android学习中--弹球游戏

package com.example.admin.imgapp;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.view.Display;
import android.view.KeyEvent;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;

import java.util.Random;
import java.util.Timer;
import java.util.TimerTask;

public class MainActivity extends AppCompatActivity {
Random random = new Random();

float bx = 100,by = 100;   //球的坐标
float b_size = 10;
double xyRate = random.nextDouble()-0.5;
int yspeed = 15;
int xspeed = (int)(yspeed*xyRate*2);

int rx= random.nextInt(200);//球拍的坐标
int ry =0;
float r_width = 90;
float r_height = 10;

boolean isOver = false;
int tableWidth,tableHeight;

@Override
protected void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);  //不要标题
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);//全屏
final GameView gameView = new GameView(this);
setContentView(gameView);  //设置页面为游戏界面

WindowManager wm = getWindowManager();
Display display = wm.getDefaultDisplay();
DisplayMetrics dm = new DisplayMetrics();
display.getMetrics(dm);
tableHeight = dm.widthPixels;
tableWidth = dm.widthPixels;
ry = tableHeight-20;

gameView.setOnKeyListener(new View.OnKeyListener() {
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
switch(event.getKeyCode()){
case KeyEvent.KEYCODE_A:
if(rx>0)rx-=10;break;
case KeyEvent.KEYCODE_D:
if(rx<tableWidth-r_width) rx+=10;break;
}
gameView.invalidate();
return true;
}
});

final Handler handler = new Handler(){
public void handleMessage(Message message){
if(message.what == 100){
gameView.invalidate(); //重绘
}
}
};

//定时器
final Timer timer = new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
//如果小球碰到左边的边框
if(bx<=0 || bx>=tableWidth-b_size){
xspeed = -xspeed;
}
//如果没接住
if(by>=ry-b_size &&(bx<rx || bx>rx+r_width)){
timer.cancel();
isOver = true;
} //接住了，反弹
else if(by<=0 ||(by>=ry-b_size && bx>rx && bx<=rx+r_width)){
yspeed = -yspeed;
}

by+=yspeed;
bx += xspeed;
handler.sendEmptyMessage(100);
}
},0,200);
}

/**
*游戏类
*/
class GameView extends View {
Paint paint = new Paint();
public GameView(Context context){
super(context);
setFocusable(true); //可获得焦点
}
public void onDraw(Canvas canvas){
paint.setStyle(Paint.Style.FILL);
paint.setAntiAlias(true);

if(isOver){
paint.setColor(Color.RED);
paint.setTextSize(40);
canvas.drawText("游戏结束",tableWidth/2-100,200,paint);
}else{
paint.setColor(Color.rgb(255,0,0));
canvas.drawCircle(bx,by,b_size,paint);
paint.setColor(Color.rgb(80,80,200));
canvas.drawRect(rx,ry,rx+r_width,ry+r_height,paint);
}

}
}
}