【移动开发】Android游戏开发SurfaceView应用----手指发动小球（小球碰撞检测例子）

import android.os.Bundle;
import android.app.Activity;
import android.view.Window;
import android.view.WindowManager;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//全屏设置
requestWindowFeature(Window.FEATURE_NO_TITLE);
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
//将画布放进去
GameView gameView = new GameView(this);
setContentView(gameView);
}
}

import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
/**
* 小球实例
* @author ZHF
*
*/
public class Ball {
int x, y;  //小球的实时位置
int startX, startY;   //小球的初始位置
float vX, vY;    //小球的速度
int r; //小球的半径

double startTimeX;  //开始时间
double startTimeY;  //开始时间

BallThread ballThread;  //小球移动线程
Paint paint = new Paint();  //画笔

public Ball(int x, int y, float vX, float vY, int r) {
this.x = x;
this.y = y;
this.startX = x;
this.startY = y;
this.vX = vX;
this.vY = vY;
this.r = r;

//为每个小球实例化一个独立的线程，在抬手时开启线程
ballThread = new BallThread(this);

paint.setColor(Color.RED);  //小球为红色实心
}

/**绘画方法**/
public void drawSelf(Canvas canvas) {
canvas.drawCircle(x, y, r, paint);
}
}

import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
/**
* 障碍物
*
* @author ZHF
*
*/
public class Obstruction {
int x, y;
int hWeight;  //宽度和高度一样
Paint paint = new Paint();

public Obstruction(int x, int y, int hWeight) {
this.x = x;
this.y = y;
this.hWeight = hWeight;

paint.setColor(Color.GREEN);  //设置画笔颜色

}
public void drawSelf(Canvas canvas) {
canvas.drawRect(x - hWeight, y - hWeight, x + hWeight, y + hWeight, paint);
}
}

/**
* 小球移动和碰撞检测线程
* @author ZHF
*
*/
public class BallThread extends Thread {
boolean flag;   //标记线程是否开启
Ball ball;  //小球
double currentTime;  //当前时间

public BallThread(Ball ball) {
flag = true;
this.ball = ball;
}

@Override
public void run() {
while(flag) {
//调试：碰撞检测开始时间
long startTime = System.currentTimeMillis();

//计算出小球移动的时间片：将每次刷新分成若干时间小片段，用于计算每次时间小片段小球移动的距离
currentTime = System.nanoTime();
double timeSpanX = (currentTime - ball.startTimeX) /1000 /1000 /1000;
double timeSpanY = (currentTime - ball.startTimeY) /1000 /1000 /1000;

int xBackup = ball.x; //保存小球的碰撞前的位置
int yBackup = ball.y;
ball.x = (int) (ball.startX + ball.vX * timeSpanX);//小球移动的距离
ball.y = (int) (ball.startY + ball.vY * timeSpanY);

//边界碰撞检测
if((ball.vX > 0 && (ball.x + ball.r) >= 479) || (ball.vX < 0 && (ball.x - ball.r) <= 0)) {
ball.x = xBackup;
ball.vX = 0 - ball.vX;  //速度反向
ball.startTimeX = System.nanoTime();  //重新记录开始时间
ball.startX = ball.x;  //重新记录开始位置
}
if((ball.vY > 0 && (ball.y + ball.r) >= 799) || (ball.vY < 0 && (ball.y - ball.r) <= 0)) {
ball.y = yBackup;
ball.vY = 0 - ball.vY;   //速度反向
ball.startTimeY = System.nanoTime();   //重新记录开始时间
ball.startY = ball.y;   //重新记录开始位置
}

//障碍物碰撞检测
for(int i = 0; i < GameView.obstructList.size(); i++) {
Obstruction o = GameView.obstructList.get(i);
if(Math.abs(ball.x - o.x) < (ball.r + o.hWeight) && Math.abs(ball.y - o.y) < (ball.r + o.hWeight)){
if(Math.abs(xBackup - o.x) >= (ball.r + o.hWeight)) {
ball.x = xBackup;
ball.vX =  0 - ball.vX;
ball.startTimeX = System.nanoTime();
ball.startX = ball.x;
}
if(Math.abs(yBackup - o.y) >= (ball.r + o.hWeight)) {
ball.y = yBackup;
ball.vY = 0 - ball.vY;
ball.startTimeY = System.nanoTime();
ball.startY = ball.y;
}
break; //跳出循环
}
}

