Java手机游戏编程之MIDP图形设计篇（6）

6、Game.java

　　 这个类封装了九宫格游戏的主要的游戏程序逻辑。前面我们也说过，游戏程序逻辑本身并不在本例程重点讨论的范围之内，本文主要是介绍MIDP图形编程的基础知识。游戏程序逻辑的WINS数组部分来自http://java.sun.com/Applets/JDK/1.0/demo/TicTacToe/TicTacToe.java 这个经典例程。

　　 注意游戏程序逻辑是独立于游戏用户界面的(参见类GameScreen)，并且可以使用其它实现方法替代。

package example.tictactoe; import java.util.Random; import javax.microedition.midlet.*; import javax.microedition.lcdui.*; // The game logic for TicTacToe class Game { private static final int[] WINS = { // horizontals bit(0) | bit(1) | bit(2), bit(3) | bit(4) | bit(5), bit(6) | bit(7) | bit(8), // verticals bit(0) | bit(3) | bit(6), bit(1) | bit(4) | bit(7), bit(2) | bit(5) | bit(8), // diagonals bit(0) | bit(4) | bit(8), bit(2) | bit(4) | bit(6) } ; private static final int DRAWN_GAME = bit(0) | bit(1) | bit(2) | bit(3) | bit(4) | bit(5) | bit(6) | bit(7) | bit(8); private int playerState; private int computerState; private Random random; Game(Random random) { this.random = random; initialize(); } void initialize() { playerState = 0; computerState = 0; } boolean isFree(int position) { int bit = bit(position); return (((playerState & bit) == 0) && ((computerState & bit) == 0)); } // The 'Contract' is that caller will always make valid moves. // We don't check that it's the player's turn. void makePlayerMove(int position) { playerState |= bit(position); } // The 'Contract' is that we will be called only when there is still // at least one free square. int makeComputerMove() { int move = getWinningComputerMove(); if (move == -1) { // can't win move = getRequiredBlockingComputerMove(); if (move == -1) { // don't need to block move = getRandomComputerMove(); } } computerState |= bit(move); return move; } boolean isGameOver() { return isPlayerWinner() | isComputerWinner() | isGameDrawn(); } boolean isPlayerWinner() { return isWin(playerState); } boolean isComputerWinner() { return isWin(computerState); } boolean isGameDrawn() { return (playerState | computerState) == DRAWN_GAME; } // Return a winning move if there is at least one, otherwise return -1 private int getWinningComputerMove() { int move = -1; for (int i = 0; i < 9; ++i) { if (isFree(i) && isWin(computerState | bit(i))) { move = i; break; } } return move; } // Return a required blocking move if there is at least one (more // than one and we've inevitably lost), otherwise return -1 private int getRequiredBlockingComputerMove() { int move = -1; for (int i = 0; i < 9; ++i) { if (isFree(i) && isWin(playerState | bit(i))) { move = i; break; } } return move; } // Return a random move in a free square, // or return -1 if none are available private int getRandomComputerMove() { int move = -1; // determine how many possible moves there are int numFreeSquares = 0; for (int i = 0; i < 9; ++i) { if (isFree(i)) { numFreeSquares++; } } // if there is at least one possible move, pick randomly if (numFreeSquares > 0) { // shift twice to get rid of sign bit, then modulo numFreeSquares int pick = ((random.nextInt()<<1)>>>1) % numFreeSquares; // now find the chosen free square by counting pick down to zero for (int i = 0; i < 9; ++i) { if (isFree(i)) { if (pick == 0) { move = i; break; } pick--; } } } return move; } private static boolean isWin(int state) { boolean isWinner = false; for (int i = 0; i < WINS.length; ++i) { if ((state & WINS[i]) == WINS[i]) { isWinner = true; break; } } return isWinner; } private static int bit(int i) { return 1 << i; } }

7、TicTacToe.jad

　　 下面是九宫格MIDlet的应用程序描述文件。

MIDlet-Name: TicTacToe MIDlet-Vendor: Forum Nokia MIDlet-Version: 1.1.1 MIDlet-Jar-Size: 11409 MIDlet-Jar-URL: TicTacToe.jar MIDlet-1: TicTacToe, /tictactoe.png, example.tictactoe.TicTacToeMIDlet

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