g.drawRect(px, py, cellw-2, cellh-2);
				g.drawString(caption,
					px+cellxoff, py+cellyoff,
					Graphics.TOP|Graphics.LEFT);
			}
		}
	}


	public Board(MIDlet midlet_) {
		super( true );
		midlet = midlet_;

		pieces = new Piece[ ROWS * COLS ];
		for(int i=0; i<ROWS; i++ )
			for(int j=0; j<COLS; j++ ) {
				String caption = ""+(i*COLS+j+1); 
				if( i==ROWS-1 && j==COLS-1 ) caption = null;
				// 这里用数字作标题，最后一块的标题为空
				pieces[i*COLS + j] = new Piece( caption, i, j );
		}
		blank = pieces[ROWS * COLS - 1];
		
		exitCmd = new Command("退出", Command.EXIT, 0);
		resetCmd = new Command( "开始", Command.SCREEN, 1);
		addCommand( exitCmd );
		addCommand( resetCmd );
		setCommandListener(this);
	}

	public void commandAction(Command c, Displayable d) {
		if( c==exitCmd ) {
			midlet.notifyDestroyed();
		}else if( c==resetCmd ) {
			resetGrid();
		}
	}

	// 重置格子，随机交换一些格子的位置
	void resetGrid() {
		for( int i=0; i<100; i++ )
		{
			int a = randRange( ROWS*COLS );
			int b = randRange( ROWS*COLS );
			swap( a, b );
		}
	}

	// 产生一个随机数
	int randRange(int n) {
		int r = rand.nextInt() % n;
		if (r < 0)
			r += n;
		return r;
	}
	
	// 交换两个方块
	void swap( int a, int b )
	{
		int t;
		t=pieces[a].row; 
		pieces[a].row=pieces[b].row; 
		pieces[b].row = t;
		t=pieces[a].col; 
		pieces[a].col=pieces[b].col; 
		pieces[b].col = t;
	}

	public void paint( Graphics g )
	{
		flushGraphics();
	}

	// 绘制
	public void paintAll(Graphics g) {
		g.setColor(0xFFFFFF);
		g.fillRect(0, 0, getWidth(), getHeight());
			
		g.setColor(0);
		g.drawRect(cellx-2, celly-2, 
			COLS*cellw + 3, ROWS*cellh + 3);

		for (int i = 0; i < ROWS*COLS; i++) {
			pieces[i].paint(g);
		}
	}

	public void showNotify() {
		thread = new Thread(this);
		thread.start();
	}
	public void hideNotify() {
		thread = null;
	}

	public void run() {
		Graphics g = getGraphics(); // 后台grahpics对象
		Thread mythread = Thread.currentThread();
		while (mythread == thread ) {
			// 检查键盘的状态，并进行适当的处理
			int keyState = getKeyStates();
			if ((keyState & LEFT_PRESSED) != 0) {
				moveLeft();
				System.out.println( "L" );
			}
			else if ((keyState & RIGHT_PRESSED) != 0) {
				moveRight();
				System.out.println( "R" );
			}
			else if ((keyState & UP_PRESSED) != 0) {
				moveUp();
				System.out.println( "U" );
			}
			else if ((keyState & DOWN_PRESSED) != 0) {
				moveDown();
				System.out.println( "D" );
			}

			// 绘制相应的图形
			paintAll(g);
			// 刷新屏幕
			flushGraphics();
			
			// 等待键状态的改变
			int cnt = 1;
			while( getKeyStates() == keyState )
			{
				try{ Thread.sleep(10);}
				catch(Exception e){}
				cnt ++;
				if( cnt > 100 ) break; // 最久等1秒
			}
			//synchronized(this) {
			//	try {
			//		wait(100);
			//	} catch(Exception e) {}
			//}
		}
	}
	
	void moveLeft(){
		if( blank.col==COLS-1 ) return;
		for( int i=0; i<ROWS*COLS; i++ )
			if( pieces[i].row == blank.row && 
				pieces[i].col == blank.col + 1 ){
					swap( i, ROWS*COLS-1 );
					break;
		}
	}
	void moveRight(){
		if( blank.col==0 ) return;
		for( int i=0; i<ROWS*COLS; i++ )
			if( pieces[i].row == blank.row && 
				pieces[i].col == blank.col - 1 ){
					swap( i, ROWS*COLS-1 );
					break;
		}
	}
	void moveUp(){
		if( blank.row==ROWS-1 ) return;
		for( int i=0; i<ROWS*COLS; i++ )
			if( pieces[i].col == blank.col && 
				pieces[i].row == blank.row + 1 ){
					swap( i, ROWS*COLS-1 );
					break;
		}
	}
	void moveDown(){
		if( blank.row==0 ) return;
		for( int i=0; i<ROWS*COLS; i++ )
			if( pieces[i].col == blank.col && 
				pieces[i].row == blank.row - 1 ){
					swap( i, ROWS*COLS-1 );
					break;
		}
	}

}