//调试：碰撞检测结束时间     实验证明碰撞加测基本不耗时间
long endTime = System.currentTimeMillis();
System.out.println(endTime + "----" + startTime + "= " +(endTime - startTime));

try {
Thread.sleep(10);
} catch (Exception e) {
e.printStackTrace();
}
}
}
}

import android.graphics.Canvas;
import android.util.Log;
import android.view.SurfaceHolder;
/**
* 绘画主界面线程
* @author ZHF
*
*/
public class DrawThread extends Thread {

boolean flag;  //标记线程是否开启
GameView gameView;
SurfaceHolder holder;
Canvas canvas;

public DrawThread(GameView gameView) {
flag = true;
this.gameView = gameView;
holder = gameView.getHolder();  //获取画布锁
}
@Override
public void run() {
while(flag) {
//获取当前绘画开始时间
long startTime = System.currentTimeMillis();
synchronized(holder) {
canvas = holder.lockCanvas(); //获取当前被锁住的画布
if(canvas != null) {
gameView.draw(canvas); //对画布进行操作
holder.unlockCanvasAndPost(canvas); //释放画布
}
}
long endTime = System.currentTimeMillis();
int diffTime = (int) (endTime - startTime);
Log.d("DrawTime", diffTime+"");

while(diffTime <= 2) {
diffTime = (int) (System.currentTimeMillis() - startTime);
Thread.yield(); //将线程的所有权交给另一个线程
}
}
}
}

import java.util.ArrayList;
import java.util.Random;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
/**
* 游戏主界面
* @author ZHF
*
*/
public class GameView extends SurfaceView implements SurfaceHolder.Callback {
SurfaceHolder holder;
DrawThread drawThread;  //绘画线程

Ball[] ballArray = new Ball[5];  //装小球的数组
int ballPointer = 0;  //当前指向数组中第几个球

static ArrayList<Obstruction> obstructList = new ArrayList<Obstruction>();   //装障碍物的集合

int xDown, yDown;  //记录手指按下时的坐标

public GameView(Context context) {
super(context);
holder = getHolder();  //获取画布锁
holder.addCallback(this);  //添加回调

//初始化障碍物
Random random = new Random();
for(int i = 0; i < 3; i++) {
Obstruction o = new Obstruction(random.nextInt(380) + 50, random.nextInt(700) + 50, 50);
obstructList.add(o); //将创出的障碍物对象添加到集合中去
}
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
drawThread = new DrawThread(this);
drawThread.start();    //开启绘画线程
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
//画布发生变化，eg:转屏操作,处理画布操作
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
//销毁画布操作
drawThread.flag = false;  //停掉线程
drawThread = null; //GC会及时发现并处理掉该对象
}
public void draw(Canvas canvas) {
canvas.drawColor(Color.BLACK);  //背景颜色
Paint paint = new Paint();
paint.setTextSize(25);
paint.setColor(Color.WHITE);  //文字颜色
canvas.drawText("小球碰撞检测", 50, 20, paint);

//画出小球
for(int i = 0; i < 5; i++) {
if(ballArray[i] != null) {
ballArray[i].drawSelf(canvas);  //当前小球绘画出自己
}
}
//画出障碍物
for(int i = 0; i < obstructList.size(); i++) {
obstructList.get(i).drawSelf(canvas);
}
}

@Override
public boolean onTouchEvent(MotionEvent event) {
int x = (int) event.getX();
int y = (int) event.getY();

if(event.getAction() == 0) {  //按下
//记录按下时X，Y的坐标
xDown = x;
yDown = y;
//生成第一个球
Ball ball = new Ball(x, y, 0, 0, 20);
if(ballArray[ballPointer] != null) {
ballArray[ballPointer].ballThread.flag = false;  //关闭小球移动线程
ballArray[ballPointer].ballThread = null;
}
ballArray[ballPointer] = ball;

} else if(event.getAction() == 1) { //抬起
int xOffset = x - xDown;
int yOffset = y - yDown;
double sin = yOffset / Math.sqrt(xOffset * xOffset + yOffset * yOffset);
double cos = xOffset / Math.sqrt(xOffset * xOffset + yOffset * yOffset);

ballArray[ballPointer].startTimeX = System.nanoTime(); //当前小球开始时间
ballArray[ballPointer].startTimeY = System.nanoTime();
ballArray[ballPointer].vX = (float) (500 * cos);  //当前小球的速度
ballArray[ballPointer].vY = (float) (500 * sin);
ballArray[ballPointer].ballThread.start();   //开启小球移动线程

ballPointer ++;  //下一个小球
if(ballPointer >= 5) {
ballPointer = 0;
}
}
return true;
}
}